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1
Nelson, David A., e Todd W. Fortune. "High-Level Psychophysical Tuning Curves". Journal of Speech, Language, and Hearing Research 34, n. 2 (aprile 1991): 360–73. http://dx.doi.org/10.1044/jshr.3402.360.
Testo completoAbstract (sommario):
Simultaneous-masked psychophysical tuning curves were obtained from normal-hearing listeners using low-level (20–25 dB SPL) probe tones in quiet and high-level (60 dB SPL) probe tones, both in quiet and in the presence of a broad-band background noise. The background noise was introduced to eliminate combination tones or combination bands and other off-frequency listening cues that exist at high levels. Tuning curves were obtained using pure-tone maskers and 100-Hz-wide narrow-band noise maskers for probe tones at 1000 and 4000 Hz. High-level tuning curves for pure-tone maskers demonstrated large discontinuities or “notches” on the low-frequency sides of the tuning curves. Broad-band background noise eliminated those notches, indicating that the notches were due to the detection of off-frequency listening cues at combination-tone frequencies. High-level tuning curves for 100-Hz-wide narrow-band maskers also demonstrated notches on the low-frequency sides. Those notches were eliminated with broad-band background noise, which indicates that combination bands strongly influenced the shapes of high-level tuning curves obtained with narrow-band maskers. The influence of combination bands was dependent upon test frequency. At 1000 Hz, combination bands had very little influence on the shapes of high-level tuning curves. At 4000 Hz, where the masker bandwidth was substantially less than the critical bandwidth, combination bands strongly affected the low-frequency sides of the tuning curves. In 2 subjects tested at a probe frequency of 2000 Hz with 100-Hz-wide masking bands, combination bands also influenced the lowfrequency sides of high-level tuning curves. The presence of combination-tone or combination-band cues essentially steepened the low-frequency slopes of tuning curves, resulting in sharper estimates of tuning. Comparisons of tuning curves obtained with pure-tone maskers and narrow-band maskers, in the same listeners, revealed that pure-tone maskers were more effective than narrow-band maskers when the masker frequencies were in the tail region of the tuning curve. The results of these experiments support the notion that tuning in the normal auditory system broadens notably with stimulus level, once off-frequency listening cues such as combination tones or combination bands are eliminated. The low-level simultaneously masked tuning curve demonstrates a sharp bandpass tuning characteristic, whereas the high-level simultaneously masked tuning curve in background noise demonstrates a broad low-pass tuning characteristic. It is argued that comparisons of tuning in impaired ears with tuning in normal ears should be made using estimates of tuning in normal ears that are not influenced by combination-tone or combination-band detection cues.
2
Kordus, Monika, e Borys Kowalewski. "Effects of Low- and High-Frequency Side Bands of Notched Noise on Masking and Auditory Filter Shape at Very High Frequencies". Archives of Acoustics 40, n. 3 (1 settembre 2015): 329–36. http://dx.doi.org/10.1515/aoa-2015-0036.
Testo completoAbstract (sommario):
Abstract This paper is concerned with the determination of the auditory filter shape using the notched noise method with noise bands symmetrically located above and below a probe frequency of 10 kHz. Unlike in the classical experiments conducted with the use of Patterson method the levels as well as power spectrum densities of the lower and upper component bands of the notched noise masker were not the same and were set such as to produce the same amount of masking at the 10-kHz frequency. The experiment consisted of three conditions in which the following values were determined: (I) the detection threshold for a 10-kHz probe tone in the presence of a noise masker presented below the tone’s frequency; (II) the level of a noise masker presented above the 10-kHz probe tone frequency, at which the masker just masked the probe tone, (III) the detection threshold for a probe tone in the presence of a notched-noise masker. The data show a considerable amount of variability across the subjects, however, the resulting frequency characteristics of the auditory filters are consistent with those presented in the literature so that the Equivalent Rectangular Bandwidth is less than 11% of their centre frequency.
3
Sprague, Barbara H., Terry L. Wiley e Robert Goldstein. "Tympanometric and Acoustic-Reflex Studies in Neonates". Journal of Speech, Language, and Hearing Research 28, n. 2 (giugno 1985): 265–72. http://dx.doi.org/10.1044/jshr.2802.265.
Testo completoAbstract (sommario):
Tympanograms and acoustic reflexes for a broadband noise and for a 1000-Hz tone were measured in normal neonates. Notched tympanograms were typical of neonatal ears for a 220-Hz probe tone. A single-peaked tympanogram was most characteristic for a probe frequency of 660 Hz. Ipsilateral and contralateral acoustic reflexes were present more frequently for a 660-Hz probe tone compared to a 220-Hz probe tone, but acoustic-reflex thresholds were not significantly different between probe tones. As with adults, acoustic-reflex thresholds for the noise were significantly lower than for the tone, and ipsilateral reflex thresholds were lower than contralateral reflex thresholds. Reliability of acoustic-reflex and tympanometric measures was high. Age change from 2 to 4 days had no significant effect on tympanometric or acoustic-reflex characteristics. There was no apparent relation between tympanometric pattern and acoustic-reflex characteristics.
4
Ying-ying, Shang, Ni Dao-feng e Liu Shi-lin. "High- and Low-Frequency Probe Tone Tympanometry in Chinese Infants". Journal of Otology 2, n. 1 (giugno 2007): 42–51. http://dx.doi.org/10.1016/s1672-2930(07)50008-5.
Testo completo
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Lutolf, John J., Honor O'Malley e Shlomo Silman. "The Effects of Probe-Tone Frequency on the Acoustic-Reflex Growth Function". Journal of the American Academy of Audiology 14, n. 02 (febbraio 2003): 109–18. http://dx.doi.org/10.3766/jaaa.14.2.6.
Testo completoAbstract (sommario):
Acoustic-reflex growth functions (ARGFs) were obtained from 20 normal-hearing listeners, Contralateral acoustic reflexes (ARs) were elicited with pure tones of 2000 Hz. The magnitude of changes in static compliant susceptance (BA) and conductance (GA) were monitored with probe-tone frequencies of 226 Hz, 678 Hz and 1000 Hz. ARGFs were obtained with six combinations of probe-tone frequency/admittance component: 226 Hz BA, 226 Hz GA, 678 Hz BA, 678 Hz GA, 1000 Hz BA, and 1000 Hz GA. Peak conductance (GA) and susceptance (BA) ARs were largest within the 678 Hz GA and 1000 Hz BAARGFs, respectively. Among high-frequency probe tones, the patterns of AR growth were larger and less variable for the 678 Hz GA ARGF and the 1000 Hz BA ARGF as determined by the magnitude of their linear (b1) and quadratic (b2) polynomial coefficients and the value of their squared correlation coefficients (R2).
6
Sinex, D. G., e D. C. Havey. "Neural mechanisms of tone-on-tone masking: patterns of discharge rate and discharge synchrony related to rates of spontaneous discharge in the chinchilla auditory nerve". Journal of Neurophysiology 56, n. 6 (1 dicembre 1986): 1763–80. http://dx.doi.org/10.1152/jn.1986.56.6.1763.
Testo completoAbstract (sommario):
Responses of chinchilla auditory nerve fibers to brief probe tones in the presence of a fixed tonal masker were obtained. The stimulus conditions were analogous to those that have been used in many psychophysical experiments. The relation between previously described response properties of auditory nerve fibers and features of psychophysical tone-on-tone masking was examined. In psychophysical studies, a fixed narrowband masker produces a characteristic pattern of masked thresholds, which becomes broad and asymmetrical at high masker levels. In the present experiment 1, a 5,000-Hz masker was presented at 30, 50, and 70 dB SPL. Masked thresholds based on the average rate of response to probe tones were estimated for single auditory nerve fibers. The lowest of these masked thresholds formed a pattern similar to the psychophysical masking pattern, becoming broader and more asymmetrical as the masker was increased to 70 dB SPL. The masked thresholds of fibers with low and medium rates of spontaneous discharge (SR) were as low as or lower than the masked thresholds of fibers with high SRs. In certain frequency regions, masked thresholds based on responses to cochlear distortion products were lower than the masked thresholds of any fiber responding to the probe tone; this result is also similar to previous psychophysical observations. In experiment 2, responses of chinchilla auditory nerve fibers to probe tones in the presence of a masker at 1,000 Hz and 50 dB SPL were studied. Probe tone thresholds in the presence of this masker have been measured psychophysically in chinchillas. Thus the relation between behavioral and neural masked thresholds in the same species could be examined. Masked thresholds were estimated from average discharge rate responses and also from discharge synchrony. Good quantitative agreement was observed between the probe tone levels at which changes in average discharge rate were observed and the chinchilla's behavioral masked thresholds. For fibers matched for characteristic frequency, the masked thresholds based on average discharge rate of high-SR fibers tended to be elevated compared with the thresholds of medium-SR fibers. Changes in discharge rate synchronized to the probe tone occurred at levels lower than the chinchilla's behavioral masked thresholds. If discharge synchrony can be used for detection, the code would appear to be based on the relative synchrony to the probe tone and to the masking tone. Low synchrony masked thresholds were obtained from fibers with all SRs.(ABSTRACT TRUNCATED AT 400 WORDS)
7
Abdala, Carolina, Ping Luo e Yeini Guardia. "Swept-Tone Stimulus-Frequency Otoacoustic Emissions in Human Newborns". Trends in Hearing 23 (gennaio 2019): 233121651988922. http://dx.doi.org/10.1177/2331216519889226.
Testo completoAbstract (sommario):
Several types of otoacoustic emissions have been characterized in newborns to study the maturational status of the cochlea at birth and to develop effective tests of hearing. The stimulus-frequency otoacoustic emission (SFOAE), a reflection-type emission elicited with a single low-level pure tone, is the least studied of these emissions and has not been comprehensively characterized in human newborns. The SFOAE has been linked to cochlear tuning and is sensitive to disruptions in cochlear gain (i.e., hearing loss) in adult subjects. In this study, we characterize SFOAEs evoked with rapidly sweeping tones in human neonates and consider the implications of our findings for human cochlear maturation. SFOAEs were measured in 29 term newborns within 72 hr of birth using swept tones presented at 2 oct/s across a four-octave frequency range (0.5–8 kHz); 20 normal-hearing young adults served as a control group. The prevalence of SFOAEs in newborns was as high as 90% (depending on how response “presence” was defined). Evidence of probe-tip leakage and abnormal ear-canal energy reflectance was observed in those ears with absent or unmeasurable SFOAEs. Results in the group of newborns with present stimulus-frequency emissions indicate that neonatal swept-tone SFOAEs are adult-like in morphology but have slightly higher amplitude compared with adults and longer SFOAE group delays. The origin of these nonadult-like features is probably mixed, including contributions from both conductive (ear canal and middle ear) and cochlear immaturities.
8
Kei, Joseph, Julie Allison-Levick, Jacqueline Dockray, Rachel Harrys, Christina Kirkegard, Janet Wong, Marion Maurer, Jayne Hegarty, June Young e David Tudehope. "High-Frequency (1000 Hz) Tympanometry in Normal Neonates". Journal of the American Academy of Audiology 14, n. 01 (gennaio 2003): 020–28. http://dx.doi.org/10.3766/jaaa.14.1.4.
Testo completoAbstract (sommario):
The characteristics of high frequency (1000 Hz) acoustic admittance results obtained from normal neonates were described in this study. Participants were 170 healthy neonates (96 boys and 74 girls) aged between 1 and 6 days (mean = 3.26 days, SD = 0.92). Transient evoked otoacoustic emissions (TEOAEs), and 226 Hz and 1000 Hz probe tone tympanograms were obtained from the participants using a Madsen Capella OAE/middle ear analyser. The results showed that of the 170 neonates, 34 were not successfully tested in both ears, 14 failed the TEOAE screen in one or both ears, and 122 (70 boys, 52 girls) passed the TEOAE screen in both ears and also maintained an acceptable probe seal during tympanometry. The 1000 Hz tympanometric data for the 122 neonates (244 ears) showed a single-peaked tympanogram in 225 ears (92.2 %), a flat-sloping tympanogram in 14 ears (5.7 %), a double-peaked tympanogram in 3 ears (1.2 %) and other unusual shapes in 2 ears (0.8 %). There was a significant ear effect, with right ears showing significantly higher mean peak compensated static admittance and tympanometric width, but lower mean acoustic admittance at +200 daPa and gradient than left ears. No significant gender effects or its interaction with ear were found. The normative tympanometric data derived from this cohort may serve as a guide for detecting middle ear dysfunction in neonates.
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Gupta, Dipti, e C. S. Vanaja. "Effect of age on acoustic reflex thresholds in neonates and infants with normal hearing". International Journal of Otorhinolaryngology and Head and Neck Surgery 7, n. 5 (23 aprile 2021): 746. http://dx.doi.org/10.18203/issn.2454-5929.ijohns20211421.
Testo completoAbstract (sommario):
<p><strong>Background:</strong> High frequency (1000 Hz) probe tone holds substantial promise for carrying out acoustic reflexes in neonates and infants. A limited number of studies indicates that acoustic reflex thresholds (ART) also change significantly with age as the newborn hearing system matures. However, there is a need for obtaining more data before using it in a clinical population. The aim was to investigate effect of age of infants on ARTs. Effect of activator signal was also explored. <strong></strong></p><p><strong>Methods:</strong> ARTs were monitored using a 1 kHz probe tone for the 500 Hz, 1 kHz, 2 kHz, and 4 kHz pure tone activators in neonates and infants in the age range of 6 to 8 weeks were analysed.</p><p><strong>Results</strong>: The mean ARTs for neonates were lower compared to infants. Results of repeated measure ANOVA showed that there was a statistically significant age effect. Also, ARTs for high frequency activator signals were significantly higher than the ARTs for low frequency signals.</p><p><strong>Conclusions:</strong> The acoustic reflexes can be elicited for 500, 1000, 2000, and 4000 Hz when monitored using a 1000 Hz probe tone. There is an effect of age and activator signal on the acoustic reflex threshold. The data obtained in the present study can serve as normative for 0-1-week neonates and 6-8-weeks infants.</p>
10
Fernandez-Prieto, Irune, Charles Spence, Ferran Pons e Jordi Navarra. "Does Language Influence the Vertical Representation of Auditory Pitch and Loudness?" i-Perception 8, n. 3 (giugno 2017): 204166951771618. http://dx.doi.org/10.1177/2041669517716183.
Testo completoAbstract (sommario):
Higher frequency and louder sounds are associated with higher positions whereas lower frequency and quieter sounds are associated with lower locations. In English, “high” and “low” are used to label pitch, loudness, and spatial verticality. By contrast, different words are preferentially used, in Catalan and Spanish, for pitch (high: “agut/agudo”; low: “greu/grave”) and for loudness/verticality (high: “alt/alto”; low: “baix/bajo”). Thus, English and Catalan/Spanish differ in the spatial connotations for pitch. To analyze the influence of language on these crossmodal associations, a task was conducted in which English and Spanish/Catalan speakers had to judge whether a tone was higher or lower (in pitch or loudness) than a reference tone. The response buttons were located at crossmodally congruent or incongruent positions with respect to the probe tone. Crossmodal correspondences were evidenced in both language groups. However, English speakers showed greater effects for pitch, suggesting an influence of linguistic background.
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Lilaonitkul, Watjana, e John J. Guinan. "Reflex Control of the Human Inner Ear: A Half-Octave Offset in Medial Efferent Feedback That Is Consistent With an Efferent Role in the Control of Masking". Journal of Neurophysiology 101, n. 3 (marzo 2009): 1394–406. http://dx.doi.org/10.1152/jn.90925.2008.
Testo completoAbstract (sommario):
The high sensitivity and frequency selectivity of the mammalian cochlea is due to amplification produced by outer hair cells (OHCs) and controlled by medial olivocochlear (MOC) efferents. Data from animals led to the view that MOC fibers provide frequency-specific inhibitory feedback; however, these studies did not measure intact MOC reflexes. To test whether MOC inhibition is primarily at the frequency that elicits the MOC activity, acoustically elicited MOC effects were quantified in humans by the change in otoacoustic emissions produced by 60-dB SPL tone and half-octave-band noise elicitors at different frequencies relative to a 40-dB SPL, 1-kHz probe tone. On average, all elicitors produced MOC effects that were skewed (elicitor frequencies -1 octave below the probe produced larger effects than those -1 octave above). The largest MOC effects were from elicitors below the probe frequency for contra- and bilateral elicitors but were from elicitors centered at the probe frequency for ipsilateral elicitors. Typically, ipsilateral elicitors produced larger effects than contralateral elicitors and bilateral elicitors produced effects near the ipsi+contra sum. Elicitors at levels down to 30-dB SPL produced similar patterns. Tuning curves (TCs) interpolated from these data were V-shaped with Q10s ∼2. These are sharper than MOC-fiber TCs found near 1 kHz in cats and guinea pigs. Because cochlear amplification is skewed (more below the best frequency of a cochlear region), these data are consistent with an anti-masking role of MOC efferents that reduces masking by reducing the cochlear amplification seen at 1 kHz.
12
Shahnaz, Navid, Terence Miranda e Linda Polka. "Multifrequency Tympanometry in Neonatal Intensive Care Unit and Well Babies". Journal of the American Academy of Audiology 19, n. 05 (maggio 2008): 392–418. http://dx.doi.org/10.3766/jaaa.19.5.3.
Testo completoAbstract (sommario):
Background: Conventional low probe tone frequency tympanometry has not been successful in identifying middle ear effusion in newborn infants due to differences in the physiological properties of the middle ear in newborn infants and adults. With a rapid increase in newborn hearing screening programs, there is a need for a reliable test of middle ear function for the infant population. In recent years, new evidence has shown that tympanometry performed at higher probe tone frequencies may be more sensitive to middle ear disease than conventional low probe tone frequency in newborn infants. Purpose: The main goal of this study was to explore the characteristics of the normal middle ear in the NICU (neonatal intensive care unit) and well babies using conventional and multifrequency tympanometry (MFT). It was also within the scope of this study to compare conventional and MFT patterns in NICU and well babies to already established patterns in adults to identify ways to improve hearing assessment in newborns and young infants. Methods: Three experiments were conducted using standard and MFT involving healthy babies and NICU babies. NICU babies (n = 33), healthy three-week-old babies (n = 16), and neonates on high-priority hearing registry (HPHR) (n = 42) were tested. Thirty-two ears of 16 healthy Caucasian adults (compared to well-babies) and 47 ears of 26 healthy Caucasian adults (compared to NICU babies) were also included in this study. Results: The distribution of the Vanhuyse patterns as well as variation of admittance phase and peak compensated susceptance and conductance at different probe tone frequencies was also explored. In general, in both well babies and NICU babies, 226 Hz tympanograms are typically multipeaked in ears that passed or referred on transient otoacoustic emission (TEOAE), limiting the specificity and sensitivity of this measure for differentiating normal and abnormal middle ear conditions. Tympanograms obtained at 1 kHz are potentially more sensitive and specific to presumably abnormal and normal middle ear conditions. Tympanometry at 1 kHz is also a good predictor of presence or absence of TEOAE.
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Norrix, Linda W., Briana Burgan, Nicholas Ramirez e David S. Velenovsky. "Interaural Multiple Frequency Tympanometry Measures: Clinical Utility for Unilateral Conductive Hearing Loss". Journal of the American Academy of Audiology 24, n. 03 (marzo 2013): 231–40. http://dx.doi.org/10.3766/jaaa.24.3.8.
Testo completoAbstract (sommario):
Background: Tympanometry is a routine clinical measurement of the acoustic immittance of the ear as a function of ear canal air pressure. The 226 Hz tympanogram can provide clinical evidence for conditions such as a tympanic membrane perforation, Eustachian tube dysfunction, middle ear fluid, and ossicular discontinuity. Multiple frequency tympanometry using a range of probe tone frequencies from low to high has been shown to be more sensitive than a single probe tone tympanogram in distinguishing between mass- and stiffness-related middle ear pathologies (Colletti, 1975; Funasaka et al, 1984; Van Camp et al, 1986). Purpose: In this study we obtained normative measures of middle ear resonance by using multiple probe tone frequency tympanometry. Ninety percent ranges for middle ear resonance and for interaural differences were calculated. Research Design: In a mixed design, normative data were collected from both ears of male and female adults. Study Sample: Twelve male and 12 female adults with normal hearing and normal middle ear function participated in the study. Data Collection and Analysis: Multiple frequency tympanograms were recorded with a commercially available immittance instrument (GSI Tympstar) to obtain estimates of middle ear resonant frequency (RF) using ΔB, positive tail, and negative tail methods. Data were analyzed using three-way mixed analyses of variance with gender as a between-subject variable and ear and method as within-subject variables. T-tests were performed, using the Bonferroni adjustment, to determine significant differences between means. Results: Using the positive and negative tail methods, a wide range of approximately 500 Hz was found for middle ear resonance in adults with normal hearing and normal middle ear function. The difference in RF between an individual's ears is small with 90% ranges of approximately ±200 Hz, indicating that the right ear RF should be either 200 Hz higher or lower in frequency compared to the left ear. This was true for both negative and positive tail methods. Conclusion: Ninety percent ranges were calculated to determine the difference in middle ear resonance expected between an individual's ears. These ranges can provide critical normative values for determining how pathology in an ear with a unilateral conductive hearing loss is altering the mass or stiffness characteristics of the middle ear system.
14
Souchal, Marion, Ludimila Labanca, Sirley Alves da Silva Carvalho, Luciana Macedo de Resende, Christelle Blavignac, Paul Avan e Fabrice Giraudet. "Transient Abnormalities in Masking Tuning Curve in Early Progressive Hearing Loss Mouse Model". BioMed Research International 2018 (2018): 1–12. http://dx.doi.org/10.1155/2018/6280969.
Testo completoAbstract (sommario):
Damage to cochlear outer hair cells (OHCs) usually affects frequency selectivity in proportion to hearing threshold increase. However, the current clinical heuristics that attributes poor hearing performance despite near-normal auditory sensitivity to auditory neuropathy or “hidden” synaptopathy overlooks possible underlying OHC impairment. Here, we document the part played by OHCs in influencing suprathreshold auditory performance in the presence of noise in a mouse model of progressive hair cell degeneration, the CD1 strain, at postnatal day 18–30 stages when high-frequency auditory thresholds remained near-normal. Nonetheless, total loss of high-frequency distortion product otoacoustic emissions pointed to nonfunctioning basal OHCs. This “discordant profile” came with a huge low-frequency shift of masking tuning curves that plot the level of interfering sound necessary to mask the response to a probe tone, against interfering frequency. Histology revealed intense OHC hair bundle abnormalities in the basal cochlea uncharacteristically associated with OHC survival and preserved coupling with the tectorial membrane. This pattern dismisses the superficial diagnosis of “hidden” neuropathy while underpinning a disorganization of cochlear frequency mapping with optimistic high-frequency auditory thresholds perhaps because responses to high frequencies are apically shifted. The audiometric advantage of frequency transposition is offset by enhanced masking by low-frequency sounds, a finding essential for guiding rehabilitation.
15
Nelson, David A. "High-Level Psychophysical Tuning Curves". Journal of Speech, Language, and Hearing Research 34, n. 6 (dicembre 1991): 1233–49. http://dx.doi.org/10.1044/jshr.3406.1233.
Testo completoAbstract (sommario):
Forward-masked psychophysical tuning curves (PTCs) were obtained for 1000-Hz probe tones at multiple probe levels from one ear of 26 normal-hearing listeners and from 24 ears of 21 hearing-impaired listeners with cochlear hearing loss. Comparisons between normal-hearing and hearing-impaired PTCs were made at equivalent masker levels near the tips of PTCs. Comparisons were also made of PTC characteristics obtained by fitting each PTC with three straight-line segments using least-squares fitting procedures. Abnormal frequency resolution was revealed only as abnormal downward spread of masking. The low-frequency slopes of PTCs from hearing-impaired listeners were not different from those of normal-hearing listeners. That is, hearing-impaired listeners did not demonstrate abnormal upward spread of masking when equivalent masker levels were compared. Ten hearing-impaired ears demonstrated abnormally broad PTCs, due exclusively to reduced high-frequency slopes in their PTCs. This abnormal downward spread of masking was observed only in listeners with hearing losses greater than 40 dB HL. From these results, it would appear that some, but not all, cochlear hearing losses greater than 40dB HL influence the sharp tuning capabilities usually associated with outer hair cell function.
16
Yerraguntla, Krishna, Ramanjeet Kaur e Rohit Ravi. "A Preliminary Attempt to Profile Tympanometric Measures in Infants Using High Frequency Probe Tones". Indian Journal of Otolaryngology and Head & Neck Surgery 70, n. 2 (21 giugno 2016): 188–93. http://dx.doi.org/10.1007/s12070-016-1004-2.
Testo completo
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Rubsamen, R., D. M. Mills e E. W. Rubel. "Effects of furosemide on distortion product otoacoustic emissions and on neuronal responses in the anteroventral cochlear nucleus". Journal of Neurophysiology 74, n. 4 (1 ottobre 1995): 1628–38. http://dx.doi.org/10.1152/jn.1995.74.4.1628.
Testo completoAbstract (sommario):
1. The objective of this study was to precisely evaluate the relationship between the threshold of neurons in the anteroventral cochlear nucleus (AVCN) and the properties of distortion product otoacoustic emissions (DPOAEs). Response areas of multiunit clusters in the AVCN and DPOAEs in the ear canal were measured alternately in the adult gerbil during furosemide-induced changes of the endocochlear potential. Stimulus frequencies of the probe tones for DPOAE measurement were in the range of f1 = 1.7-7.6 kHz and f2 = 2.0-9.0 kHz; the ratio f2:f1 was always 1.18. Stimulus amplitudes were varied in 5-dB steps from 30 to 80 dB SPL, with either equal amplitudes (L1 = L2) or unequal, with L1 set 10 dB above L2. Multiunit response areas were determined from cluster responses to a series of 100-ms tone bursts presented with a pseudo-random sequence in frequency and intensity. 2. Changes in the multiunit discharge properties after 50-75 mg/kg furosemide injection were as follows: the best frequency (BF) threshold increased from initial values in the range of 20-30 dB SPL to 50-80 dB SPL at 10-20 min postinjection and then recovered fully by 60-90 min. The spontaneous discharge activity decreased to zero before any changes in the frequency threshold curve were observed and did not return to initial values for several hours. Likewise, total discharge rates of stimulus elicited responses were reduced and tended to stay reduced even after BF threshold had fully recovered. 3. From the DPOAE measurements, the changes observed in the cubic distortion tone (CDT, 2f1-f2) emission after furosemide injection were as follows: at high levels of the probe tones, changes in the emission intensities generally stayed within a 10-dB range. The CDT amplitudes for low stimulus levels, however, were typically reduced by up to 40 dB, but recovered (depending on the furosemide dosage) by approximately 60-90 min. 4. At low to moderate stimulus levels of 40-60 dB SPL, there was a near perfect, minute-by-minute covariation of the ear canal CDT amplitude and the BF threshold measured in the AVCN. A 10-dB increase in threshold was associated with a 5- to 7-dB decrease in the CDT emission. 5. The optimum stimulus parameter set for the noninvasive estimation of cochlear performance from the CDT response was for stimulus amplitudes L1 = 50, L2 = 40 dB SPL. 6. This experiment demonstrates that CDT emissions at low stimulus levels are very good predictors of the thresholds of cochlear afferents, but this validity is lost for BF thresholds greater than approximately 60-70 dB SPL. 7. The ear canal CDT amplitude is better correlated with the BF threshold sensitivity of neuronal response areas in the AVCN than with the spontaneous discharge rate or absolute above-threshold discharge rates.
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Nelson, David A., e Todd W. Fortune. "High-Level Psychophysical Tuning Curves". Journal of Speech, Language, and Hearing Research 34, n. 2 (aprile 1991): 374–78. http://dx.doi.org/10.1044/jshr.3402.374.
Testo completoAbstract (sommario):
Simultaneous-masked psychophysical tuning curves were measured with narrow-band noise maskers varying in bandwidth from 40 Hz to 800 Hz to determine the masker bandwidths at which combination-band detection cues no longer influence tuning-curve shapes. Tuning curves were obtained at 1000 and 4000 Hz from normal-hearing listeners using high-level (60 dB SPL) probe tones in quiet and in the presence of a broadband background noise to eliminate combination bands and other off-frequency listening cues that exist at high levels. High-level tuning curves revealed notches on the low-frequency sides. Those notches were eliminated with broad-band background noise, which indicates that combination bands can strongly influence the shapes of high-level tuning curves obtained with narrow-band maskers, primarily by steepening the low-frequency and tail slopes. Combination-band detection cues had a stronger influence at 4000 Hz than at 1000 Hz. As masker bandwidth increased, combination bands had less influence on tuning-curve shapes. These results suggest a possible relation between masker bandwidth and auditory critical bandwidth: combination bands affected the lowfrequency sides of the tuning curves only when the masker bandwidth was less than the auditory critical bandwidth.
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Arregui, Guillermo, Martín F. Colombano, Jeremie Maire, Alessandro Pitanti, Néstor E. Capuj, Amadeu Griol, Alejandro Martínez, Clivia M. Sotomayor-Torres e Daniel Navarro-Urrios. "Injection locking in an optomechanical coherent phonon source". Nanophotonics 10, n. 4 (1 gennaio 2021): 1319–27. http://dx.doi.org/10.1515/nanoph-2020-0592.
Testo completoAbstract (sommario):
Abstract Spontaneous locking of the phase of a coherent phonon source to an external reference is demonstrated in a deeply sideband-unresolved optomechanical system. The high-amplitude mechanical oscillations are driven by the anharmonic modulation of the radiation pressure force that result from an absorption-mediated free-carrier/temperature limit cycle, i.e., self-pulsing. Synchronization is observed when the pump laser driving the mechanical oscillator to a self-sustained state is modulated by a radiofrequency tone. We employ a pump-probe phonon detection scheme based on an independent optical cavity to observe only the mechanical oscillator dynamics. The lock range of the oscillation frequency, i.e., the Arnold tongue, is experimentally determined over a range of external reference strengths, evidencing the possibility to tune the oscillator frequency for a range up to 350 kHz. The stability of the coherent phonon source is evaluated via its phase noise, with a maximum achieved suppression of 44 dBc/Hz at 1 kHz offset for a 100 MHz mechanical resonator. Introducing a weak modulation in the excitation laser reveals as a further knob to trigger, control and stabilize the dynamical solutions of self-pulsing based optomechanical oscillators, thus enhancing their potential as acoustic wave sources in a single-layer silicon platform.
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Janssen, B. J., S. C. Malpas, S. L. Burke e G. A. Head. "Frequency-dependent modulation of renal blood flow by renal nerve activity in conscious rabbits". American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 273, n. 2 (1 agosto 1997): R597—R608. http://dx.doi.org/10.1152/ajpregu.1997.273.2.r597.
Testo completoAbstract (sommario):
To examine the influence of the various frequency components of renal sympathetic nerve activity (RSNA) on renal blood flow (RBF) dynamics, a Doppler flow probe and renal nerve electrode were implanted on the left renal artery of 10 rabbits. Experiments were performed 4-9 days after surgery. Physiological changes in RSNA were induced by subjecting the rabbits to periods of breathing hypoxic gas mixtures. Signals were sampled at 1 kHz and analyzed by spectral analysis. During moderate hypoxia (arterial PO2 = 44 +/- 1 mmHg), arterial pressure and heart rate did not change, averaged RSNA increased by 90 +/- 7%, and RBF fell by 18 +/- 3%. In a separate group of renal-denervated rabbits (n = 6), no changes in RBF occurred during hypoxia. In intact rabbits, 53 +/- 4% of spectral density power of RSNA was found at the cardiac frequency and the remainder was predominantly coupled to respiration (approximately 0.9 Hz). During moderate hypoxia the amplitude of the RSNA oscillations increased 17 +/- 6 times at the cardiac frequency and 10 +/- 3 times at the respiration-related frequency. Modulation of RBF variability by the fluctuations of RSNA at the cardiac- and respiration-related frequency was, however, small. The normalized transfer gain between RSNA and RBF was approximately 0.1 at > 0.5 Hz. This means that, at > 0.5 Hz, maximally 10% of the amplitude of the RSNA oscillations is transmitted to corresponding RBF fluctuations. These transfer properties did not change during hypoxia. At < 0.5 Hz the transfer gain between RSNA and RBF increased. During moderate hypoxia, 0.3-Hz coherent oscillations of RSNA and RBF were found. In renal-denervated rabbits, 0.3-Hz oscillations in RBF were absent. Thus the renal vasculature was able to follow relatively low-frequency (< 0.5-Hz) fluctuations of RSNA and responded with corresponding oscillations in RBF. In contrast, the renal vasculature responded with increased constriction at the high-frequency (> 0.5-Hz) fluctuations of RSNA. These findings suggest that, in conscious rabbits, high-frequency oscillations of RSNA contribute to the vasoconstrictor tone, whereas the lower frequencies of RSNA contribute to the variability of RBF.
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Aithal, Venkatesh, Joseph Kei, Carlie Driscoll, Andrew Swanston, Katrina Roberts, Michio Murakoshi e Hiroshi Wada. "Normative Sweep Frequency Impedance Measures in Healthy Neonates". Journal of the American Academy of Audiology 25, n. 04 (aprile 2014): 343–54. http://dx.doi.org/10.3766/jaaa.25.4.6.
Testo completoAbstract (sommario):
Background: Diagnosing middle ear disorders in neonates is a challenging task for both audiologists and otolaryngologists. Although high-frequency (1000 Hz) tympanometry and acoustic stapedial reflex tests are useful in diagnosing middle ear problems in this age group, they do not provide information about the dynamics of the middle ear in terms of its resonance frequency (RF) and mobility. The sweep frequency impedance (SFI) test can provide this information, which may assist in the diagnosis of middle ear dysfunction in neonates. Purpose: This study aimed to investigate the feasibility of testing neonates using the SFI technique, establish normative SFI data for RF and mobility of the middle ear in terms of changes in sound pressure level (ΔSPL in dB), and describe the dynamics of the middle ear in healthy Australian neonates. Study Sample: A prospective sample of 100 neonates (58 males, 42 females) with a mean gestational age of 39.3 wk (SD = 1.3 wk; range = 38–42 wk), who passed all three tests, namely, automated auditory brainstem response, transient evoked otoacoustic emissions, and 1000 Hz tympanometry, were included in this study. Data Collection and Analysis: A SFI research prototype was used to collect the data. First, the SPL in the ear canal was measured as a probe-tone frequency was swept from 100–2000 Hz with the ear canal static pressure held constant at 200 daPa. Then, this measurement was repeated with the static pressure reduced in 50 daPa steps to –200 daPa. Additional measurement was also performed at the static pressure, where the peak of the 1000 Hz tympanogram occurred. A graph showing the variation of SPL against frequency at all static pressures was plotted. From this graph, the RF and ΔSPL at tympanometric peak pressure (TPP) were determined. Descriptive statistics and an analysis of variance (ANOVA) were applied to the RF and ΔSPL data with gender and ear as independent variables. Results: The results showed two resonance regions of the outer/middle ear with the high RF (mean = 1236 Hz; 90% range: 830–1518 Hz) being approximately equal to four times that of the low RF (mean = 287 Hz; 90% range = 209–420 Hz). The low RF was more easily identifiable than the high RF. The ΔSPL at the low RF (mean = 8.2 dB; 90% range = 3.4–13 dB) was greater than that at the high RF (mean = 5.0 dB; 90% range = 1.5–8.1 dB). There were no significant differences or interactions between genders and ears. Conclusion: The study showed that the SFI is a feasible test of middle ear function in neonates. The SFI results revealed two regions of resonance with the lower resonance (287 Hz) possibly related to the movements of the outer ear canal wall and higher resonance (1236 Hz) related to the resonance of the middle ear. The normative data developed in this study will be useful in evaluating outer and middle ear function in neonates.
22
Keppler, Hannah, Sofie Degeest e Bart Vinck. "Short-Term Test–Retest Reliability of Contralateral Suppression of Click-Evoked Otoacoustic Emissions in Normal-Hearing Subjects". Journal of Speech, Language, and Hearing Research 64, n. 3 (17 marzo 2021): 1062–72. http://dx.doi.org/10.1044/2020_jslhr-20-00393.
Testo completoAbstract (sommario):
Purpose The objective of the current study was to investigate the short-term test–retest reliability of contralateral suppression (CS) of click-evoked otoacoustic emissions (CEOAEs) using commercially available otoacoustic emission equipment. Method Twenty-three young normal-hearing subjects were tested. An otoscopic evaluation, admittance measures, pure-tone audiometry, measurements of CEOAEs without and with contralateral acoustic stimulation (CAS) to determine CS were performed at baseline ( n = 23), an immediate retest without and with refitting of the probe (only CS of CEOAEs; n = 11), and a retest after 1 week ( n = 23) were performed. Test–retest reliability parameters were determined on CEOAE response amplitudes without and with CAS, and on raw and normalized CS indices between baseline and the other test moments. Results Repeated-measures analysis of variance indicated no random or systematic changes in CEOAE response amplitudes without and with CAS, and in raw and normalized CS indices between the test moments. Moderate-to-high intraclass correlation coefficients with mostly high significant between-subjects variability between baseline and each consecutive test moment were found for CEOAE response amplitude without and with CAS, and for the raw and normalized CS indices. Other reliability parameters deteriorated between CEOAE response amplitudes with CAS as compared to without CAS, between baseline and retest with probe refitting, and after 1 week, as well as for frequency-specific raw and normalized CS indices as compared to global CS indices. Conclusions There was considerable variability in raw and normalized CS indices as measured using CEOAEs with CAS using commercially available otoacoustic emission equipment. More research is needed to optimize the measurement of CS of CEOAEs and to reduce influencing factors, as well as to make generalization of test–retest reliability data possible.
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Guimond, J. G., M. R. Pinsky e G. M. Matuschak. "Effect of synchronous increase in intrathoracic pressure on cardiac performance during acute endotoxemia". Journal of Applied Physiology 69, n. 4 (1 ottobre 1990): 1502–8. http://dx.doi.org/10.1152/jappl.1990.69.4.1502.
Testo completoAbstract (sommario):
In the anesthetized closed-chest canine model of Gram-negative endotoxemia (n = 10), we tested the hypothesis that the effect of cardiac cycle-specific intrathoracic pressure pulses delivered by a heart rate-(HR) synchronized high-frequency jet ventilator (sync HFJV) on systolic ventricular performance is dependent on the level of preload. To control for HFJV frequency, hemodynamic responses were also measured at fixed frequency within 15% of HR (async HFJV). Biventricular stroke volumes (SV) were measured by electromagnetic flow probes. Measurements were made before (baseline) and 30 min after infusion of 1 mg/kg Escherichia coli endotoxin (serotype 055:B5) and then after 2 mg/kg propranolol at both low (less than 10 mmHg) left ventricular filling pressure (LVFP) and high (greater than 10 mmHg) LVFP. Ventricular function curves, aortic pressure-flow (P-Q) relationships, and venous return (VR) curves were analyzed. We found that endotoxin did not alter VR curves but shifted the aortic P-Q curves to the left with pressure on the x-axis (P less than 0.05). Volume loading increased SV (P less than 0.01) because of a rightward shift of the VR curve. No specific differences occurred with either sync or async HFJV during endotoxin, presumably because of preserved VR and shifted aortic P-Q. The lack of cardiac cycle-specific effects of ITP appears to be due to the selective endotoxin-induced changes in peripheral vasomotor tone that counterbalance any depressed myocardial contractility.
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Stauss, H. M., e K. C. Kregel. "Frequency response characteristic of sympathetic-mediated vasomotor waves in conscious rats". American Journal of Physiology-Heart and Circulatory Physiology 271, n. 4 (1 ottobre 1996): H1416—H1422. http://dx.doi.org/10.1152/ajpheart.1996.271.4.h1416.
Testo completoAbstract (sommario):
Power spectrum analysis of arterial blood pressure (BP) and heart rate (HR) has been used to investigate autonomic nervous system activity. Sympathetic-mediated vasomotor tone has been attributed to the BP power at frequencies between 0.05 and 0.15 Hz in humans and dogs and between 0.2 and 0.8 Hz in rats. In contrast, it has been suggested that the sympathetic nervous system is too sluggish to transmit frequencies higher than 0.017 Hz in dogs. Thus we investigated the frequency-response characteristics of the transmission of peripheral sympathetic nerve discharge to peripheral vascular resistance and arterial blood pressure in conscious rats. Eleven rats were instrumented with arterial catheters, nerve electrodes on the sympathetic splanchnic nerve, and flow probes on the superior mesenteric artery. The splanchnic nerve was cut proximal to the electrode to avoid afferent nerve stimulation. The next day the nerve was stimulated at frequencies of 0.05, 0.1, 0.2, 0.5, 1.0, and 2.0 Hz while mesenteric blood flow, BP, and HR were recorded in conscious rats. Mesenteric resistance (MR) was calculated off-line. Nerve stimulation at 0.05, 0.1, 0.2, 0.5, and 1.0 Hz significantly increased the power in MR at these respective frequencies. The greatest response was found between 0.2 and 0.5 Hz. These oscillations in MR were translated to oscillations in BP, but not in HR. Nerve stimulation on the second day, when the nerve was degenerated, did not elicit oscillations in MR or BP. We conclude that the peripheral sympathetic nervous system in rats can transmit signals at frequencies higher than those traditionally assigned to sympathetic vasomotor activity in several species, including humans, and may even overlap with the respiration-related high-frequency range.
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Zinkovska, S. M., E. K. Rodriguez e D. A. Kirby. "Coronary and total peripheral resistance changes during sleep in a porcine model". American Journal of Physiology-Heart and Circulatory Physiology 270, n. 2 (1 febbraio 1996): H723—H729. http://dx.doi.org/10.1152/ajpheart.1996.270.2.h723.
Testo completoAbstract (sommario):
Changes in autonomic tone in the vasculature during sleep may have important implications for silent ischemia and sudden cardiac death. Few models exist in which both cardiac output and coronary blood flow are continuously measured during natural sleep and autonomic mechanisms are assessed. Catheters were chronically implanted in the aorta to measure mean arterial pressure (MAP), and flow probes were placed on the ascending aorta and the circumflex coronary artery of 18 pigs. Electrodes determined sleep stage as either non-rapid eye movement (NREM) or rapid eye movement (REM) sleep. The MAP was 73 +/- 3 mmHg in the quiet awake state, did not change in NREM, and decreased to 64 +/- 2 mmHg in REM sleep (P < 0.05). In NREM sleep, heart rate did not change from awake state values of 136 +/- 8 beats/min but increased by 5 beats/min in REM sleep (P < 0.05). Coronary vascular resistance decreased from awake state values of 2.7 +/- 0.2 to 2.2 +/- 0.2 mmHg.ml-1.min in REM (P < 0.05); total peripheral resistance decreased from awake values of 0.061 +/- 0.004 mmHg.ml-1.min to 0.050 +/- 0.003 in REM sleep (P < 0.05). Those changes appear to have been mediated primarily by reduction of alpha-adrenergic activity. Spectral analysis of heart rate suggests that power in the high-frequency range (a presumed indicator of parasympathetic tone) was lower in REM sleep than NREM sleep.
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Kei, Joseph. "Acoustic Stapedial Reflexes in Healthy Neonates: Normative Data and Test-Retest Reliability". Journal of the American Academy of Audiology 23, n. 01 (gennaio 2012): 046–56. http://dx.doi.org/10.3766/jaaa.23.1.5.
Testo completoAbstract (sommario):
Background: The acoustic stapedial reflex (ASR) test provides useful information about the function of the auditory system. While it is frequently used with adults and children in a clinical setting, its use with young infants is limited. Presently, there are few data for neonates and inadequate research into the test-retest reliability of the ASR test. Purpose: This study aimed to establish normative data and evaluate the test-retest reliability of the ASR test in healthy neonates. Research Design: A cross-sectional experimental design was used to establish ASR normative data and assess the test-retest reliability of ASR thresholds obtained from healthy neonates. Study Sample: Sixty-eight full-term neonates with mean chronological age of 2.5 days (SD = 1.8 day), who passed the automated auditory brainstem response, transient evoked otoacoustic emission, and high frequency (1 kHz) tympanometry (HFT) tests. Data Collection and Analysis: One randomly selected ear from each neonate was tested using TEOAE (transient evoked otoacoustic emission), HFT, and ASR tests using a 1 kHz probe tone. ASR thresholds were elicited by presenting pure tones of 0.5, 2, and 4 kHz and broadband noise (BBN) separately to the test ear in an ipsilateral stimulation mode. The ASR procedure was repeated to acquire retest data within the same testing session. Descriptive statistics, χ2, and analysis of variance with repeated measures tests were used to analyze ASR data. Results: All neonates exhibited ASR when stimulated by tonal stimuli or BBN. The mean ASRTs (acoustic stapedial reflex thresholds) for the 0.5, 2, and 4 kHz tones were 81.6 ± 7.9, 71.3 ± 7.9, and 65.4 ± 8.7 dB HL, respectively. The mean ASRT for the BBN was estimated to be smaller than 57.2 dB HL, given the limitation of the equipment. The 95th percentiles of the ASRT were 95, 85, 80, and 75 dB HL for the 0.5, 2, and 4 kHz and BBN, respectively. The test-retest reliability of the ASR test for all stimuli was high, with no significant difference in mean ASRTs across the test and retest conditions. Test-retest differences were within 10 dB for more than 91% of ASRT data across all stimuli. There was a slight trend of ASRTs being more repeatable in the medium ASRT range than in the higher or lower range. Conclusions: This study demonstrated that ASRTs obtained from healthy neonates were highly repeatable across test and retest sessions. Given the availability of normative data and the high test-retest reliability, the ASR test will be useful as a diagnostic tool in a battery of tests to evaluate the auditory function of neonates.
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Carpenter, MiChelle S., Anthony T. Cacace e Marty J. Mahoney. "Missing Links in Some Curious Auditory Phenomena: A Tale from the Middle Ear". Journal of the American Academy of Audiology 23, n. 02 (febbraio 2012): 106–14. http://dx.doi.org/10.3766/jaaa.23.2.5.
Testo completoAbstract (sommario):
Background: Broadband middle ear power reflectance (BMEPR) is an emerging noninvasive electroacoustic measure that evaluates transmission/reflection properties of the middle ear in high resolution. It is applicable over the entire age continuum and is rapid to perform. However, it remains to be determined if BMEPR is just an incremental step in the evolution of middle ear assessment or a major advance in the way middle ear function can be evaluated. Purpose: To evaluate effects of age, gender, ear, and frequency on BMEPR measurements in adults without a history of middle ear disease and to assess whether these factors require consideration in test development; to review how these data may influence active physiologic process within the inner ear; to consider how they reconcile with previously published results; and to suggest applications for future research. Research Design: Prospective, cross-sectional, multivariate analysis to evaluate the effects of age, gender, ear, and frequency on BMEPR in humans without a history of middle ear disease and no air-bone gaps exceeding 10 dB for any frequency. Study Sample: Fifty-six adults in two age groups (Group 1: 18–25 yr, n = 28; Group 2: ≥50 and <66 yr, n = 28). Each age group was stratified by ear and gender in a balanced design. Data Collection and Analysis: Pure tone air conduction and bone-conduction audiometry was conducted in a commercial sound booth, using a clinical audiometer with standard earphones enclosed in supra-aural ear cushions, and a standard bone-conduction oscillator and headband to evaluate for air-bone gaps. Broadband middle ear power reflectance was measured using a calibrated, commercially available computer-controlled system that incorporated a high quality probe assembly to transduce stimuli and record acoustic responses from the ear canal. Data were analyzed with a four-way (2 × 2 × 2 × 16) repeated measures analysis-of-variance (ANOVA) to evaluate the effects of age group (young vs. old), gender (male vs. female), ear (left vs. right), and frequency (258 to 5040 Hz) on BMEPR. Results: The ANOVA revealed a significant main effect of frequency. There were also gender × ear, gender × frequency, and age × gender × ear interactions. The three-way, age × gender × ear interaction captured the essence of results and revealed lowest power reflectance values in younger females and for right ears. This trend partially reversed in the older age group where higher power reflectance values were observed only in right ears of older females. Conclusions: The significant effects of age, gender, ear, and frequency on BMEPR parallel ear- and gender-related differences in hearing sensitivity, ear, and gender differences in the prevalence of spontaneous otoacoustic emissions (OAEs), gender differences in the magnitude of transient evoked OAEs, and ear differences in transient evoked contralateral OAE suppression effects reported in the literature. While original discussions of these aforementioned effects focused primarily on endocochlear and olivocochlear mechanisms, the BMEPR measurements reported herein suggest that middle ear transmission characteristics may also play a role.
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Shahnaz, Navid, e Linda Polka. "Distinguishing Healthy from Otosclerotic Ears: Effect of Probe-Tone Frequency on Static Immittance". Journal of the American Academy of Audiology 13, n. 07 (luglio 2002): 345–55. http://dx.doi.org/10.1055/s-0040-1715979.
Testo completoAbstract (sommario):
The diagnostic utility of static immittance (SI) with respect to distinguishing healthy from otosclerotic ears was investigated at different probe-tone frequencies in 68 healthy ears and 36 ears with surgically confirmed otosclerosis. Because one effect of otosclerosis is to shift the resonant frequency of the middle ear to higher values as a result of increased stiffness of the middle ear system, it was hypothesized that SI measured at higher probe-tone frequencies may provide a better distinction between healthy and otosclerotic ears. As expected, the results of this study indicate that SI measured at higher probe-tone frequencies is superior to a standard low probe tone in the detection of otosclerotic ears. Through systematic and objective comparisons of relevant probe-tone frequencies using both group statistics and test performance analysis, the present study suggests 630 Hz as an optimum probe-tone frequency for measuring SI with respect to distinguishing healthy ears from otosclerotic ears.
29
Ruggero, M. A., L. Robles e N. C. Rich. "Two-tone suppression in the basilar membrane of the cochlea: mechanical basis of auditory-nerve rate suppression". Journal of Neurophysiology 68, n. 4 (1 ottobre 1992): 1087–99. http://dx.doi.org/10.1152/jn.1992.68.4.1087.
Testo completoAbstract (sommario):
1. The vibratory response to two-tone stimuli was measured in the basilar membrane of the chinchilla cochlea by means of the Mossbauer technique or laser velocimetry. Measurements were made at sites with characteristic frequency (CF, the frequency at which an auditory structure is most sensitive) of 7-10 kHz, located approximately 3.5 mm from the oval window. 2. Two-tone suppression (reduction in the response to one tone due to the presence of another) was demonstrated for CF probe tones and suppressor tones with frequencies both higher and lower than CF, at moderately low stimulus levels, including probe-suppressor combinations for which responses to the suppressor were lower than responses to the probe tone alone. 3. For a fixed suppressor tone, suppression magnitude decreased as a function of increasing probe intensity. 4. The magnitude of suppression increased monotonically with suppressor intensity. 5. The rate of growth of suppression magnitude with suppressor intensity was higher for suppressors in the region below CF than for those in the region above CF. 6. For low-frequency suppressor tones, suppression magnitude varied periodically, attaining one or two maxima within each period of the suppressor tone. 7. Suppression was frequency tuned: for either above-CF or below-CF suppressor tones, suppression magnitude reached a maximum for probe frequencies near CF. 8. Cochlear damage or death diminished or abolished suppression. There was a clear positive correlation between magnitude of suppression and basilar-membrane sensitivity for responses to CF tones. 9. Suppression tended to be accompanied by small phase lags in responses to CF probe tones. 10. Because all of the features of two-tone suppression at the basilar membrane match qualitatively (and, generally, also quantitatively) the features of two-tone rate suppression in auditory-nerve fibers, it is concluded that neural two-tone rate suppression originates in mechanical phenomena at the basilar membrane. 11. Because the lability of mechanical suppression parallels the loss of sensitivity and frequency tuning due to outer hair cell dysfunction, the present findings suggest that mechanical two-tone suppression arises from an interaction between the outer hair cells and the basilar membrane.
30
Funasaka, Sotaro, e Kozo Kumakawa. "Tympanometry using a Sweep-Frequency Probe Tone and Its Clinical Evaluation". International Journal of Audiology 27, n. 2 (gennaio 1988): 99–108. http://dx.doi.org/10.3109/00206098809081580.
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Nielsen, Lars Holme, Gerald R. Popelka, Arne Nørby Rasmussen e Poul Aabo Osterhammel. "Clinical Significance of Probe-tone Frequency Ratio on Distortion Product Otoacoustic Emissions". Scandinavian Audiology 22, n. 3 (gennaio 1993): 159–64. http://dx.doi.org/10.3109/01050399309047462.
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Laskar, J. "Cryogenic vacuum high frequency probe station". Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures 8, n. 5 (settembre 1990): 1161. http://dx.doi.org/10.1116/1.584936.
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Smith, D. C. "Balanced probe extends high-frequency measurements". IEEE Circuits and Devices Magazine 10, n. 6 (novembre 1994): 19–23. http://dx.doi.org/10.1109/101.329929.
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Lee, Guo-She, Ching-Ping Wang e Sherry Fu. "Evaluation of Hypernasality in Vowels Using Voice Low Tone to High Tone Ratio". Cleft Palate-Craniofacial Journal 46, n. 1 (gennaio 2009): 47–52. http://dx.doi.org/10.1597/07-184.1.
Testo completoAbstract (sommario):
Objective: The voice low tone to high tone ratio (VLHR) is defined as the power ratio of low frequency to high frequency energy obtained by dividing the voice spectrum with a specific cutoff frequency. In a previous study, VLHR correlated significantly with nasalance and perceptual rating of hypernasality for a single vowel. The methodology was optimized in this study by investigating the correlations among other vowels. Design: Voice signals of six sustained vowels vocalized by subjects with hypernasality were collected. Vowel nasalance was obtained with a nasometer, and hypernasality rating scores were provided by two speech-language pathologists. The VLHRs calculated using different cutoff frequencies were correlated with nasalance and hypernasality rating scores. Participants: Eight subjects with hypernasality caused by palatal fistula or velopharyngeal insufficiency. Main Outcome Measures: VLHR, nasalance, and hypernasality rating score. Results: The correlation of VLHR with nasalance and hypernasality rating was most significant using a cutoff frequency of 600 Hz. The correlation of VLHR with nasalance was significant (r = .62, p < .01, Pearson's correlation), as was the correlation of VLHR with hypernasality score (Spearman's rank correlation coefficient = .62, p < .01). Conclusions: VLHR correlated significantly with nasalance and hypernasality in the six sustained vowels and may provide another quantitative index for the evaluation of hypernasality in sustained vowels.
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Shibuya, Shohei, Tomonori Yanagida, Koji Asami e Haruo Kobayashi. "High-Frequency Low-Distortion One-Tone and Two-Tone Signal Generation Using Arbitrary Waveform Generator". Applied Mechanics and Materials 888 (febbraio 2019): 52–58. http://dx.doi.org/10.4028/www.scientific.net/amm.888.52.
Testo completoAbstract (sommario):
This paper describes analysis, simulation and experiment verification of high-frequency one-tone and two-tone low-distortion signal generation methods with an arbitrary waveform generator (AWG) for analog/mixed-signal IC testing. Our previously proposed phase switching method was limited to low-frequency signal generation, and it cannot be used directly for high-frequency signal generation. We propose here a method for generating a low-distortion high-frequency signal (i.e., the frequency close to the Nyquist frequency of the AWG) with an AWG, and show its theoretical analysis and simulation results. With this proposed method, 3rd order harmonics of the generated signal are suppressed simply by changing the AWG program (or waveform memory contents)—AWG nonlinearity identification is not required—and spurious components, generated far from the signal band, are relatively easy to remove using an analog filter.
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Bragin, Denis E., Gloria L. Statom, Sean Hagberg e Edwin M. Nemoto. "Increases in microvascular perfusion and tissue oxygenation via pulsed electromagnetic fields in the healthy rat brain". Journal of Neurosurgery 122, n. 5 (maggio 2015): 1239–47. http://dx.doi.org/10.3171/2014.8.jns132083.
Testo completoAbstract (sommario):
OBJECT High-frequency pulsed electromagnetic field stimulation is an emerging noninvasive therapy being used clinically to facilitate bone and cutaneous wound healing. Although the mechanisms of action of pulsed electromagnetic fields (PEMF) are unknown, some studies suggest that its effects are mediated by increased nitric oxide (NO), a well-known vasodilator. The authors hypothesized that in the brain, PEMF increase NO, which induces vasodilation, enhances microvascular perfusion and tissue oxygenation, and may be a useful adjunct therapy in stroke and traumatic brain injury. To test this hypothesis, they studied the effect of PEMF on a healthy rat brain with and without NO synthase (NOS) inhibition. METHODS In vivo two-photon laser scanning microscopy (2PLSM) was used on the parietal cortex of rat brains to measure microvascular tone and red blood cell (RBC) flow velocity in microvessels with diameters ranging from 3 to 50 μm, which includes capillaries, arterioles, and venules. Tissue oxygenation (reduced nicotinamide adenine dinucleotide [NADH] fluorescence) was also measured before and for 3 hours after PEMF treatment using the FDA-cleared SofPulse device (Ivivi Health Sciences, LLC). To test NO involvement, the NOS inhibitor NG-nitro-l-arginine methyl ester (L-NAME) was intravenously injected (10 mg/kg). In a time control group, PEMF were not used. Doppler flux (0.8-mm probe diameter), brain and rectal temperatures, arterial blood pressure, blood gases, hematocrit, and electrolytes were monitored. RESULTS Pulsed electromagnetic field stimulation significantly dilated cerebral arterioles from a baseline average diameter of 26.4 ± 0.84 μm to 29.1 ± 0.91 μm (11 rats, p < 0.01). Increased blood volume flow through dilated arterioles enhanced capillary flow with an average increase in RBC flow velocity by 5.5% ± 1.3% (p < 0.01). Enhanced microvascular flow increased tissue oxygenation as reflected by a decrease in NADH autofluorescence to 94.7% ± 1.6% of baseline (p < 0.05). Nitric oxide synthase inhibition by L-NAME prevented PEMF-induced changes in arteriolar diameter, microvascular perfusion, and tissue oxygenation (7 rats). No changes in measured parameters were observed throughout the study in the untreated time controls (5 rats). CONCLUSIONS This is the first demonstration of the acute effects of PEMF on cerebral cortical microvascular perfusion and metabolism. Thirty minutes of PEMF treatment induced cerebral arteriolar dilation leading to an increase in microvascular blood flow and tissue oxygenation that persisted for at least 3 hours. The effects of PEMF were mediated by NO, as we have shown in NOS inhibition experiments. These results suggest that PEMF may be an effective treatment for patients after traumatic or ischemic brain injury. Studies on the effect of PEMF on the injured brain are in progress.
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Fausti, Stephen A., Deanna J. Olson, Richard H. Frey, James A. Henry e Heidi I. Schaffer. "High-Frequency Tone Burst-Evoked ABR Latency-Intensity Functions". Scandinavian Audiology 22, n. 1 (gennaio 1993): 25–33. http://dx.doi.org/10.3109/01050399309046015.
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Payne, S. J., e A. J. W. Moxon. "High-Frequency Effects in the Aspirating Probe". Journal of Turbomachinery 129, n. 4 (9 ottobre 2006): 842–51. http://dx.doi.org/10.1115/1.2720872.
Testo completoAbstract (sommario):
The aspirating probe has recently been successfully used to measure entropy within a turbomachine; however, it was found that its sensitivity to total pressure and total temperature fluctuations was significantly altered at high frequencies. If the aspirating probe is to be used to measure unsteady flow fields accurately, these high-frequency effects must be better understood. The analysis of this behavior presented here shows that there are three effects that must be considered: the frequency response of the hot wires, the presence of Mach number fluctuations inside the probe, and the change in heat transfer from the hot wires at high frequencies. A theoretical analysis of the first effect has provided a correction factor that can be used for any hot wire, dependent solely on the baseline heat transfer ratio, the overheat ratio, and the time constant of the hot wires. The second and third effects have been examined numerically, since no theoretical solution is known to exist. The Mach number fluctuations are found to be well predicted by a simple one-dimensional solver and to show a variation of ±2.4% in Mach number at the hot-wire plane for the geometry and flow field considered here. The variation in heat transfer with frequency is found to be negligible at high overheat ratios, but significant at overheat ratios below ∼0.4. Coefficients that determine how the measured total pressure and total temperature depend on the actual total pressure, total temperature, and Mach number have been derived, and these show significant variation with the values of the two overheat ratios. Using synthetic data, based on previous experimental data, the effects on the probe measurement accuracy are analyzed. This shows that the amplitudes of total pressure and total temperature are reduced. At widely spaced overheat ratios, the amplitudes are reduced by similar amounts, but at smaller spacing the reductions become dissimilar, resulting in highly erroneous entropy∕R measurements. High-frequency effects thus have a significant effect on the performance of the aspirating probe and should be carefully considered when using it in a highly unsteady flow field.
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Lindberg, L. "High-frequency probe circuits for plasma diagnostics". Journal of Physics E: Scientific Instruments 18, n. 3 (marzo 1985): 214–17. http://dx.doi.org/10.1088/0022-3735/18/3/011.
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Rabjohn, G., J. Wolczanski e R. Surridge. "High-frequency wafer-probing techniques". Canadian Journal of Physics 65, n. 8 (1 agosto 1987): 850–55. http://dx.doi.org/10.1139/p87-130.
Testo completoAbstract (sommario):
High-speed digital and microwave circuits have traditionally been tested by dicing wafers and mounting chips into high-frequency test carriers. This process is expensive, time consuming, and destructive. Methods of high-frequency measurement at the wafer stage are very desirable; for example, for wafer mapping, but conventional needle probes cannot be used because of their parasitics. New probe structures based on fine coaxial lines, vertically mounted microstrip lines, and tapered coplanar lines have been reported.For measurement at microwave frequencies (2–20 GHz), we have developed a geometry of a coplanar wave-guide probe that gives better than 10 dB return loss. Individual monolithic components can easily be measured and modelled for inclusion in a circuit simulation.For the measurement of digital circuits, especially those requiring several high-speed signal lines, we have used proprietary microstrip probes. Satisfactory operation up to about 2 Gbit∙s−1 has been observed, the upper bit rate being restricted by the inductance of the probe tip.Microwave-frequency and time-domain measurements of both types of probes have been made and will be discussed. Additionally, examples of the use of these probes for on-wafer measurements of digital and analog circuits will be given.
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Brosch, Michael, e Christoph E. Schreiner. "Time Course of Forward Masking Tuning Curves in Cat Primary Auditory Cortex". Journal of Neurophysiology 77, n. 2 (1 febbraio 1997): 923–43. http://dx.doi.org/10.1152/jn.1997.77.2.923.
Testo completoAbstract (sommario):
Brosch, Michael and Christoph E. Schreiner. Time course of forward masking tuning curves in cat primary auditory cortex. J. Neurophysiol. 77: 923–943, 1997. Nonsimultaneous two-tone interactions were studied in the primary auditory cortex of anesthetized cats. Poststimulatory effects of pure tone bursts (masker) on the evoked activity of a fixed tone burst (probe) were investigated. The temporal interval from masker onset to probe onset (stimulus onset asynchrony), masker frequency, and intensity were parametrically varied. For all of the 53 single units and 58 multiple-unit clusters, the neural activity of the probe signal was either inhibited, facilitated, and/or delayed by a limited set of masker stimuli. The stimulus range from which forward inhibition of the probe was induced typically was centered at and had approximately the size of the neuron's excitatory receptive field. This “masking tuning curve” was usually V shaped, i.e., the frequency range of inhibiting masker stimuli increased with the masker intensity. Forward inhibition was induced at the shortest stimulus onset asynchrony between masker and probe. With longer stimulus onset asynchronies, the frequency range of inhibiting maskers gradually became smaller. Recovery from forward inhibition occurred first at the lower- and higher-frequency borders of the masking tuning curve and lasted the longest for frequencies close to the neuron's characteristic frequency. The maximal duration of forward inhibition was measured as the longest period over which reduction of probe responses was observed. It was in the range of 53–430 ms, with an average of 143 ± 71 (SD) ms. Amount, duration and type of forward inhibition were weakly but significantly correlated with “static” neural receptive field properties like characteristic frequency, bandwidth, and latency. For the majority of neurons, the minimal inhibitory masker intensity increased when the stimulus onset asynchrony became longer. In most cases the highest masker intensities induced the longest forward inhibition. A significant number of neurons, however, exhibited longest periods of inhibition after maskers of intermediate intensity. The results show that the ability of cortical cells to respond with an excitatory activity depends on the temporal stimulus context. Neurons can follow higher repetition rates of stimulus sequences when successive stimuli differ in their spectral content. The differential sensitivity to temporal sound sequences within the receptive field of cortical cells as well as across different cells could contribute to the neural processing of temporally structured stimuli like speech and animal vocalizations.
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Psillas, George, Aikaterini Rizou, Dimitrios Rachovitsas, Gabriel Tsiropoulos e Jiannis Constantinidis. "Hearing Outcome of Low-tone Compared to High-tone Sudden Sensorineural Hearing Loss". International Archives of Otorhinolaryngology 23, n. 01 (19 giugno 2018): 065–69. http://dx.doi.org/10.1055/s-0038-1657789.
Testo completoAbstract (sommario):
Introduction Low-tone sudden sensorineural hearing loss (SSHL) is a well-recognized disease, in which the hearing loss is restricted to low frequencies. In contrast to low-tone SSHL, high-tone SSHL is characterized by high-frequency (4,000, 8,000 Hz) hearing loss and preservation of low-, middle-frequency hearing. Objective The objective of this study is to compare the hearing recovery and long-term outcome of low-tone SSHL with those of patients affected by high-tone SSHL in a follow-up of ∼ 3 years. Methods The low-tone SSHL and high-tone SSHL groups included 27 and 20 patients, respectively; the patients of both groups were treated with intravenous steroids. Predictive factors (gender, affected side, delay of treatment, follow-up time) were also examined. Results Overall, complete hearing recovery was observed in 77.7% of the patients in the low-tone SSHL group and in 15% of the patients in the high-tone SSHL group. In the high-tone SSHL group, a higher proportion of patients reported tinnitus compared with the low-tone SSHL group (13 cases [65%] versus 3 cases [11%]); however, recurrences were more common in the low-tone SSHL (22%, 6 patients) compared with the high-tone SSHL (2 cases [10%]) group. No predictive factor was found to statistically impact on hearing outcome. Conclusion After initial therapy, the low-tone SSHL patients have more favorable hearing outcome than high-tone SSHL patients. However, recurrences occurred more frequently in the low-tone SSHL group, while the high-tone SSHL group was more often accompanied by residual symptoms, such as tinnitus.
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Bulla, Wesley. "Detection of High-Frequency Harmonics in a Brief Complex Tone". Journal of the Audio Engineering Society 64, n. 1/2 (5 febbraio 2016): 4–12. http://dx.doi.org/10.17743/jaes.2015.0086.
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Puckett, Amanda C., Pritesh K. Pandya, Raluca Moucha, WeiWei Dai e Michael P. Kilgard. "Plasticity in the Rat Posterior Auditory Field Following Nucleus Basalis Stimulation". Journal of Neurophysiology 98, n. 1 (luglio 2007): 253–65. http://dx.doi.org/10.1152/jn.01309.2006.
Testo completoAbstract (sommario):
Classical conditioning paradigms have been shown to cause frequency-specific plasticity in both primary and secondary cortical areas. Previous research demonstrated that repeated pairing of nucleus basalis (NB) stimulation with a tone results in plasticity in primary auditory cortex (A1), mimicking the changes observed after classical conditioning. However, few studies have documented the effects of similar paradigms in secondary cortical areas. The purpose of this study was to quantify plasticity in the posterior auditory field (PAF) of the rat after NB stimulation paired with a high-frequency tone. NB–tone pairing increased the frequency selectivity of PAF sites activated by the paired tone. This frequency-specific receptive field size narrowing led to a reorganization of PAF such that responses to low- and mid-frequency tones were reduced by 40%. Plasticity in A1 was consistent with previous studies—pairing a high-frequency tone with NB stimulation expanded the high-frequency region of the frequency map. Receptive field sizes did not change, but characteristic frequencies in A1 were shifted after NB–tone pairing. These results demonstrate that experience-dependent plasticity can take different forms in both A1 and secondary auditory cortex.
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Pelletier, Mathew, Robert Schwartz, Greg Holt, John Wanjura e Timothy Green. "Frequency Domain Probe Design for High Frequency Sensing of Soil Moisture". Agriculture 6, n. 4 (11 novembre 2016): 60. http://dx.doi.org/10.3390/agriculture6040060.
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Enpuku, K., S. Hijiya e A. Nakahodo. "Josephson junction array for high-frequency current probe". Physica C: Superconductivity 367, n. 1-4 (febbraio 2002): 256–59. http://dx.doi.org/10.1016/s0921-4534(01)01047-4.
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Said, R. A., M. Mittal, G. E. Bridges e D. J. Thomson. "High frequency potential probe using electrostatic force microscopy". Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films 12, n. 4 (luglio 1994): 2591–94. http://dx.doi.org/10.1116/1.579063.
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Fox, V. L., L. Heard e K. Donovan. "HIGH FREQUENCY PROBE ULTRASONOGRAPHY IN CHILDREN: PRELIMINARY FINDINGS". Journal of Pediatric Gastroenterology & Nutrition 27, n. 4 (ottobre 1998): 476. http://dx.doi.org/10.1097/00005176-199810000-00074.
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Zarsav, N. "High Frequency Ultrasonic Measurements". Measurement and Control 21, n. 5 (giugno 1988): 133–36. http://dx.doi.org/10.1177/002029408802100501.
Testo completoAbstract (sommario):
The use of high frequency ultrasonic Lamb waves to measure the thickness of thin plates and foils, is discussed and the feasibility of their application to the determination of the degree of cure of polymer coating on coated tin plated steel sheet (as used by the food can industry) is evaluated. The paper also discusses briefly the design features of the purpose built precision double probe ultrasonic goniometer used to carry out these measurements.
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Valdizón-Rodríguez, Roberto, e Paul A. Faure. "Frequency tuning of synaptic inhibition underlying duration-tuned neurons in the mammalian inferior colliculus". Journal of Neurophysiology 117, n. 4 (1 aprile 2017): 1636–56. http://dx.doi.org/10.1152/jn.00807.2016.
Testo completoAbstract (sommario):
Inhibition plays an important role in creating the temporal response properties of duration-tuned neurons (DTNs) in the mammalian inferior colliculus (IC). Neurophysiological and computational studies indicate that duration selectivity in the IC is created through the convergence of excitatory and inhibitory synaptic inputs offset in time. We used paired-tone stimulation and extracellular recording to measure the frequency tuning of the inhibition acting on DTNs in the IC of the big brown bat ( Eptesicus fuscus). We stimulated DTNs with pairs of tones differing in duration, onset time, and frequency. The onset time of a short, best-duration (BD), probe tone set to the best excitatory frequency (BEF) was varied relative to the onset of a longer-duration, nonexcitatory (NE) tone whose frequency was varied. When the NE tone frequency was near or within the cell’s excitatory bandwidth (eBW), BD tone-evoked spikes were suppressed by an onset-evoked inhibition. The onset of the spike suppression was independent of stimulus frequency, but both the offset and duration of the suppression decreased as the NE tone frequency departed from the BEF. We measured the inhibitory frequency response area, best inhibitory frequency (BIF), and inhibitory bandwidth (iBW) of each cell. We found that the BIF closely matched the BEF, but the iBW was broader and usually overlapped the eBW measured from the same cell. These data suggest that temporal selectivity of midbrain DTNs is created and preserved by having cells receive an onset-evoked, constant-latency, broadband inhibition that largely overlaps the cell’s excitatory receptive field. We conclude by discussing possible neural sources of the inhibition. NEW & NOTEWORTHY Duration-tuned neurons (DTNs) arise from temporally offset excitatory and inhibitory synaptic inputs. We used single-unit recording and paired-tone stimulation to measure the spectral tuning of the inhibitory inputs to DTNs. The onset of inhibition was independent of stimulus frequency; the offset and duration of inhibition systematically decreased as the stimulus departed from the cell’s best excitatory frequency. Best inhibitory frequencies matched best excitatory frequencies; however, inhibitory bandwidths were more broadly tuned than excitatory bandwidths.