Academic literature on the topic 'Hearing levels – Measurement'

AbstractBackground Many apps have been developed for users to screen their hearing in their own home. The purpose of this study was to investigate the validity and efficiency of a self-assessed acceptable noise level (ANL) in comparison to the traditional ANL measurements.Research Design A within-subject repeated measures research design was utilized.Data Collection and Analysis Sixty-two adults with normal hearing were recruited from Auburn University and the surrounding community. ANLs were measured utilizing the traditional measurement as well as the self-assessed ANL via the Unitron uHear app.Results Within-subject repeated measures of variance revealed no significant differences between traditional ANL measurements and self-assessed ANL measurements. Significant differences were found for time required for testing in each condition, revealing self-assessed testing to be significantly faster.Conclusion The self-assessed ANL measurement via the Unitron uHear app is a valid and efficient measurement of ANL in adults with normal hearing.

Twenty-seven student musicians were surveyed regarding musical practice and playing habits, knowledge of hearing conservation practices, use of hearing protective devices (HPD), and the occurrence of tinnitus after exposure to loud music. In addition, noise exposure levels during practice and sporting events (football and basketball games) at which they played were monitored with a dosimeter simultaneously set to measure noise levels using the OSHA (1983) and NIOSH (1998) measurement criteria. Forty-eight percent of the subjects reported practicing or playing their instrument <10 hours a week. Most musicians (74%) reported having been taught about the effects of noise on hearing and health; however, less than a third used ear protection while playing their instruments, and those who did used it inconsistently. Sixty-three percent of subjects reported experiencing tinnitus after exposure to loud music. Finally, 8-hour time-weighted averages (TWA) and daily noise doses were significantly higher using the NIOSH measurement criteria than the OSHA measurement criteria. Both measurement criteria yielded values that exceeded a 100% daily noise dose for all subjects. Overall, these results indicate that university student directors and musicians appear to be at high risk for permanent noise-induced hearing loss secondary to excessive exposure to loud music. These results support the need for on-going hearing conservation programs to educate student musicians and student directors about the dangers of excessive exposure to loud music.

Clinical measurement of the loudness discomfort level (LDL) historically has been part of the hearing aid fitting procedure, and this clinical practice remains popular today. LDL measurements also are recommended in contemporary hearing aid fitting protocols. Yet, surveys show that many hearing aid users are dissatisfied with the loudness of their hearing aids. In this evidence-based review article, we evaluate the effectiveness of clinical LDL measurements. Specifically, we asked the question "Are the clinical measurements of LDL for adult patients predictive of aided acceptance and satisfaction of loudness for high inputs in the real world?" Nearly 200 articles were reviewed; three met the criteria set forth in this review. The evidence supported using unaided LDLs for selecting the maximum real-ear output of hearing aids. No study using aided LDLs or aided loudness verification met the criteria. The level of the evidence for the three articles using unaided LDLs was low; no higher than Level 4. The limited number of studies, the level of evidence, and the statistical power of the studies prevents us from making a strong recommendation concerning the clinical use of LDL measures. Additional research in this area, especially research employing randomized controlled trials would be a useful addition to this body of literature.

OBJECTIVES: The purpose of this study was to determine daily noise doses and 8-hour time weighted averages for rock band musicians, crew members, and spectators during a typical rehearsal and performance using both Occupational Safety and Health Administration (OSHA) and National Institute of Occupational Safety and Health (NIOSH) measurement criteria. DESIGN: Personal noise dosimetry was completed on five members of a rock band during one 2-hr rehearsal and one 4-hr performance. Time-weighted averages (TWA) and daily dose values were calculated using both OSHA and NIOSH criteria and compared to industry guidelines for enrollment in hearing conservation programs and the use of hearing protection devices. RESULTS: TWA values ranged from 84.3 to 90.4 dBA (OSHA) and from 90.0 to 96.4 dBA (NIOSH) during the rehearsal. The same values ranged from 91.0 to 99.7 dBA (OSHA) and 94.0 to 102.8 dBA (NIOSH) for the performance. During the rehearsal, daily noise doses ranged from 45.54% to 106.7% (OSHA) and from 317.74% to 1396.07% (NIOSH). During the performance, doses ranged from 114.66% to 382.49% (OSHA) and from 793.31% to 5970.15% (NIOSH). CONCLUSIONS: The musicians in this study were exposed to dangerously high levels of noise and should be enrolled in a hearing conservation programs. Hearing protection devices should be worn, especially during performances. The OSHA measurement criteria yielded values significantly more conservative than those produced by NIOSH criteria. Audiologists should counsel musician-patients about the hazards of excessive noise (music) exposure and how to protect their hearing.

AbstractThe electrically evoked stapedial reflex threshold (ESRT) has been shown to be a good predictor of upper stimulation level for cochlear implant recipients. Previous research has shown that the ESRT may be recorded at lower stimulation levels and with a higher incidence of success with the use of higher frequency probe tones (e.g., 678 and 1000 Hz) relative to the use of the conventional 226-Hz probe tone. Research has also shown that the acoustic reflex may be recorded at lower stimulus levels with the use of wideband reflectance when compared to the acoustic reflex threshold recorded with a conventional acoustic immittance measurement.The objective of this study was to compare the ESRT recorded with acoustic immittance and wideband reflectance measurements.A repeated measures design was used to evaluate potential differences in ESRTs with stimulation at an apical, middle, and basal electrode contact with the use of two different techniques, acoustic immittance measurement and wideband reflectance.Twelve users of Cochlear Nucleus cochlear implants were included in the study.Participants’ ESRTs were evaluated in response to simulation at three different electrode contact sites (i.e., an apical, middle, and basal electrode contact) with the use of two different middle ear measurement techniques, acoustic immittance with the use of a 226-Hz probe tone and wideband reflectance with the use of a chirp stimulus.The mean ESRT recorded with wideband reflectance measurement was significantly lower when compared to the ESRT recorded with acoustic immittance. For one participant, the ESRT was not recorded with acoustic immittance before reaching the participant’s loudness discomfort threshold, but it was successfully recorded with the use of wideband reflectanceThe ESRT may potentially be recorded at lower presentation levels with the use of wideband reflectance measures relative to the use of acoustic immittance with a 226-Hz probe tone. This may allow for the ESRT to be obtained at levels that are more comfortable for the cochlear implant recipient, which may also allow for a higher incidence in the successful recording of the ESRT.

Fireworks are used all over the world to celebrate special occasions. Noise produced by firecrackers that are used to celebrate these occasions has been highlighted. This impulse type of noise can cause hearing damage. Noise measurements of firecrackers show that they produce high sound pressure peak levels. Typical firecracker impulse noise levels are given. Noise limits and measurement methods used for the fireworks in some countries are presented.

Background: In-situ audiometry is a hearing aid feature that enables the measurement of hearing threshold levels through the hearing instrument using the built-in sound generator and the hearing aid receiver. This feature can be used in hearing aid fittings instead of conventional pure-tone audiometry (PTA), particularly in places where no standard audiometric equipment is available. Differences between conventional and in-situ thresholds are described and discussed for some particular hearing aids. No previous investigation has measured and compared these differences for a number of current hearing aid models by various manufacturers across a wide range of hearing losses. Purpose: The purpose of this study was to perform a model-based comparison of conventionally and in-situ measured hearing thresholds. Data were collected for a range of hearing aid devices to study and generalize the effects that may occur under clinical conditions. Research Design: Research design was an experimental and regression study. Study Sample: A total of 30 adults with sensorineural hearing loss served as test persons. They were assigned to three subgroups of 10 subjects with mild (M), moderate to severe (MS), and severe (S) sensorineural hearing loss. Intervention: All 30 test persons underwent both conventional PTA and in-situ audiometry with four hearing aid models by various manufacturers. Data Collection and Analysis: The differences between conventionally and in-situ measured hearing threshold levels were calculated and evaluated by an exploratory data analysis followed by a sophisticated statistical modeling process. Results: At 500 and 1500 Hz, almost all threshold differences (conventional PTA minus in-situ data) were negative, i.e., in the low to mid frequencies, hearing loss was overestimated by most devices relative to PTA. At 4000 Hz, the majority of differences (7 of 12) were positive, i.e., in the frequency range above 1500 Hz, hearing loss was frequently underestimated. As hearing loss increased (M→MS→S), the effect of the underestimation decreased. At 500 and 1500 Hz, Resound devices showed the smallest threshold deviations, followed by Phonak, Starkey, and Oticon instruments. At 4000 Hz, this observed pattern partly disappeared and Starkey and Oticon devices showed a reversed effect with increasing hearing loss (M→MS→S). Because of high standard errors for the estimates, only a few explicit rankings of the devices could be established based on significant threshold differences (5% level). Conclusions: Differences between conventional PTA and in-situ threshold levels may be attributed to (1) frequency, (2) device/hearing loss, and (3) calibration/manufacturer effects. Frequency effects primarily resulting in an overestimation of hearing loss by in-situ audiometry in the low and mid frequencies are mainly due to sound drain-off through vents and leaks. Device/hearing loss effects may be due to leakage as well as boundary effects because in-situ audiometry is confined to a limited measurement range. Finally, different calibration approaches may result in different offset levels between PTA and in-situ audiometry calibration. In some cases, the observed threshold differences of up to 10–15 dB may translate to varied hearing aid fittings for the same user depending on how hearing threshold levels were measured.

High levels of occupational noise exposure increase the risk of hearing difficulties and tinnitus. However, differences in demographic, health, and lifestyle factors could also contribute to high levels of hearing difficulties and tinnitus in some industries. Data from a subsample ( n = 22,936) of the U.K. Biobank were analyzed to determine to what extent differences in levels of hearing difficulties and tinnitus in high-risk industries (construction, agricultural, and music) compared with low-risk industries (finance) could be attributable to demographic, health, and lifestyle factors, rather than occupational noise exposure. Hearing difficulties were identified using a digits-in-noise speech recognition test. Tinnitus was identified based on self-report. Logistic regression analyses showed that occupational noise exposure partially accounted for higher levels of hearing difficulties in the agricultural industry compared with finance, and occupational noise exposure, older age, low socioeconomic status, and non-White ethnic background partially accounted for higher levels of hearing difficulties in the construction industry. However, the factors assessed in the model did not fully account for the increased likelihood of hearing difficulties in high-risk industries, suggesting that there are additional unknown factors which impact on hearing or that there was insufficient measurement of factors included in the model. The levels of tinnitus were greatest for music and construction industries compared with finance, and these differences were accounted for by occupational and music noise exposure, as well as older age. These findings emphasize the need to promote hearing conservation in occupational and music settings, with a particular focus on high-risk demographic subgroups.

The impact of tinnitus and overall levels of distress were measured with three assessment tools for patients with tinnitus. The Tinnitus Handicap Inventory (THI), the Symptom Checklist-90-Revised (SCL-90-R) and an activities limitations questionnaire were administered to 53 audiology patients reporting tinnitus. Forty-three percent of these patients experienced either quality of life reductions associated with tinnitus, substantial perceived handicap, and/or a high level of distress. Results from the General Severity Index (GSI) of the SCL-90-R indicated that 25% of these patients displayed distress greater than that of the general medical population. The SCL-90-R can be a useful tool for audiologists working with tinnitus patients in assessing needs for referral for psychological or psychiatric counseling.

The acoustic reflex refers to the contraction of a middle ear muscle in response to sound. The contraction causes a stiffening of the middle ear system and, consequently, the flow of acoustic energy to the cochlea is impeded. By measuring the change in admittance in the auditory system during sound stimulation it is possible to indirectly monitor the middle ear muscle contractions. Such measurements provide useful information regarding the integrity of the auditory system and the location of the auditory pathology.

Federal regulations specify that an employee working for eight hours cannot legally be exposed to noise which has a time-weighted average greater than 90 decibels on the A scale. The industrial workforce is comprised of not only people with normal hearing acuity, but of individuals who suffer from hearing loss. While current noise regulation standards are deemed appropriate for those with normal hearing, it is difficult to apply these standards to persons wearing hearing aids on the job. The ambient, or unamplified, noise levels that fall below the maximum permitted by OSHA standards may very well be amplified to levels greater than 90 dBA, by the hearing aid. If this were the case, the company employing the hearing aid user would technically be in violation of the OSHA regulations. This study addressed the question of what noise exposure might be expected for hearing aid users on the job in different situations, as well as in non-vocational settings. The research involved two methods, conducted to determine the noise levels created by hearing aids with different amounts of gain and to determine whether the amplified noise levels exceed those requiring intervention under current regulations. For both methods, ambient and amplified noise levels for each condition were gathered in specified increments, and were compared with regard to current regulatory standards. The resultant data revealed that when ambient noise levels average between 80 and 84 dBA, amplification provided by even a mild gain hearing aid caused the eight hour time-weighted averages (TWA's) to increase to levels above the 90 dBA maximum permissible levels as delineated by OSHA. Moderate and high gain aids further increased these levels. The results of this study suggest that the hearing aid users in industrial and perhaps non-industrial settings may very well be exposed to intensity levels which exceed OSHA maximums, even when ambient levels do not. The extent to which these arc exceeded are based on the gain and output of the hearing aid in use.

Electrophysiological measures such as impedance telemetry and Neural Response Telemetry (NRT™) were developed by Cochlear™ in 1992 as clinical tools allowing the objective setting of stimulus levels for cochlear implant users. Extensive research proved the usefulness of NRT™’s as an aid in the programming process of audible and comfortable stimulus levels for children younger than six years. The Nucleus® Freedom™, launched in 2005, introduced new developments in cochlear implantation. Approval from the FDA for this system was obtained in March 2005 and for the first time included children from age 12 months with profound hearing loss. The Joint Committee on Infant Hearing suggested that children be diagnosed and that treatment commenced by the age of six months. The new features of the Nucleus Freedom™ give clinicians the necessary tools to treat this challenging population. An urgent need exists to ascertain the stability and accuracy of the new features introduced by this system, especially the Auto-NRT™ software, to validate its use within the paediatric population. A longitudinal descriptive design was utilized implementing quantitative research methods to critically describe the behaviour of impedance telemetry and NRT™’s in a group of young cochlear implant users. The quantitative method included the application of the Custom Sound™ software and the Auto-NRT™ feature for this group at implantation, device activation, and then at determined follow-up visits. Nine young children between nine months and five years and eleven months were used as participants during the twelve months of research. Impedance telemetry was described in terms of the mean Common Ground (CG) and Monopolar 1+2 (MP1+2) values calculated from measurement data collected on the basal, medial, and apical electrodes of the electrode array. The electrodes identified for statistical procedures for both measurement types were E3, E6, E8, E11, E13, E16, E19 and E21. Friedman’s ANOVA was used as a statistical measure to determine the level of significance in changes among the measurement modes and conditions. The Wilcoxon signed-rank test was indicated in the presence of significant changes identified by Friedman’s ANOVA to calculate the level of significance in a pair-wise comparison. Results indicate that impedance telemetry remained consistent over the electrode array and over time in both measurement modes. A slight increase in mean values was observed during the first three months, followed by a gradual decrease at the six months interval. These changes were statistically nonsignificant. No specific trends were evident in impedance telemetry over time. NRT™-measurements remained consistent across the electrode array over time. Significant changes were present between the intra-operative to device activation measurement intervals. This trend is also described in studies of adult cochlear implant users. NRT™-measurements were stable during the first year postimplantation within the paediatric population. A comparison between the mean impedance telemetry and NRT™’s disclosed an inverse trend during the first six months post-implantation. Most changes were non-significant, indicating that these measures can be used effectively in the new semi-automated fitting software. The implementation of these measurements can lead to streamlined and accountable service delivery to young cochlear implant users. AFRIKAANS : In 1992 is elektrofisiologiese metings soos impedanstelemetrie en Neurale Respons Telemetrie (NRT™) deur Cochlear™ ontwikkel as kliniese hulpmiddels om objektiewe instelling van stimulasievlakke vir kogleêre gebruikers moontlik te maak. Navorsing het bewys dat NRT™’s ‘n effektiewe hulpmiddel is tydens programmering van hoorbare en gemaklike stimulasievlakke by kinders jonger as ses jaar. Die Nucleus® Freedom™ met nuwe ontwikkelings ten opsigte van kogleêre inplantings is in 2005 bekendgestel. Die FDA het in Maart 2005 hierdie sisteem goedgekeur vir gebruik by kinders selfs so jonk as 12 maande met uitermatige gehoorverlies. Die Joint Committee on Infant Hearing het voorgestel dat diagnose en aanvang van rehabilitasie teen ses maande ouderdom moet plaasvind. Die nuwe funksies van die Nucleus® Freedom™ stel oudioloë in staat om hierdie uitdagende bevolking te hanteer. ‘n Dringende behoefte bestaan om te bepaal of hierdie sagteware, veral Auto-NRT™ wat saam met hierdie sisteem bekendgestel is, oor voldoende akkuraatheid en stabiliteit beskik om in die hantering van die pediatriese bevolking te gebruik. ‘n Longitudinale, beskrywende ontwerp, wat kwantitatiewe metodes implementeer, is aangewend om die beweging van impedanstelemetrie en NRT™’s by ‘n groep jong gebruikers van kogleêre inplantings krities te beskryf. Dit het die gebruik van die Custom Sound™ sagteware en die ingeslote Auto- NRT™ funksie behels. Dit is tydens inplantering, by aktivering van die toestel, en bepaalde opvolgsessies uitgevoer. Nege jong kinders tussen die ouderdomme van nege maande en vyf jaar en 11 maande is tydens die 12 maande navorsingsperiode as proefpersone benut. Die impedansmetings is beskryf in terme van die Common Ground (CG) en Monopolar 1+2 (MP1+2) stimulasiemodaliteite. Data is verkry vanaf geselekteerde elektrodes op die basale, mediale en apikale gedeeltes van die elektrode. Vir statistiese ontledings van impedans en NRT™ is hierdie elektrodes geselekteer: E3, E6, E8, E11, E13 E16, E19 en E21. As statistiese ontledingsmetode, is Friedman se ANOVA toegepas om die vlakke van beduidenheid van beweging tussen die verskillende toetsmodaliteite en -omstandighede te bepaal. Die Wilcoxon signed-rank toets is aangedui in die teenwoordigheid van statisties beduidende veranderinge. Die doel van hierdie toets was om die vlak van beduidenheid paarsgewys te verifieer. Resultate dui op konstante impedansmetings oor die elektrode asook oor tyd in beide toetsmodaliteite. ‘n Geringe, statisties nie-beduidende, verhoging in gemiddelde waardes is waargeneem tydens die eerste drie maande na inplantering, waarna die waardes weer geleidelik afgeneem het tot en met die ses maande opvolginterval. Geen spesifieke neiging kon vir impedanstelemetrie bepaal word nie. NRT™-metings het konstant gebly oor die elektrode en met tyd. Statisties beduidende veranderinge is gemeet tussen die intra-operatiewe en aktiveringsintervalle. Hierdie neiging is ook beskryf in studies van volwasse gebruikers van kogleêre inplantings. NRT™-metings, binne die pediatriese populasie, het dus stabiel gebly oor die 12 maande periode post-inplantering. ‘n Vergelyking tussen die gemiddelde impedans- en NRT™-metings het ‘n inverse neiging geïdentifiseer gedurende die eerste ses maande na inplantering. Veranderinge was oor die algemeen statisties nie-beduidend, wat daarop dui dat hierdie metings effektief gebruik kan word. Die implementering van hierdie metings kan meer doeltreffende dienslewering aan die jong gebruikers van kogleêre inplantings tot gevolg hê.
Dissertation (MCommunication Pathology)--University of Pretoria, 2010.
Speech-Language Pathology and Audiology
unrestricted

Background The noise-exposed population in the mining industry in South Africa poses unique problems to the occupational audiologist working in this environment, due to the broad linguistic and cultural diversity in the audiology and mining environment. Unfortunately, the problems are also exacerbated by a high incidence of pseudohypacusis within this population who are incentivised by compensation for NIHL. A solution to these specific problems would be the reliable and valid use of an objective test of function such as the DPOAE. The rationale for the study therefore was to extend the body of knowledge about the use of DPOAEs in the noise-exposed mining population. Methodology The current study was divided into two phases: phase one’s objectives entailed the investigation of the characteristics of DPOAEs in a noise-exposed mining population; phase two aimed to develop a multivariate regression model that would facilitate the prediction of the hearing threshold levels from the DPOAE levels in this population. Objectives The objectives in phase one of the study were to investigate the bivariate correlations between DPOAE levels and air-conduction hearing threshold levels in noise-exposed gold miners, for the three stimulus procedures. The study also aimed to investigate the bivariate correlations between various pure-tone averages (PTA) and the DPOAE averages of f2 frequencies closest to those pure-tone frequencies. Similarly, the Speech Recognition Thresholds (SRT) were correlated with DPOAE averages of f2 frequencies closest to the PTA. xx The study further aimed to investigate the characteristics of DPOAEs in noiseexposed gold miners by comparing the average DPOAE levels for different age category groups, different ethnic groups and for different occupation types. Finally, phase one aimed to describe the characteristics of emission level and noise floor differences (DP-NF) in a DPOAE database of a noise-exposed gold mining population. Phase two of the study had the objective of developing a multivariate prediction model using stepwise regression analysis to identify which of the DPOAE frequencies produced the best prediction of the audiogram frequencies when multivariate inputs were used for each stimulus procedure. The objective was also to evaluate the use of the predicted audiograms’ calculated percentage loss of hearing (PLH) with that of the actual PLH. This retrospective record review used an audiological database from a mine in the North West province of South Africa that contained 4800 records. The required sample size to be representative of the population was statistically determined. The records were randomly selected resulting a sample size for the FB2-S group of 161, for the FB1-S group of 177 and the FB1-S group of 155 respectively. The hearing loss characteristics in the samples ranged from normal to profound losses with the majority being mild to moderate hearing losses. Results The findings of phase one showed negative correlations ranging from -0.327 to -0.573 for Frequency Band 1- Replicated (FB1-R) between DPOAE levels and air conduction hearing threshold levels. Similarly, Frequency Band 1-Single (FB1-S) and Frequency Band 2-Single (FB2-S) also showed negative correlations (ranging from -0.203 to -0.609 and -0.274 to -0.738 respectively). These correlation strengths have been confirmed previously by other published studies. xxi Correlations between groups of frequencies on an audiogram and averaged match groups of DPOAE frequencies by intensity levels, both for PTA and SRT, ranged between -0.323 and -0.661. No statistically significant differences were found between the DPOAE measurements and ethnic groups of African and Caucasian (Sample size of 175 for FB1-S, 137 for FB1-R and 161 for FB2-S). No differences were found between the DPOAE levels and the occupation types of mining team members, stopers and drillers. There was, however, a relational finding of a progressive decrement of DPOAE intensity levels by decade of age increase (Sample size of 37 for FB1-S, 45 for FB1-R and 155 for FB2-S). Mean DP levels in this population ranged from 1.5 to -14 dB SPL, and mean NF levels in the sample ranged from 0.1 to -16.8 dB SPL with the mean DP-NF difference ranges form 0.4 to 9.3 dBSPL. More than 60% of the data collected resulted in a DP-NF of less than 10 dB SPL. The simple correlation relationship between hearing threshold levels and DPOAEs did not sufficiently explain the variance within the sample and due to the fact that a number of the independent variables in the sample were highly correlated, there was a call to use a method that allows for multicolinearity (i.e. stepwise regression analysis) in order to develop a prediction model. Consequently, phase two of the study was able to compare actual air-conduction hearing threshold levels with those calculated with the prediction model, and then calculate predicted percentage loss of hearing (PLH) with actual PLH found in the noise-exposed gold miners. In phase two, with the use of the predictive models, the predicted hearing threshold levels were found to differ from the actual thresholds by no more than 7dB HL across all frequencies (average of 5 dB HL for FB1-R, 2 dB HL for FB1-S and 3 dB HL for FB2-S). The differences for each audiogram frequency between the actual and the predicted thresholds are represented on scatter plots in phase two of the thesis. The PLH of the predicted audiograms was calculated using the weighted xxii tables prescribed by the Compensation for Occupational Diseases and Injuries Act (COIDA). A comparison of the predicted PLH with the actual PLH indicated that the predicted PLH ranged between minus 1.3% PLH and plus 6.7% PLH of the actual PLH. Results of the study are discussed with regards to the clinical implications, and the implications for training occupational audiologists in South Africa. The results of this study will improve and inform practice in the mining environment and in the field of compensation for NIHL. By developing a reliable prediction tool which is implemented on an objective test proven to document the extent of damage incurred from noise-exposure, a clinician will gain greater confidence in an accurate diagnosis, thereby further safeguarding a vulnerable population. The results from this study are highly relevant to the mining industry and will add value to the industrial development of South Africa by informing the policy on hearing conservation and compensation, thereby increasing the awareness of the need for improved occupational health and safety conditions and sustainable development in the mining industry.

As part of democratic liberalization in the late 1970s and 1980s, noise abatement signified the Kuomintang (KMT) regime’s attention to the quality of life of local Taiwanese residents. However, the use of scientific, objective indicators for noise, such as decibels, also had the effect of subjecting individual, human experience to the standardizing techniques of quantification and measurement. This chapter examines the application of Western technologies of audiometry and noise abatement in the context of Taiwan’s transition to a postauthoritarian state. Through an analysis of audiometric testing of hearing health among schoolchildren and neighborhood-wide socioacoustic surveys that assessed noise tolerance levels, this chapter asks how hearing and noise became interests of the state—as both a source of state authority and a symbol of liberal governance.

Noise exposure is a basic concept used to assess the risk of noise induced hearing loss in the workplace. It is very important, since loud noise is omnipresent in almost all human activity, especially in industry, construction, mining and transportation. The question to answer is how to determine the risk of a person performing in an environment where the noise levels, duration and frequency content change with time. The answer is obtained by measuring his noise exposure. Although the measurement itself is not complex or difficult, a proper knowledge of what exactly is the noise exposure and how to deal with the measurement result in fundamental to avoid getting wrong conclusions.

Dynamic measurement implies determining the content of signals having spectral structure and energy changing with time, sometimes on very short time scales. Dynamic measurements can present challenges to determine sufficient information in both the time and frequency domains. High resolution in frequency prevents finding short-term peak levels and recognizing true crest factors, and vice versa. If the dynamic measurement concerns sound, the much better simultaneous recognition of time and frequency information by the ear/brain than by conventional measurement methods can further complicate the challenge. People have at least three times better simultaneous time/frequency resolution than the familiar Fourier transform moved across the time axis, although quite often a compromise block size can be found that gives time/frequency measurement agreeing with human sound perception of both factors. Unlike technical measuring systems, human hearing is also very sensitive to patterns. The presence of tones, varying tones (amplitude and/or frequency), clicks, rattles, splashing sounds, etc., even at low levels in the presence of other less structured noise of considerably higher level, can dominate perception. Human consciousness effectively performs the opposite of averaging, ignoring the absolute value of slowly varying or stationary signals and focusing on things differing at short time bases from their surroundings in both time and frequency. In dynamic measurement it can be difficult to withdraw the important pattern from the absolute whole. Case studies will be given comparing conventional techniques with three high-resolution time/frequency methods useful in general engineering although developed to model the processes of human sound perception: a hearing model with very rapid time resolution at all frequencies [1], a relative (pattern) measurement technique subtracting a sliding average in both time and frequency from a running instantaneous spectrum [2], and a Fourier-based window deconvolution method giving pure spectral lines regardless of signal-to-block synchronization and permitting multiplication of frequency resolution for a given block length and time resolution [1], [3].

Measurements of the fluctuating wall pressure field across the transition region of a flat plate zero pressure gradient boundary layer have been performed with a 64-element linear array of sub-miniature hearing-aid microphones. The measurements provide a unique description of the formation, convection, and growth of turbulent spots in the transition zone and insight into a potential source of low-wavenumber energy. A model for the nonhomogeneous wavenumber-frequency spectrum has been formulated based on the observed spatio-temporal properties of the field. Measured array-averaged wavenumber-frequency spectral levels for the transitional boundary layer collapse with fully turbulent spectra in the vicinity of the convective ridge when scaled by intermittency, similar to previous findings for single point spectra. The transition zone convective ridge is broader, however, consistent with the notion of rapidly evolving (versus equilibrium) structures. Insight into the low-wavenumber portions of the spectra requires an improved array phase calibration. Wavelet based transform methods are being pursued to understand the evolution of spectral components during spot formation and to resolve the space-varying wavenumber content of the field.

This study suggests an attention economy perspective on incomplete information, asserting that people use partial information as basis for action, hence an effective information system should provide them just with the most useful partial information, and should avoid redundant information that wastes their limited attention resources. These assertions were empirically examined via simulation of a speech-reading process that measured the real and perceived value of two levels of partial speech-reading support. The findings indicate that additional partial information improved performance, but there was practically no significant difference between one and two signals support levels. High correlation was found between the different methods of evaluation, suggesting that perceived value may be used as substitute to real value measurement after considering the circumstances of the system involved. This research may provide important insights for designing information systems in general, as well as speech-reading support systems that will improve communication opportunities of hearing impaired people.

Noise presents itself today as the most frequent physical agent in the workplace and its harmfulness is already proven by the literature. Among its main consequences are noise-induced hearing loss that can be caused by any type of excessive sound emission, including those used in Spinning classes. The objective of the present study was to evaluate the sound pressure levels in Spinning classes in Brasília-DF academies, as well as to identify the teacher’s perception of their auditory condition. The Bruel & Kjaer 2250 sound pressure gauge was used to ensure the reliability of measurements. 43 teachers participated and the sound pressure levels were measured at 20 academies. The results indicate that 100% of the academies are working with values above the limits allowed by the current legislation (85dBA). Thus, the higher the weekly workload, the higher the maximum sound pressure level and the equivalent to which the teachers are exposed. Concerning the auditory perception of the teachers, (69.8%) they stated that they did not feel bothered by the loud sound. It is suggested that academies, teachers and students be guided to prevent possible hearing damage and to try to control the noise level in the classroom.

Introduction: Occupational noise is still a matter within the industrial practice with nefarious consequences on the worker’s health. Pulmonary diseases, cardiovascular problems, disturbances in sleep, fatigue, and, in the worst-case scenarios, hearing loss (this one with a permanent character) are some of the most common adverse effects reported in the literature. This issue covers itself in even more significant concern when analysing the mining industry context. Almost every operation works as a potential noise source, not only for the workers but also for the surrounding populations. Objective: To identify the exposure setting to occupational noise in the extractive industry and similar works (i.e. earthworks), particularly related to tasks and equipment. Methodology: The Preferred reporting items for systematic reviews and meta-analyses (PRISMA) was used as a guideline to help conduct the research and report of this work. The most relevant keywords were selected and later combined in the selected databases and multidisciplinary academic journals in the first phase. After, the articles were filtered with a set of exclusion criteria, to know: 1) Publication year, 2) Document type, 3) Source type, and 4) Language. The subsequent stage was to determine, within the remaining articles, the pertinence of each study and its later inclusion in the study. Each set of data was then classified according to the measurement context, and the results were analysed. Results and discussion: In the records’ identification phase, a total of 1148 papers were recovered. By applying the previously mentioned exclusion criteria, 547 were removed related to publication year, 146 due to document type, 12 related to source type and 25 because of language. Additionally, 360 records were excluded because were not in accordance with the proposed objective, 25 were duplicate articles, and 7 had no full-text available. From the last analysis, 11 more papers were excluded, which lead to a final result of 15 included studies. According to theoccupational noise measurements set, the records were divided into four categories: activity, equipment, job category, and working area. Different equipment was associated with high noise levels: crusher –between 85.6 and 104 dB, trucks and bulldozes –above 100 dB, and shovel –103 dB, whereas the only analysed activity was blasting, where studies concluded that increasing distance leads to lower noise measurement values. Conclusions: Considering this research, although it was possible to identify the tasks and equipment usually associated with occupational noise in the extractive industry, a lot of work still needs to be done, especially data analysis. However, this research serves as a starting point for future study.

Crowd noise levels in large stadiums are often discussed in the press and by the casual stadium patron; however, there has been little scientific evaluation of these levels and their corresponding effects. An effort was undertaken at Penn State University to measure noise on the field at Beaver Stadium (State College, PA: capacity 107,282) during a PSU football game. The two-fold purpose of these measurements was to evaluate the noise levels with respect to how they affect the game and make real-time, calibrated recordings for future use in the football team’s indoor practice facility. Measurements were taken on the field level using sound levels meters and DAT recorders throughout the PSU vs. Ohio State University football game on 27 October 2007. As a point of comparison, similar measurements were conducted by a team of researchers from Virginia Tech during the VT vs. University of Miami game on 17 November 2007 at Lane Stadium (Blacksburg, VA: capacity 66,233). The crowd noise levels are compared between the two stadiums taking into account the circumstances of the two games, time of day, and design of the stadiums. The levels on the field are evaluated in terms of speech intelligibility, i.e. the ability of the players to communicate with each other. In addition, a hearing loss safety assessment for both fans and players is presented.

Recently, traffic accidents due to drowsy driving, operation mistake in the power plant by drowsiness and decrease arousal in employment during work have been attracted as problems. To avoid such an accident, arousal level could be quantitatively evaluated in real time. We suggested that the one of the parameters of Duffing oscillator parameters is related to the conventional arousal level using the EEG frequency component. However, in this examination, effects on the EEG from visual and active behavior were considered, but those from hearing also need to be investigated. In this paper, we performed the experiment in the musical environment using rock and classic music to investigate the model parameters for effect of the auditory stimulation, and acquired EEG data in Visual cortex and Frontal lobe. The acquired EEG data was used to identify the model parameters, which were identified solving the inverse problem by Least Square method. Results of investigating correlation between conventional arousal revel and model parameter shows a significant correlation in case of the auditory environmental situation. Moreover, Visual cortex is better than Frontal lobe as a measurement point in this evaluation method.

There is interest in developing devices that mimic the sound transduction of the cochlear hair cells. Current artificial hair cell (AHC) designs have focused on passive transduction of sound into electrical signals. However, measurements inside living cochleae have revealed that a nonlinear amplification is at work in mammalian hearing. This amplification lowers the threshold for sound detection allowing mammals to hear faint sounds. The nonlinearity results in an amplitude compression whereby a large range of sound pressure levels produces a smaller range of displacements. This compressive nonlinearity gives the ear a large dynamic range. This work seeks to develop and analyze active artificial hair cells which employ a bio-inspired amplification to improve performance. This paper examines two artificial hair cell designs. The first is an 18.5 in long aluminum cantilever beam which is excited and controlled using piezoelectric actuators along the length of the beam. The second design is a one inch piezoelectric bimorph beam subject to a base excitation. In both cases a nonlinear feedback control law is implemented which reduces the beam’s linear viscous damping and introduces a cubic damping term. Model and experimental results show the control law amplified the response of the artificial hair cell to low excitation levels near the resonance frequency. Increasing input levels produced a compressive nonlinearity at resonance similar to that observed in measurements from mammalian cochleae. This work could lead to the development of new bio-inspired sensors with a lower threshold of detection, improved frequency sensitivity, and larger dynamic range.

The elaboration is the study is to examine the difference in the sound level in the air handling units made by the same producer. These units are of the same design parameters and components, and supply air and exhaust air. The only difference is mounted engines. Tested air handling units are equipped with an engine type EC, and traditional direct drive, controlled by an converter. Sound level measurements were carried out in the ducts supply air ventilation system at a distance of 1 m from the air handling unit and for the unit at a distance of 2 m from the inspection door of the fan section of the supply, with 3 settings efficiency of units 30%, 60% and 90%. Tested headquarters are located inside the building. Excessive noise has a negative effect on the human body, resulting in fatigue, difficulty in learning and concentration, impaired orientation, annoyance, increase in blood pressure, headaches, dizziness, and in the worst case of temporary or permanent hearing loss. For this reason it is very important to protect against noise. Therefore, it was these studies.

The hair cells in the cochlea are responsible for transforming sound-induced vibration into electrical signals. Damage to these hair cells is among the most common forms of hearing loss in the developed world. Researchers have studied various artificial hair cell (AHC) designs for replacing these hair cells. One such method uses piezoelectric beams to mimic the hair cell’s mechanoelectrical transduction. A piezoelectric beam will produce an electric potential from an applied sound pressure. In the literature, the response of the cochlea to sound pressures is often described using tuning curves. Tuning curves plot the sound pressure level at a given frequency which produces a particular displacement, velocity, or neuron firing rate. The work presented here examines using piezoelectric AHC’s to mimic cochlear hair cells by creating tuning curves of constant tip velocity and voltage. A piezoceramic (PZT) beam and a piezo film (PVDF) bending sensor are examined. An output feedback controller based on PID control is developed to vary the sound pressure from a speaker to create tuning curves for the piezoelectric AHC’s. The tuning curves for the piezoelectric beams are compared to measurements obtained from the biological cochlea.