Dissertations / Theses on the topic 'Audiometry - pure tone'

Pure tone hearing threshold measurement is the most basic and common test for diagnosis of hearing loss and for compensation of the loss with hearing instruments. Pure-tone hearing thresholds are usually assessed using a simple standardized method. By employing an optimal strategy, the thresholds can be determined with the same accuracy as the standard method with much less presentations. With prior knowledge extracted from the Beltone’s extra database, which contains over 400,000 audiograms including age and gender information, a more detailed prior knowledge will help improve the optimal strategy and efficiency of PTA process. Meanwhile, a graphical user interface is implementing the method with a more direct way to the users (doctors and patients), which makes the optimal process more accessible and easy to control.

Distortion-product emissions (DPEs) are tonal responses that may be detected in the ear canal when the ear is stimulated simultaneously by two tones that are closely spaced in frequency. In experimental animals, DPEs are reduced in amplitude or are eliminated when cochlear function is disrupted. This association has not been investigated in human subjects. This study was designed to investigate the relation of cochlear status, as determined by pure-tone behavioral thresholds, to DPE amplitude in human subjects. Forty men were selected as subjects. Twenty had normal hearing and 20 had high-frequency sensorineural hearing loss. Pure-tone behavioral thresholds were determined using conventional audiometric procedures for eight frequencies from 750 to 8000 Hz. DPEs were generated in the test ear of each subject by stimulating the ear with two tones, f1 and f2. The stimuli were selected to approximate audiometric test frequencies. Responses were detected by a sensitive microphone that was placed in the ear canal and were extracted by spectral analysis. Results of the study indicated that DPE amplitude was associated with pure-tone threshold. When audiometric threshold was ≤10 dB HL, DPEs could be elicited at all test frequencies for 98% of subjects in both groups. Mean maximum emission amplitude ranged from 3 to 13 dB SPL across frequency. When pure-tone threshold was above 50 dB HL, DPEs were absent or were significantly attenuated. DPEs varied in amplitude when audiometric threshold was between these two extremes. The association of DPE amplitude were pure-tone threshold was frequency specific. DPE amplitude was maximal when pure-tone thresholds were ≤10 dB HL and decreased as pure-tone behavioral threshold increased in the same subject. Repetition of the DPE protocol with five subjects from each group during separate test sessions indicated that the results were reliable over time. Results of the study have clinical implications. The technique may have potential as a noninvasive means of monitoring the status of the cochlea in human subjects.

Human hearing is to collect information from the outside world and is one of the basic human senses. Part of this thesis is devoted to acoustics, properties of the human ear in terms of perception of sounds and methods, which human ears are investigating. Audiometer is an instrument which is most often used in healthcare. The main content of this thesis is to design pure tone audiometer, which is important for the subjective tests of human hearing non-invasive method.

Previous studies show that pure tone thresholds are strongly correlated with distortion product otoacoustic emission amplitudes when evaluating the frequency range from 1 to 8 kHz (Avan & Bonfils, 1993). Little is known about correlations between these two measures at higher frequencies from 9-16 kHz. This study compared pure tone thresholds and distortion product otoacoustic emissions (DPOAEs) in this high frequency range for 29 normal hearing subjects ages 18-30. Pure tone thresholds were obtained at 250-16 kHz and distortion product otoacoustic emissions (DPOAE) 2,211-17,675 were measured in the same ears. DPOAE amplitudes were measured using a constant F1/F2 ratio of 1.2, with F2 values ranging from 2,211-17,675 Hz. Data obtained from 50 ears showed a decline in DPOAE amplitude with increasing frequency of the F1 and F2 primary stimulus tones. Behavioral thresholds demonstrated an increase with increasing frequency of the pure tone stimulus. Pearson r-correlation analysis demonstrated a weak relationship between measures. Further investigation revealed that equipment variables prevented accurate readings.

Introdução: Os motociclistas estão expostos tanto ao ruído ambiental como ao ruído gerado pela própria motocicleta. Tal exposição ao ruído pode provocar lesões na orelha interna, de modo que o registro das emissões otoacústicas por produto de distorção (EOAEPD) pode evidenciar as alterações de forma precoce. Objetivo: Verificar as variações das amplitudes das emissões otoacústicas evocadas por produto de distorção nos carteiros motociclistas normo-ouvintes de acordo com o tempo de exposição a ruído e analisar com trabalhadores normo-ouvintes não expostos a ruído ocupacional. Método: Foram avaliados 148 trabalhadores normo-ouvintes, distribuídos em quatro grupos: grupo I com exposição a ruído menor ou igual a dois anos, o grupo II com mais de dois anos e menos de cinco anos e o grupo III maior ou igual a cinco anos de exposição e o grupo IV não exposto ao ruído. Todos os trabalhadores selecionados foram submetidos ao registro das EOAEPD. Resultados: O grupo I apresentou amplitudes mais elevadas em 7250 Hz e 5128 Hz (p < 0,05), em comparação aos grupos II, III e IV. As menores respostas de amplitudes das EOAEPD ocorreram no grupo controle (grupo IV), sendo estatisticamente significativo nas freqüências entre 5128 Hz e 2588 Hz (p < 0,05). Conclusão: Os resultados sugerem que o monitoramento no início da exposição ao ruído ocupacional, por meio das emissões otoacústicas por produto de distorção, possibilita a detecção de alterações fisiopatológicas precoces da orelha interna por causa da presença de incrementos no registro da amplitude das EOAEPD. Estes incrementos precedem as alterações na audiometria tonal liminar e a ausência ou diminuição na amplitude das EOAEPD
Introduction: The motorcyclists are exposed as much to the environmental noise as to the noise generated by the own motorcycle. Such exposition to noise can provoke lesions in the internal ear and the registration of the distortion product otoacoustic emissions (DPOAEs) can evidence the alterations in a precocious way. Objective: To verify the variations of the amplitudes of the otoacoustic emissions evoked by distortion product in the postmen normo-listeners motorcyclists\' in agreement with the time of exposition to noise and to analyze with normo-listeners workers not exposed to occupational noise. Method: Hundred and forty-eight normo-listeners workers has been evaluated, distributed into four groups: group I - exposed to a smaller noise equivalent to two years noise-exposition; group II - equivalent to more than two years exposition and less than five years; group III - larger or equal to five years exposition; and the group IV - workers not exposed to noise being assigned to the control group. All selecioned workers were submitted to DPOAEs registration. Results: The group I presented higher amplitudes for 7250 Hz and 5128 Hz frequencies (p < 0.05), in comparison with the groups II, III and IV. The lowest values of DPOAEs amplitudes were observed in the control group (group IV), being statistically significantive for frequencies between 5128 Hz and 2588 Hz (p < 0.05). Conclusion: The results suggest that early monitoring of the exposition to occupational noise, through the distortion product otoacoustic emissions, makes possible the detection of precocious physiopathologic alterations of the internal ear due to the presence of increments in the amplitude registration of the DPOAEs. These increments precede the alterations in the preliminary tonal audiometry and the absence or decrease in the amplitude of the DPOAEs

This study assessed the effective use of pure-tone testing versus speech testing as used to predict the degree of hearing handicap experienced by an individual. Twenty-one subjects over the age of 65 were tested. Each subject was administered the following test battery: spondee threshold; a pure-tone evaluation, including air and bone conduction; Speech Perception in Noise (SPIN) test; Synthetic Sentence Identification (SSI) test; NU-6 for speech discrimination; establishment of most comfortable listening level (MCL) and loudness discomfort listening level (LDL); immittance testing including tympanograms, acoustic reflex thresholds, and reflex decay.

A student manual of audiological procedures with accompanying laboratory assignments does not presently exist at the University of South Florida (USF). In the first year of the four year Au.D. program at USF, students are enrolled in Audiology Laboratory Clinic I, II, and III, in consecutive semesters. Groups of four to six students meet weekly for a 3-1/2 hour clinical laboratory session to receive training in test instruction, test procedures, test application, and test interpretation. The purpose of the first year Audiology laboratory clinic sessions is to prepare the student for clinical experience in year two of the Au.D program at USF. In preparation for these laboratory sessions, it was discovered that materials related to test procedures are currently scattered throughout a variety of texts, journals, manuals, educational software, videos, and web sites. No one source contains all the needed information on any given test procedure. In addition, specific procedures outlined in documents [American Standards Institute (ANSI) and the American Speech-Language-Hearing Association (ASHA)] are not consistently used by the different sources. Thus, there is no standard procedural manual containing laboratory assignments that lead to the development of appropriate clinical testing skills by a first year Au.D student. A standard test procedural manual for pure tone audiometry, speech audiometry, and immittance testing, with assignments, was developed to assist in the cultivation of the students testing skills. The manual contains test history, purposes, procedures, scoring guidelines, interpretations, and limitations for each test. Laboratory assignments include practice exercises using a computer simulator, classmates, and volunteers. Each assignment is accompanied by discussion questions to enhance and augment student understanding. A reference list is available to obtain further information on each topic area. This manual will be made available to the first year Au.D student as well as to the advanced Au.D student who would benefit from an all-inclusive, updateable source providing the best possible clinical procedures. The final product will be available for a fee in a notebook type format to allow for the inclusion of additional topics and updates as the standards of practice in Audiology change.

At-risk hearing conditions in various aerobic classes in different gymnasiums were identified and the hearing of aerobic class goers monitored to provide information for an improved understanding of noise-induced hearing loss. Hearing levels were monitored over time for four comparison groups, including regular attendees of aerobic classes with an average noise level above 85 dBA (“High-Risk” group), regular attendees of aerobic classes with an average noise level below 85 dBA (“Low-Risk” group), non-gym goers attending one “High-Risk” aerobic class with hearing protection (“Control with HP” group), and non-gym goers attending one “High-Risk” aerobic class without hearing protection (“Control without HP” group). Each comparison group consisted of three to five males and three to five females, aged between 18 to 50 years. Measurements of pure-tone audiometry (PTA) and distortion product otoacoustic emissions (DPOAEs) were obtained from before and immediately after participation in one class and 48 hours and 30 days after the initial test. Noise levels in many aerobic classes (77%) were found to be higher than 85 dBA and might have led to signs of hearing deterioration as shown mostly in the reduction of the activities of outer hair cells and sometimes in the shift of hearing threshold. The “High-Risk” group exhibited the largest reduction of DPOAEs amplitudes over time. The “Control without HP” group generally exhibited a larger degree of reduction in DPOAEs amplitudes immediately after exposure as compared with the “Control with HP” group. Measurement of DPOAEs levels appeared to be a more sensitive tool than PTA in detecting early signs of hearing deterioration related to noise exposure.

Magister Public Health - MPH
Ototoxic induced hearing loss is a common adverse event related to aminoglycosides used in Multi Drug Resistant -Tuberculosis treatment. Exposure to ototoxic drugs damages the structures of the inner ear. Symptomatic hearing loss presents as tinnitus, decreased hearing, a blocked sensation, difficulty understanding speech, and perception of fluctuating hearing, dizziness and hyperacusis/recruitment. The World Health Organization (1995) indicated that most cases of ototoxic hearing loss globally could be attributed to treatment with aminoglycosides. The aim of the study was to determine the proportion of DR-TB patients initiated on treatment at three decentralized sites during a defined period (1st October to 31st December 2015) who developed ototoxic induced hearing loss and the corresponding risk factors, whilst receiving audiological monitoring with an extended high frequency audiometer (KUDUwave). A retrospective cross-sectional study was conducted. Cumulatively across the three decentralized sites, 69 patient records were reviewed that met the inclusion criteria of the study. The mean age of the patients was 36.1, with a standard deviation (SD) of 10.7 years; more than half (37) were female. Ototoxicity , a threshold shift, placing patients at risk of developing a hearing loss was detected in 56.5% (n=39)of patients and not detected in 30.4%(n=21).The remaining 13,1% (n=9)is missing data. As a result, the regimen was adjusted in 36.2% of patients. . From the 53 patients who were tested for hearing loss post completion of the injectable phase of treatment, 22.6% (n=12) had normal hearing, 17.0 % (n=9) had unilateral hearing loss, and 60.4% (n=32) had bilateral hearing loss. Therefore, a total of 41 patients had a degree of hearing loss: over 30% (n=22)had mild to moderate hearing loss, and only about 15% (n=11)had severe to profound hearing loss. Analysis of risk factors showed that having ototoxicity detected and not adjusting regimen significantly increases the risk of patients developing a hearing loss. The key findings of the study have shown that a significant proportion of DR-TB patients receiving an aminoglycoside based regimen are at risk of developing ototoxic induced hearing loss, despite receiving audiological monitoring with an extended high frequency audiometer that allows for early detection of ototoxicity (threshold shift).

Doctor Educationis
Ototoxic induced hearing loss is a common adverse event related to aminoglycosides used in Multi Drug Resistant -Tuberculosis treatment. Exposure to ototoxic drugs damages the structures of the inner ear. Symptomatic hearing loss presents as tinnitus, decreased hearing, a blocked sensation, difficulty understanding speech, and perception of fluctuating hearing, dizziness and hyperacusis/recruitment. The World Health Organization (1995) indicated that most cases of ototoxic hearing loss globally could be attributed to treatment with aminoglycosides. The aim of the study was to determine the proportion of DR-TB patients initiated on treatment at three decentralized sites during a defined period (1st October to 31st December 2015) who developed ototoxic induced hearing loss and the corresponding risk factors, whilst receiving audiological monitoring with an extended high frequency audiometer (KUDUwave). A retrospective cross-sectional study was conducted. Cumulatively across the three decentralized sites, 69 patient records were reviewed that met the inclusion criteria of the study. The mean age of the patients was 36.1, with a standard deviation (SD) of 10.7 years; more than half (37) were female. Ototoxicity , a threshold shift, placing patients at risk of developing a hearing loss was detected in 56.5% (n=39)of patients and not detected in 30.4%(n=21).The remaining 13,1% (n=9)is missing data. As a result, the regimen was adjusted in 36.2% of patients. . From the 53 patients who were tested for hearing loss post completion of the injectable phase of treatment, 22.6% (n=12) had normal hearing, 17.0 % (n=9) had unilateral hearing loss, and 60.4% (n=32) had bilateral hearing loss. Therefore, a total of 41 patients had a degree of hearing loss: over 30% (n=22)had mild to moderate hearing loss, and only about 15% (n=11)had severe to profound hearing loss. Analysis of risk factors showed that having ototoxicity detected and not adjusting regimen significantly increases the risk of patients developing a hearing loss. The key findings of the study have shown that a significant proportion of DR-TB patients receiving an aminoglycoside based regimen are at risk of developing ototoxic induced hearing loss, despite receiving audiological monitoring with an extended high frequency audiometer that allows for early detection of ototoxicity (threshold shift).

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INTRODUCTION: Many situations may difficult the obtaining of thresholds for each ear, separately, in pure tone audiometry, demanding the use of masking. The plateau method, developed by Hood (1960) has being the most utilized for more than four decades. Nevertheless, Turner (2004) has suggested a masking protocol with a different method, called optimized, which could replace the previous one with efficacy in specific cases. PURPOSE: To verify if there is a difference among air and bone conduction hearing thresholds, using the two clinical masking methods: plateau and optimized. METHOD: Forty individuals aged from 15 to 65 years old, with either unilateral or bilateral hearing losses, considering unilateral, bilateral, symmetrical and just bone, proposed by Turner s classification, have participated of this study. They underwent air and bone conduction pure tone audiometry for both ears, without and with the use of the two masking methods. RESULTS: There was a 6.1% difference between the results for the air conduction threshold retest and a 15.1 % for the bone conduction threshold retest, taking into consideration the symmetrical model and a 12.8% for the bone conduction retest, considering the just bone model. There was no statistically significant difference between the air and bone conduction hearing thresholds with the two masking methods, considering unilateral and bilateral models. CONCLUSION: The plateau method can be utilized for all models and the optimized one is the most efficient for unilateral and bilateral models, having no indication for the symmetrical model. Therefore, both masking methods have presented advantages and disadvantages, implying that the audiologist must have knowledge of them in order to choose correctly the masking method to be used
INTRODUÇÃO: Na realização da audiometria tonal, determinadas situações dificultam a obtenção dos limiares para cada orelha separadamente, havendo a necessidade de utilização do mascaramento. O Método Platô, desenvolvido por Hood (1960), vem sendo o mais utilizado há mais de quatro décadas. Contudo, em 2004, Turner sugeriu um protocolo de mascaramento no qual um diferente método, denominado Método Otimizado, poderia substituí-lo de forma eficaz em casos específicos. OBJETIVO: Verificar se há diferença entre os limiares auditivos obtidos, por via aérea e via óssea, utilizando-se dois métodos de mascaramento clínico: o Método Platô e o Otimizado. MÉTODO: Participaram deste estudo 40 indivíduos, com idades entre 15 e 65 anos, que apresentavam perda auditiva unilateral ou bilateral, considerando os modelos unilateral, bilateral, simétrico e somente-ósseo, propostos pela classificação de Turner (2004). Foram realizados os procedimentos de audiometria tonal liminar por via aérea e óssea, para ambas as orelhas, sem e com a utilização dos dois métodos de mascaramento. RESULTADOS: Não houve diferença estatisticamente significante entre os limiares auditivos obtidos com os dois métodos de mascaramento por via aérea e via óssea considerando-se os modelos, unilateral e bilateral. No entanto, houve diferença de 6,1% dos resultados para o re-teste dos limiares por via aérea e de 15,1% para o re-teste por via óssea, considerando o modelo simétrico e de 12,8% para o re-teste de via óssea, considerando o modelo somente-ósseo. CONCLUSÃO: O Método Platô pode ser utilizado para todos os modelos e o Otimizado é mais eficaz para os modelos unilateral e bilateral, não sendo indicado para o modelo simétrico. Diante disso, ambos os métodos de mascaramento apresentaram vantagens e desvantagens, sugerindo que o audiologista tenha conhecimento destas para que proceda a seleção do método de forma consciente

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
To estimate the measurement uncertainty of the pure-tone audiometry by air-conduction, in the frequencies from 250 Hz to 8000 Hz, and bone-conduction, at frequencies of 500 Hz to 4000 Hz. Method: This is an observational, descriptive and cross sectional study. Accuracy measurement tests under repeatability conditions were conducted (same measurement procedure, operator, measuring system, operating conditions and site, in a short time interval). Each of the nine participants took part in two trials with five repetitions each through air and bone conduction, in the right and left ear. In Trial 1 the interval between each repetition was five minutes. In Trial 2 the interval between repetitions was sixty minutes. To calculate the combined uncertainty the type A uncertainty, derived from repeatability, and Type B uncertainty derived from the audiometer calibration certificate, the audiometer resolution, and the conditions of the test environment were considered. Results: There was no statistically significant difference intra-individuals in different time intervals (p> 0,05), in both air and bone conduction. The median of type A uncertainty ranged from 0 dB to 2,7 dB in the right ear, and 0 dB to 3,5 dB in the left ear for air conduction. In bone conduction the median of type A uncertainty ranged from 2.2 dB to 2.7 dB in both ears. Type B uncertainties, for air and bone conduction, derived from the contribution of the equipment used for the test (0,4 dB), of the equipment resolution (1,4 dB), and the test environment (5,0 dB). Considering the median of type A uncertainty derived from accuracy measurement, and type B uncertainties mentioned above, the estimated of measurement uncertainty of pure tone audiometry, air and bone conduction, in this study, for the confidence level of 95% (k=1.96) and 95.45% (k=2.0) were 10 dB or 11 dB, for the frequencies tested, in both Trials 1 and Trial 2, in both ears. Conclusions: This study demonstrates the feasibility of accuracy measurement tests under repeatability conditions, as proposed in this work. In this study the contribution of type B uncertainties, derived from the audiometer calibration certificate, potentiometer and test environment, this latter being more prevalent, was higher than that of type A uncertainty derived from repeatability, indicating the need to keep control of these variables. The expression of measurement uncertainty can increase even more the sensitivity and specificity of audiometry, respectively increasing the rate of true positives and true negatives, since it is considered the gold standard. In this study the expanded uncertainty, for the confidence level of 95% and 95,45% ranged between 10 and 11 dB, in air and bone conduction. The reliability of the pure-tone audiometry test depends on the expression of its uncertainty; only so results obtained with the same subject in different places and times can be compared. Therefore the expression of uncertainty should be taken into consideration when delivering results and in preparing reports, for subsidizing decisions on hearing aids prescription, selection and adaptation procedures, as well as assessment of social security benefit payments, labor actions and health surveillance actions
Estimar a Incerteza de Medição no exame de audiometria tonal por via aérea, nas frequências de 250 Hz a 8 000 Hz, e por via óssea, nas frequências de 500 Hz a 4 000 Hz. Método: Nesta pesquisa, de natureza observacional, descritiva e transversal, foram realizados ensaios de precisão de medição sob condições de repetibilidade (mesmo procedimento de medição, operador, sistema de medição, condições de operação e mesmo local, em curto intervalo de tempo). Cada um dos nove participantes realizou dois ensaios, com cinco repetições de audiometria cada, por vias aérea e óssea, orelhas direita e esquerda. No Ensaio 1 o intervalo entre cada repetição foi de cinco minutos. No Ensaio 2 o intervalo entre as repetições foi de sessenta minutos. Para cálculo da incerteza padrão combinada considerou-se a incerteza do tipo A, derivada da repetibilidade, e as incertezas do tipo B, derivadas do certificado de calibração do audiômetro, da resolução do audiômetro, e das condições do ambiente de teste. Resultados: Para as vias aérea e óssea não houve diferença estatisticamente significante intraindivíduos nos diferentes intervalos de tempo (p > 0,05). A mediana da incerteza do tipo A variou de 0 dB a 2,7 dB, na orelha direita, e de 0 dB a 3,5 dB na orelha esquerda, para a via aérea. Na via óssea a mediana da incerteza do tipo A variou de 2,2 dB a 2,7 dB, em ambas as orelhas. As incertezas do tipo B, tanto para via aérea quanto para a via óssea, foram derivadas da contribuição do equipamento utilizado para o exame (0,4 dB), da resolução do equipamento (1,4 dB), e do ambiente de teste (5,0 dB). Levando-se em consideração a mediana das incertezas do tipo A e as incertezas do tipo B citadas acima, a estimativa da incerteza de medição da audiometria tonal por vias aérea e óssea, neste estudo, para os níveis da confiança de 95% (k=1,96) e 95,45% (k=2,0), foi de 10 dB ou 11 dB, nas frequências testadas, tanto no Ensaio 1 quanto no Ensaio 2, em ambas as orelhas. Conclusões: Este estudo demonstra a viabilidade de ensaios de precisão de medição sob condições de repetibilidade, conforme proposto neste trabalho. Neste estudo a contribuição das incertezas do tipo B, derivadas do certificado de calibração do audiômetro, do potenciômetro e do ambiente de teste, preponderando esta última, foi maior do que a incerteza do tipo A, derivada da repetibilidade, indicando a necessidade de manter-se controle sobre estas variáveis. A expressão da incerteza de medição da audiometria pode elevar, ainda mais, a sensibilidade, e a especificidade da audiometria, respectivamente aumentando a taxa de verdadeiros positivos e de verdadeiros negativos, uma vez que é considerada padrão ouro. Neste estudo a incerteza de medição expandida, para os níveis da confiança de 95% e 95,45% variou entre 10 dB e 11 dB, tanto para via aérea quanto para via óssea. A confiabilidade do exame de Audiometria Tonal, ou Audiometria de Tons Puros depende da expressão de sua incerteza; somente assim resultados obtidos com o mesmo sujeito, em locais e épocas diferentes, podem ser comparados. Portanto a expressão da incerteza deve ser levada em consideração quando da entrega de resultados e confecção de relatórios, seja para decisão sobre procedimentos de indicação, seleção e adaptação de aparelhos de amplificação sonora individual, assim como para avaliação de concessão de benefícios previdenciários, ações trabalhistas e ações de vigilância em saúde

The purpose of this study was to evaluate an updated list of digitally recorded Speech Recognition Threshold (SRT) materials for test-retest reliability. Chipman (2003) identified 33 psychometrically equated spondaic words that are frequently occurring in English today. These digitally recorded words were used to determine the SRT of 40 participants using the American Speech-Language Hearing Association guidelines. The participants were between the ages of 19 and 83 years and presented with hearing impairment ranging from normal to severe. The individual's pure-tone averages classified 16 participants with normal hearing to slight loss, 12 participants with mild loss, and 12 participants with moderate to severe hearing loss. The speech materials were presented to participants in one randomly selected ear. The SRT was measured for the same ear in both the test and retest conditions. The average SRT for the test condition was 22.7 dB HL and 22.8 dB HL in the retest condition with an improvement of 0.1 dB for retest but no significant difference was identified. Using a modified variance equation to determine test-retest reliability resulted in a 0.98, indicating almost perfect reliability. Therefore the test-retest reliability was determined to be exceptional for the new SRT words.

Occupational exposure-related hearing loss is a significant health concern for affected workers. Organic solvent exposure has emerged as an important contributor to hearing loss. It is thought that hearing loss related to solvent and noise exposure is mediated by reactive oxygen species (ROS). The glutathione associated enzymes and the manganese superoxide dismutase enzymes (SOD2) are important components of the cochlear hair cellâs defense against oxidative stress. This study is aimed to determine whether polymorphisms within the glutathione S-transferases (GST) P1 and GSTM1, glutathione peroxidase 1 (GPX1), and SOD2 are associated with hearing status in solvent exposed factory workers. Genotypes for the GSTM1 + vs. null, GSTP1 Ile105Val, GPX1 Pro198Leu, SOD2 Val16Ala polymorphisms along with hearing status were determined in factory workers exposed to organic solvents. Hearing tests consisted of pure tone audiometric (PTA) thresholds from 3-6 kHz and distortion product otoacoustic emissions (DPOAEs) for 3-6 kHz. Bivariate and multivariate regression analysis was undertaken to assess for association between polymorphisms and hearing outcomes. The GSTP1 Val/Ile genotype at position 105 was associated with higher PTA thresholds (β=12.41, P value= 0.01) from 3-6 kHz in workers below age 22-43. The analysis showed a protective association of the SOD2 Ala/Val genotype (β= -26.42, P value= 0.025) and The GPX1 Leu/Leu genotypes (β=47.81, P value= 0.034) with audiometric thresholds from 3-6 kHz in individuals above age 43. This small cross-sectional study suggests that polymorphisms within the antioxidant system may alter susceptibility to hearing loss in workers exposed to organic solvents. These results also suggest the mechanisms by which this affect are mediated are complex and should be further investigated.

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The aim of this study was to evaluate the hearing and the prevalence of hearing impairment among children, in the age groups of 3 to 6 years old, from Municipal Nursery and Pre-schools of São José do Rio Preto, S.P. At first stage, audiometries in a free field were performed for screening in 103 children, both sexes in 8 Nursery and 8 Pre-schools previously selected. At second stage, the ones who presented audiometric alterations were referred to the Phonoaudiological Service of FAMERP to perform conventional pure tone audiometer. The classification of hearing impairment in relation to grade was made according to W.H.O. approaches. A male child (0.97%) was found with light grade of conductive hearing impairment in the left ear ( LE=35 dB). There was no significant difference among the ratio of hearing impairment in both sexes (p=1.00). Nine children (8.73%) showed alterations in the hearing thresholds by air conduction in 4000, 6000 and/or 8000 Hz sharp frequencies. The ratio among alterations in these frequencies was not statistically significant in both sexes (p=1.00). There is need of further studies to evaluate the result found in children with alterations in those sharp frequencies. The found prevalence of hearing impairment in this studied population can chek the need of use of prevention programs and earlier diagnosis of hearing impairments.
Este estudo teve como objetivo realizar a avaliação da audição e o levantamento da prevalência de deficiência auditiva em amostra de crianças, na faixa etária de 3 a 6 anos, em creches e pré-escolas municipais de São José do Rio Preto, etapa, em 103 crianças de ambos os sexos, na referida faixa etária, em 8 creches e 8 pré-escolas previamente selecionadas. As crianças que apresentaram alterações audiométricas na triagem, foram encaminhadas ao ambulatório de fonoaudiologia da famerp para realização de audiometria tonal convencional, em uma segunda etapa. A classificação da deficiência auditiva, em relação ao grau, foi feita segundo os critérios da oms. Foi encontrado uma criança do sexo masculino (0,97%) com deficiência auditiva condutiva de grau leve na orelha esquerda (m oe=35 db). Não houve diferença significativa entre as proporções de deficiência auditiva em ambos os auditivas, por via aérea, nas freqüências agudas de 4000, 6000 e/ ou 8000 hz. Nota de Resumo Não foi estatisticamente significante a diferença entre as proporções de alterações nas freqüências acima descritas em ambos os sexos (p=1,00). Há necessidade de posteriores estudas para avaliação do resultado encontrado em relação ás crianças com alterações nas referidas freqüências agudas. A prevalênciaencontrada de deficiência auditiva na população do estudo, pode comprovar a necessidade da implantação de programas de prevenção e diagnóstico precoce da deficiência auditiva. Unitermos: surdez- métodos de avaliação, classificação; crianças- pré-escolares; audiometria-tonal, da fala.

It is estimated that 10% of the global population is impaired to a significant degree by a decrease in hearing sensitivity. With the greatest proportion of these persons residing in developing countries where communities are grossly underserved, it is incumbent on hearing healthcare professionals to seek means of offering equitable hearing health care services to these communities. The delivery of conventional diagnostic hearing services to these population groups is challenged by limitations in human resources, financial constraints and by the dearth of audiometric testing facilities that are compliant with permissible ambient noise levels for reliable testing. Valid diagnostic hearing assessment without an audiometric test booth will allow greater mobility of services and could extend hearing healthcare service delivery in underserved areas. The purpose of this study was to investigate the validity of diagnostic pure tone audiometry in a natural environment, outside a sound treated room, using a computer-operated audiometer with insert earphones covered by circumaural earcups incorporating real-time monitoring of environmental noise. A within-subject repeated measures research design was employed to assess elderly adults with diagnostic air (250 to 8000 Hz) and bone (250 to 4000 Hz) conduction pure tone audiometry. The study was of a quantitative nature and the required data was collected by testing subjects initially in a natural environment and subsequently in a sound booth environment to compare the threshold measurements. One experienced audiologist used audiometric KUDUwave test equipment to evaluate subjects in both environments. A total of 147 adults with an average age of 76 (± 5.7) years were tested. Ears had pure tone averages (500, 1000, 2000 and 4000 Hz) of ≥ 25 dB in 59%, >40 dB in 23% and ˃ 55 dB in 6% of cases. Analysis of collected data showed air conduction thresholds (n = 2259) corresponding within 0 to 5 dB in 95% of all comparisons between testing in the natural and sound booth environments. Bone conduction thresholds (n = 1669) corresponded within 0 to 5 dB in 86% of comparisons and within 10 dB or less in 97% of cases. Average threshold differences (–0.6 to 1.1) and standard deviations (3.3 to 5.9) were within typical test-retest reliability limits. Recorded thresholds showed no statistically significant differences with a paired samples t-test (p ˃ 0.01) except at 8000 Hz in the left ear. Overall the correlation between the air-conduction thresholds recorded in the sound booth environment and the natural environment was very high (˃ 0.92) across all frequencies while for bone conduction threshold correlation for the two environments fell between 0.63 and 0.97. This study demonstrates that valid diagnostic pure tone audiometry in an elderly population can be performed in a natural environment using an audiometer employing insert earphones covered by circumaural earcups with real-time monitoring of ambient noise levels. Mobile diagnostic audiometry performed outside of an audiometric sound booth may extend current hearing healthcare services to remote underserved communities where booths are scarce or inaccessible. In combination with Telehealth applications this technology could offer a powerful and viable alternate diagnostic service to persons unable to attend conventional testing facilities for whatever reasons.
Dissertation (MCommunication Pathology)--University of Pretoria, 2013.
gm2014
Speech-Language Pathology and Audiology
Unrestricted

碩士
國立台北護理學院
聽語障礙科學研究所
98
The purpose of this study is to obtain the behavioral thresholds in response to the click and tone bursts of 500, 1000, 2000 and 4000 Hz by using the Nicolet and the Integrity™ auditory evoked systems from a small group of normal-hearing subjects. The ABR thresholds were obtained with the click and tone bursts stimuli from subjects with normal hearing sensitivity. The ABR thresholds were compared with the pure tone thresholds, and the results of ABR thresholds from two auditory evoked systems were also compared. The averaged time to complete the ABR threshold test by using two auditory evoked systems was compared. All participants in this study exhibited pure tone thresholds of 10 dB HL or less at 500, 1000, 2000 and 4000 Hz. The reference level of each stimulus was determined based on the averaged behavioral thresholds of 15 subjects and was designated as 0 dB nHL for the specific stimulus. Single-channel recordings of the ABR were obtained from using cup electrodes placed at the vertex and mastoid ipsilateral to the stimulated ear. It was found that the mean differences between the ABR thresholds in response to click and the pure tone average of 2000 and 4000 Hz by using Nicolet and Integrity™ auditory evoked systems were 0.7 and 3.3 dB, respectively. The mean differences between the ABR thresholds and pure tone thresholds at 500, 1000, 2000 and 4000 Hz by using the Nicolet auditory evoked system were 11.7, 7.3, 4.0 and 4.3 dB, respectively. The mean differences between the ABR thresholds and pure tone thresholds at 500, 1000, 2000 and 4000 Hz by using the Integrity™ auditory evoked systems were 15.7, 8.7, 6.7 and 6.7 dB, respectively. No significant difference (p＞.01) was found between the ABR thresholds obtained by using the Nicolet and Integrity™ auditory evoked systems when the stimuli were the click and tone bursts of 1000, 2000 and 4000 Hz. The difference in ABR thresholds obtained by using the Nicolet and Integrity™ auditory evoked systems was significant (p＜.01) when using 500 Hz tone burst as stimulus. The averaged time to complete the ABR threshold test by using the Integrity™ auditory evoked system was shorter than that one by using the Nicolet auditory evoked system (p＜.01). In summary, the present study suggests that by using the Nicolet or Integrity™auditory evoked system, there is consistency between the ABR thresholds in response to the click and the pure tone average of 2000 and 4000 Hz. By using the ABR thresholds to tone bursts, reasonable estimates of 500, 1000, 2000 and 4000 Hz pure tone thresholds were comparable from Nicolet or Integrity™ auditory evoked systems in subjects with normal hearing sensitivity.

碩士
國立臺北護理健康大學
語言治療與聽力研究所
105
The purpose of this study is to compare threshold measures with auditory brainstem response (ABR) , auditory middle latency response (AMLR) to tone bursts of 500 and 4000 Hz, and pure tone audiometry. Seventeen participants aged from 25 to 60 years old, exhibited pure tone thresholds ranged from 40 to 80 dB HL at 500 and 4000 Hz, as well as type A tympanograms. The results indicated that the mean differences between ABR and pure tone thresholds of 500 and 4000 Hz were 6.0 and 6.3 dB respectively, standard deviations were 7.8 and 6.6 dB respectively. The mean differences of AMLR and pure tone thresholds of 500 and 4000 Hz were 3.6 and 2.3 dB respectively, standard deviations were 6.1 and 7.0 dB respectively; The mean differences of ABR and AMLR thresholds of 500 and 4000 Hz were 2.3 and 4.0 dB respectively, standard deviations were 5.9 and 6.8 dB respectively. Statistical analysis revealed that there was no significant difference (p > .05) among thresholds of pure tone, ABR and AMLR at 500 and 4000 Hz. The analysis among thresholds of pure tone, ABR and AMLR for 500 and 4000 Hz also exhibited high correlations (r > .80). In summary, the present study suggests that comparable results were found between tone bursts ABR and AMLR thresholds of 500 and 4000 Hz. A reasonable estimate to the pure tone thresholds in adults with hearing loss is feasible by using tone bursts ABR and AMLR.

Audiologists are reliant on objective audiometric procedures to predict auditory sensitivity in difficult-to-test populations. A technique to estimate frequency-specific hearing thresholds in a time-efficient way for difficult-to-test populations, who are unable to provide behavioural responses, has long been the hope of audiologists. The auditory brainstem response (ABR) has dominated the field of objective electrophysiological audiometry for the past three decades. Although it provides a useful method of estimating auditory sensitivity, it presents with its own set of limitations. Recently the auditory steady state response (ASSR) has demonstrated promise of addressing the limitations of the ABR as it is an evoked response uniquely suited to frequency-specific measurement. An optimised version of the ASSR, the dichotic multiple frequency (MF) ASSR, has been proposed as a time-efficient way of evaluating different frequencies simultaneously in both ears. The aim of this study was to evaluate the clinical usefulness of the dichotic MF ASSR technique for estimating pure tone behavioural thresholds at 0.5, 1, 2, and 4 kHz, compared to a 0.5 kHz tone burst and broadband click ABR protocol in a sample of normal hearing adults (56 ears). A comparative experimental research design was selected in order to compare thresholds obtained with the different procedures. The results indicated that both the dichotic MF ASSR and a 0.5 kHz tone burst and broadband click ABR protocol provided a reasonable estimation of PT behavioural thresholds in a time-efficient manner for a group of normal hearing subjects. The click ABR did, however, present with 1, 2, and 4 kHz PT threshold estimations that were almost 50 % closer than that of the dichotic MF ASSR according to the mean and normal deviation. This increased accuracy and reliability of the click ABR is however compromised by its lack of frequency-specificity. In the low frequency region of 0.5 kHz, the tone burst ABR and dichotic MF ASSR evidenced estimations of the pure tone threshold that were, on average, very similar. The tone burst ABR, however, presented with a mean threshold slightly (3 dB) closer to the pure tone threshold than the dichotic MF ASSR. The 0.5 kHz dichotic MF ASSR presented with a smaller range of normal deviation in the estimation of pure tone thresholds which suggested a more reliable measure than the 0.5 kHz tone burst ABR. The dichotic MF ASSR evaluation provided eight thresholds (4/ear) in 23 minutes on average compared to 25 minutes on average required by the ABR protocol to evaluate 4 thresholds (2/ear). This research concluded that the dichotic MF ASSR is useful for estimating frequency-specific pure tone thresholds reasonably well in a time-efficient manner but that this technique should be used in a test-battery alongside the ABR. Both the dichotic MF ASSR and the ABR comprise unique qualities that can be combined in a cross-check principle approach in order to provide complementary information that will verify results obtained with each procedure.
Dissertation (MA (Communication Pathology))--University of Pretoria, 2006.
Speech-Language Pathology and Audiology
Unrestricted

In the evaluation of special populations, such as neonates, infants and malingerers, audiologists have to rely heavily on objective measurements to assess hearing ability. Current objective audiological procedures such as tympanometry, the acoustic reflex, auditory brainstem response and transient evoked otoacoustic emissions, however, have certain limitations, contributing to the need of an objective, non-invasive, rapid, economic test of hearing that evaluate hearing ability in a wide range of frequencies. The purpose of this study was to investigate distortion product otoacoustic emissions (DPOAEs) as an objective test of hearing. The main aim was to improve prediction of pure tone thresholds at 500 Hz, 1000 Hz, 2000 Hz and 4000 Hz with DPOAEs and artificial neural networks (ANNs) in normal and hearing-impaired ears. Other studies that attempted to predict hearing ability with DPOAEs and conventional statistical methods were only able to distinguish between normal and impaired hearing. Back propagation neural networks were trained with the pattern of all present and absent DPOAE responses of 11 DPOAE frequencies of eight DP Grams and pure tone thresholds at 500 Hz, 1000 Hz, 2000 Hz and 4000 Hz. The neural network used the learned correlation between these two data sets to predict hearing ability at 500 Hz, 1000 Hz, 2000 Hz and 4000 Hz. Hearing ability was not predicted as a decibel value, but into one of several categories spanning 1 OdB. Results for prediction accuracy of normal hearing improved from 92% to 94% at 500 Hz, 87% to 88% at 1000 Hz, 84% to 88% at 2000 Hz and 91% to 93% at 4000 Hz from the De Waal (1998) study to the present study. The improvement of prediction of normal hearing can be attributed to extensive experimentation with neural network topology and manipulation of input data to present information to the network optimally. The prediction of hearing-impaired categories was less satisfactory, due to insufficient data for the ANNs to train on. A prediction versus ear count correlation strongly suggested that the inaccurate predictions of hearing-impaired categories is not a result of an inability of DPOAEs to predict pure tone thresholds in hearing impaired ears, but a result of insufficient data for the neural network to train on. This research concluded that DPOAEs and ANNs can be used to accurately predict hearing ability within 10dB in normal and hearing-impaired ears from 500 Hz to 4000 Hz for hearing losses of up to 65dB HL.
Thesis (DPhil (Communication Pathology))--University of Pretoria, 2007.
Speech-Language Pathology and Audiology
unrestricted

KwaZulu-Natal has been ranked as having the fourth highest incidence of transmitted Multiple Drug Resistant-Tuberculosis (MDR-TB) in sub-Saharan Africa. Substantial literature exists indicating the permanent damage that MDR-TB medication has on hearing abilities. The purpose of this study was to describe the hearing function of adults on long term MDR-TB treatment from Murchison Hospital MDR-TB unit in the Ugu District in rural KwaZulu-Natal. The primary aim of the study was to review the possible changes in hearing function in a group of adults on long-term treatment for MDR-TB. Secondly, the study aimed to estimate the number of adults who may present with changes following MDR-TB treatment and establish if relationships exist between the audiological findings and factors such as age and gender. The design of the study was a retrospective comparative data review of 68 patient records, all of which underwent audiological investigations from the start of MDR-TB treatment over a five-month period. The study made use of descriptive and inferential statistics to analyse the data. Specific inferential statistical analysis included analysis of covariance as well as regression analysis. Results from the study showed changes in hearing function in Distortion Product Otoacoustic Emissions (DPOAEs) and Pure Tone Audiometry (PTA) results at all five audiological sessions and across a range of frequencies. 84% of the total sample presented with overall refer readings for DPOAEs and 98.53% of the group of adults presented with criteria indicative of ototoxic hearing loss, specifically a bilateral mild-profound sloping SNHL on clinical PTA results. In the total sample of patient records reviewed in this study, all 68 records showed a change in hearing function, be that changes in DPOAE function and/or changes in PTA thresholds, following long-term treatment for MDR-TB. Variations in the effects of gender and ear difference were minimal and non-significant in all results. Similar presentation, to ototoxic hearing loss, of other degenerative conditions exists; however these conditions were accounted for as exclusion criteria in this study. Therefore the only remaining cause of possible hearing deficit was that of ototoxicity. The study provided valuable data regarding hearing function in a population of adults on long-term MDR-TB treatment in South Africa. Furthermore, the study has highlighted the need for the establishment of standardised audiological monitoring programmes sensitive to ototoxic hearing loss, within the South African context where the incidence of Tuberculosis (TB) and MDR-TB is reportedly high.

Preliminary studies have stirred the hope that sound-field stimulation through auditory steady state evoked potentials can be used to assess aided thresholds in the difficult-to-test population. Before the introduction of ASSEP into the clinical field, as a technique for the prediction of aided thresholds in the difficult-to-test population, a question arises concerning its clinical validation. The application of ASSEP through sound field stimulation, in the determination of aided thresholds and for the evaluation of amplification fittings, is dependent on the determination of unaided responses. Subsequently the estimation of unaided thresholds in the hearing impaired population is dependent on the establishment of normative data from the normal hearing population. The aim of this study was to determine the influence of insert earphones and sound field speaker presentation on threshold estimations using monotic auditory steady state evoked potentials, in a group of normal hearing adults. To achieve the aim of the study, a comparative, within-group experimental design was selected. The results of the current study indicated that the monotic single ASSEP technique under both insert earphone- and sound field conditions provided a reasonable estimation (25-35 dB HL for inset earphones; 20-33 dB HL for sound field speaker presentation) of the behavioural pure tone thresholds. The minimum response levels obtained under insert earphone conditions differed significantly from those obtained under sound field conditions for all the frequencies tested except 2 kHz (p < 0.01). Subsequently, the current study indicates that minimum response levels obtained using a specific transducer should serve as the basis of comparison with behavioural thresholds obtained under the same transducer. Therefore, behavioural pure tone thresholds obtained under insert earphone conditions will not suffice as a basis of comparison for minimum response levels obtained for the ASSEP technique under sound field conditions, and vice versa. This research endeavour concluded that the monotic ASSEP technique under both insert earphone and sound field conditions provide useful information for the estimation of frequency specific thresholds, but that the results are transducer specific and that comparison across transducers should be avoided.
Dissertation (M (Communication Pathology))--University of Pretoria, 2006.
Speech-Language Pathology and Audiology
Unrestricted

The study investigated the feasibility of including DPOAEs in the annual medical surveillance test battery for the identification of NIHL in a group of employees in a manufacturing industry in KwaZulu-Natal. Feasibility was investigated by exploring the sensitivity, specificity and predictive efficiency of DPOAEs, the ability of DPOAEs to detect subtle noise-induced cochlea changes, the test-retest reliability of DPOAEs and lastly, the duration of time taken to conduct the DPOAE test bilaterally. A cross-sectional and repeated measures within-in participant design was utilized in the study. A purposive convenience sampling technique was used, as well as a stratified sampling approach in order to realize objective two of the study. The study consisted of 60 participants, which were further stratified into four test groups, i.e. Group A: 0-3 years, Group B: 3.1-6 years and Group C: 6.1-9 years and Group D: 9.1-13 years of working within the beverage manufacturing industry. A high sensitivity and negative predictive value was reported in the current study, suggesting that DPOAEs may be able to identify those who present with subtle cochlea changes as a result of exposure to occupational noise. The sensitivity of DPOAEs was 100% at 1, 2, 4, 6 and 8kHz in the right ear and at 4 and 6kHz in the left ear. The specificity of DPOAEs in the current study ranged between 55%-97% across the frequency range in the right ear and 49%-88% in the left ear. A negative predictive value of 100% was obtained bilaterally across the frequency range, except at 8kHz in the left ear. Visual inspection of the DPgram in the current study revealed a bilateral reduction in DPOAE amplitudes for all test groups in the high frequency region of the DP-Gram, namely, 5477Hz and 7303Hz, in the absence of a statistically significant difference (p>0.05). A greater frequency range appears to be affected in this group of workers, indicating that the type of noise, namely, impulse noise, may result in cochlea changes. Corresponding changes on the pure tone audiogram were not observed, however, noise notch configurations were observed for the groups with a longer history of noise exposure. This was not seen bilaterally as is typically expected with NIHL. Good test-retest reliability across the frequency range obtained in the current study further indicates the feasibility of including DPOAEs in the annual medical surveillance test battery. Additionally, the current study calculated an average of 86 seconds (1 minute 26 seconds) to conduct the DPOAE test bilaterally, confirming that DPOAEs are a quick test to administer. The findings of this study suggest that DPOAEs may be used to monitor early subtle noise-induced cochlea changes for workers exposed to noise in the beverage manufacturing industry as part of the annual medical surveillance test battery.
Thesis (M.Comm.Path.)-University of KwaZulu-Natal, Westville, 2013.

碩士
國立陽明大學
復健科技輔具研究所
91
Abstract The task of early detection of hearing problems for young children has been evoked continually in Taiwan. It is very important to find those young children with slight hearing loss and help them for better care. Basically, present methods of audiological test include otoacoustic emissions test, tympanogram and pure tone audiometry. The main purpose of applying the pure tone audiometry is for two reasons: lowering transfer rate and better detection precision to slight hearing loss. The researcher has conducted field observation and interviewing audiologists. Basically, the young children were less cooperating with the present procedure of pure tone audiometry, which has forced the audiometry operators providing other play activities such as toys and visual reinforcement audiometry. Thus, the procedure and related instrument of pure tone audiometry may need to be probed. This research has redesigned the procedure for audiological detection, which includes building multi-media audiological scenarios, and redesigning the audiometry technological assistive device. This research has probed not only the theoretical and clinical methods and procedures of audiometry, but also the needs and preferences for young children The result of this research has developed new audiometry instrument with innovative interactive user interface and play scenarios of hearing detection, such as fishing and slapping mosquitoes. The detection precision is normal above 20 db, and less precise under this threshold. The feedback from the young children is fun and much better cooperation. Moreover, this research has provided a new audiological assistive device with multi-media information technology, which may be continued further by developing more categories of the hearing detection scenario. Eventually, this research may improve the efficiency of pure tone audiometry.

RESUMO: Introdução e objetivos: Os testes de cabeceira podem diminuir o tempo de resposta clínica, melhorar a tomada de decisões e permitir uma rápida avaliação qualitativa da perda auditiva. Este estudo descreve o desenho e a validação dum novo teste de cabeceira com diapasão que permite quantificar a perda auditiva, na presença de surdez de condução unilateral. O estudo considerou três fases distintas: a primeira fase avaliou os efeitos da oclusão completa do canal auditivo externo sobre a audição, a fim de decidir qual a frequência de diapasão mais adequada para quantificar a hipoacusia com o teste de oclusão contralateral (TOC). A reprodutibilidade do método de oclusão entre examinadores também foi estudada nesta fase. A segunda fase avaliou o efeito da oclusão nos limiares auditivos de acordo com a idade, em indivíduos de idades distintas, para apurar qual o diapasão mais adequado na realização do TOC. A terceira fase avaliou a precisão do teste na previsão do grau de perda auditiva. Métodos: Nas três fases distintas do estudo consideraram-se populações com idade e tamanho da amostra diferentes. Na primeira fase do estudo, 20 adultos (40 ouvidos) com audição normal (21-30 anos de idade) foram submetidos a uma audiometria tonal em campo livre, com e sem oclusão do canal auditivo externo. Cada ouvido foi testado com as frequências standard (250, 500, 1000, e 2000 Hz) em tons de warble. O ouvido contralateral foi suprimido por mascaramento. A oclusão do ouvido foi realizada independentemente por 2 examinadores. Na segunda fase, 42 adultos (84 ouvidos) com audição normal (21-67 anos de idade) foram divididos em três grupos etários: 20-30, 40- 50, e 60-70 anos. Os participantes foram avaliados por audiometria tonal em campo livre, nas mesmas condições descritas para a primeira fase do estudo. Na terceira fase, 53 indivíduos com surdez de condução unilateral foram recrutados num departamento de otorrinolaringologia dum hospital terciário. O TOC foi realizado para determinar a lateralização com diapasões de 128 Hz, 256 Hz, 512 Hz, 1024 Hz e 2048 Hz e com a oclusão total do ouvido não afetado. A audiometria tonal foi então realizada, separadamente e cega em relação aos resultados do TOC, para determinar o gap aéreoósseo (ABG) e a o limiar auditivo médio (PTA). Por fim, as respostas do TOC foram comparadas com o ABG e o PTA para determinar a sua precisão na quantificação do grau da perda auditiva. Resultados: Na primeira fase do estudo, a oclusão do canal auditivo externo determinou uma elevação nos limiares auditivos com o aumento da frequência, desde 19.94 dB (250 Hz) até 39.25 dB (2000 Hz). A diferença dos limiares entre as condições de oclusão e não oclusão foi estatisticamente significativa, tendo aumentado de 10.69 dB (250 Hz) a 32.12 dB (2000 Hz). Não se verificaram diferenças estatisticamente significativas em relação ao género, ou entre examinadores. Na segunda fase do estudo, verificou-se uma elevação dos limiares auditivos com o aumento da frequência, de 20.85 dB (250 Hz, grupo 20–30 anos) a 48 dB (2000 Hz, grupo 60–70 anos). A diferença nos limiares auditivos entre as condições de oclusão e de não-oclusão foi estatisticamente significativa em todas as frequências; e aumentou de forma diretamente proporcional com a frequência, de 11.1 dB (250 Hz, grupo 20–30 anos) a 32 dB (2000 Hz, grupo 20–30 anos). Foram encontradas diferenças estatisticamente significativas para os três grupos etários, em todos os parâmetros, exceto na diferença a 500 Hz e na diferença total média. A perda auditiva média resultante da oclusão aos 500 Hz foi de 19 dB. Não se encontraram diferenças estatisticamente significativas entre o ouvido direito e o esquerdo, e entre géneros. Na terceira fase do estudo o TOC mostrou uma forte associação entre surdez e lateralização utilizando o diapasão de 512 Hz (p = .001). A sensibilidade do diapasão de 512 Hz na deteção de um PTA igual ou maior do que 35.6 dB foi de 94.6% e a especificidade foi de 75% para um valor preditivo positivo de 89.7% e um valor preditivo negativo de 85.7%, assumindo uma prevalência pré-teste de 69.8%. Conclusão: O método de oclusão do canal auditivo externo utilizado demonstrou reprodutibilidade entre examinadores e com a idade. A oclusão elevou os limiares auditivos, sendo este efeito mais evidente nas frequências mais elevadas. O TOC permitiu predizer o grau de hipoacusia de condução unilateral. Se ocorrer lateralização para a ouvido afetado, é quase certa a evidência de hipoacusia de condução moderada ou grave. No TOC podem utilizar-se diapasões de 256 ou 512 Hz para o diagnóstico de hipoacusia ligeira, e o diapasão de 2018 Hz para a hipoacusia moderada. Contudo, no estudo do efeito da idade e com a validação do teste foi possível concluir que a utilização do diapasão de 512 Hz é a mais adequada para o TOC. A utilização deste teste pode permitir aos clínicos, em ambiente de consulta e de forma rápida, a distinção entre uma hipoacusia de condução de grau ligeiro e uma hipoacusia de condução de grau moderado ou superior.
ABSTRACT: Introduction and goals: Bedside testing may accelerate clinical decision by making a quick qualitative assessment of hearing loss. This study described the design and validation of a bedside test with tuning forks that allow some quantitative evaluation of hearing loss in the presence of unilateral conductive hearing loss. Three distinct phases were considered: the first phase of the study quantified the effects of complete external auditory canal occlusion on hearing, in order to decide which tuning fork frequency is more appropriate to use for quantifying the hearing loss with the novel contralateral occlusion test (COT). The reproducibility of occlusion between examiners was also explored in this phase of the study. The second phase of the study evaluated the effects of external auditory canal occlusion on hearing thresholds with aging, in order to decide which tuning fork is more appropriate to use for the COT in individuals of different ages. The third phase of this study evaluated the accuracy of the test in predicting the degree of hearing loss. Methods: Over the study period, the three distinct phases considered population numbers of different age/size classes. At the first phase, 20 normal-hearing adults (40 ears) between 21-30 years old underwent sound field pure tone audiometry with and without ear canal occlusion. Each ear was tested with the standard frequencies (250, 500, 1000, and 2000 Hz) with warble tones. The contralateral ear was suppressed with the use of masking. Ear occlusion was performed by two examiners. In the second phase, 42 normal hearing subjects (84 ears) between 21 and 67 years were divided into three age groups (20–30 years, 40–50 years, and 60–70 years). Participants underwent sound field audiometry tests as described to the first phase of the study. In the third phase, 53 subjects with unilateral conductive hearing loss were recruited from an otolaryngology department of a tertiary hospital. The COT was performed to determine lateralization using 128, 256, 512, 1024 and 2048 Hz tuning forks with the non-affected ear meatus totally occluded. Pure-tone audiometry was then performed, separately and blinded of the tuning fork test results, to establish the presence and degree of the air-bone gap (ABG) and the pure-tone average (PTA). The tuning fork responses were finally correlated with the ABG and the PTA to determine their accuracy in quantifying the degree of hearing loss. Results: In the first phase of the study, occlusion of the external auditory canal determined an increase in hearing thresholds with increasing frequencies, from 19.94 dB (250 Hz) to 39.25 dB (2000 Hz). The difference on hearing thresholds between occluded and unoccluded conditions was statistically significant and increased from 10.69 dB (250 Hz) to 32.12 dB (2000 Hz). There were no statistically significant differences according to gender or between examiners. The second phase of the study demonstrated that hearing thresholds increased with higher frequencies from 20.85 dB (250 Hz, 20–30 years group) to 48 dB (2000 Hz, 60–70 years group). The difference on hearing thresholds between occluded and unoccluded conditions were statistically significant and increased, ranging from 11.1 dB (250 Hz, 20–30 years group) to 32 dB (2000 Hz, 20–30 years group). Statistically significant differences were found for the three age groups and for all evaluations except to 500 Hz difference and average difference. The mean hearing loss produced by occlusion at 500 Hz was approximately 19 dB. No statistically significant differences were found between right and left ears and gender for all measurements. In the third phase of the study COT showed a stronger association between hearing loss and the lateralization response using the 512 Hz tuning fork (p = 0.001). The sensitivity of the 512 Hz fork in detecting a PTA equal or greater than 35.6 dB was 94.6% and the specificity was 75.0% for a positive predictive value of 89.7% and a negative predictive value of 85.7%, assuming a pretest prevalence of 69.8%.Conclusions: The occlusion method as performed demonstrated reproducibility between examiners and with aging. The occlusion effect increased the hearing thresholds and became more evident with higher frequencies. The COT was accurate in predicting the degree of unilateral conductive hearing loss. If lateralization to the affected ear occurred, it was almost certain that the affected ear has a moderate or severe conductive hearing loss. 256 Hz or 512 Hz tuning forks were the more appropriate for diagnosis of mild hearing loss, and the 2048 Hz tuning fork was the more appropriate for moderate hearing loss; but aging and accuracy studies demonstrated that the use of the 512 Hz tuning fork is the most suitable for COT. The use of this test may allow clinicians to distinguish mild from moderate or greater than moderate unilateral conductive hearing loss.