Diss. (sammanfattning) Stockholm : Karolinska institutet, 2006. / Härtill 4 uppsatser.

Click-evoked otoacoustic emission (CEOAE) input/output (I/O) functions were measured in ears with normal hearing and in ears with sensorineural hearing loss above 2000 Hz. The low- to midfrequency CEOAEs obtained from the ears with high-frequency hearing loss were significantly reduced in level compared to the CEOAEs obtained from the ears with normal hearing even though there were no significant group differences in the 250-2000 Hz pure-tone thresholds. The findings are discussed within the context of two hypotheses that explain the low- to midfrequency reduction in transient-evoked otoacoustic emission (TEOAE) magnitude: (1) subclinical damage to the more apical regions of the cochlea not detected by behavioral audiometry, or (2) trauma to the basal region of the cochlea that affects the generation of low-frequency emissions. It is proposed that localized damage at basal cochlear sites affects the generation of low- to midfrequency CEOAE energy.

INTRODUÇÃO: Na deficiência auditiva não sindrômica de herança autossômica recessiva, causada por alteração no gene GJB2 (Gap Junction Bet-2 Protein), os pais de indivíduos com deficiência auditiva são portadores em heterozigose de um alelo recessivo que causa a surdez, porém, são assintomáticos, mas podem apresentar alterações auditivas precoces e discretas. OBJETIVO: Avaliar a função coclear em pais de indivíduos com deficiência auditiva de herança autossômica recessiva por meio das Emissões Otoacústicas Evocadas Produto de Distorção (EOA-PD) em frequências convencionais e em frequências ultra-altas, comparando as respostas do grupo controle pareadas por gênero e idade. MÉTODO: Foram avaliados 56 indivíduos, entre 20 a 58 anos de idade, divididos em dois grupos, o Grupo Estudo (GE), constituído por 28 pais de deficientes auditivos decorrentes de herança autossômica recessiva, sendo 14 mulheres com idade entre 20 a 55 anos (média 32,8 anos) e 14 homens com idade entre 20 a 58 anos (média 35,2), e o Grupo Controle (GC). formado por indivíduos sem queixa auditiva, composto por 14 homens e 14 mulheres com idades pareadas ao GE. Os indivíduos foram submetidos aos exames de Audiometria Tonal Liminar (ATL), Imitanciometria, incluindo a timpanometria e Reflexo Acústico (RA), e EOA-PD em frequências convencionais e em frequências ultra-altas. RESULTADOS: Não houve diferença estatisticamente significante entre as orelhas e grupos nos achados da ATL e RA, porém, nas respostas de EOA-PD, o GE apresentou diferença estatisticamente significativa em todas as frequências em comparação ao GC. A Correlação de Pearson entre a ATL e as EOA-PD, entre as orelhas e entre os grupos, mostrou correlação negativa entre as orelhas e grupos, indicando que, com o aumento no nível de resposta das EOA-PD, ocorre melhora nos limiares auditivos. A correlação de Pearson entre os resultados dos RA e as EOA-PD não demonstrou correlação significativa para ambos os grupos avaliados. A correlação de Pearson entre a idade e as EOA-PD, em frequências convencionais, mostrou correlação negativa significativa em algumas frequências, entretanto, não houve correlação entre a idade e as EOA-PD em frequências ultra-altas. Foi utilizado o intervalo de referência, diagramas de dispersão e análise discriminante para investigar-se se houve diferença entre as EOA-PD em frequências convencionais e em frequências ultra-altas, sendo que as EOA-PD em frequências convencionais mensuraram com maior precisão os sujeitos do GE, em relação às frequências ultra-altas. CONCLUSÃO: As EOA-PD, tanto para as frequências convencionais, quanto para as frequências ultra-altas, foram capazes de distinguir os indivíduos do GE e do GC, sugerindo que indivíduos heterozigotos para a mutação do gene GJB2 podem apresentar dano no processo ativo das células ciliadas externas antes da manifestação clínica por meio dos resultados alterados na avaliação audiológica convencional. / INTRODUCTION: In nonsyndromic hearing loss of recessive autosomal heritage, caused by changes in the gene GJB2 (Gap Junction Bet-2 Protein), parents of individuals with hearing loss are heterozygous carriers of a recessive allele which causes deafness, however, are asymptomatic, but may present early and mild hearing changes. OBJECTIVE: Assessing the cochlear function in parents of individuals with hearing loss of recessive autosomal heritage through Distortion Product Otoacoustic Emissions (DPOAE) in conventional frequencies and in ultra-high frequencies, comparing the responses of the control group paired by gender and age. METHOD: 56 individuals were assessed, aged between 20 and 58 years old, divided into two groups, the Study Group (GE), composed of 28 parents of hearing impaired people due to recessive autosomal heritage, 14 women being 20 to 55 years old (32.8 years old average) and 14 men being 20 to 58 years (35.2 years old average), and the Control Group (GC) formed by individuals without hearing complaints, composed of 14 men and 14 women being paired according to the age of GE. The individuals underwent examinations of Pure Tone Audiometry (PTA), Immittanciometry, including tympanometry and Acoustic Reflex (AR), and DPOAE in conventional frequencies and ultra-high frequencies. RESULTS: There was no statistically significant difference between the ears and the groups in the findings of PTA and AR; however, in the responses of DPOAE, the GE presented a statistically significant difference in all the frequencies compared to the GC. The Pearson Correlation between PTA and DPOAE, between the ears and between the groups, showed a negative correlation between the ears and the groups, indicating that, with the increase in the level of response of DPOAE, there is improvement in hearing thresholds. The Pearson Correlation between the results of AR and DPOAE showed no significant correlation for both groups assessed. The Pearson Correlation between age and DPOAE, in conventional frequencies, showed a significant negative correlation in some frequencies, however, there was no correlation between age and DPOAE in ultra-high frequencies. Reference range, scatter plots and discriminant analysis were used to investigate whether there was a difference between DPOAE in conventional frequencies and in ultra-high frequencies, given that DPOAE in conventional frequencies measured with greater precision the individuals from GE, in relation to the ultra-high frequencies. CONCLUSION: DPOAE, both for conventional frequencies and ultra-high frequencies, were able to distinguish individuals from GE and GC, suggesting that heterozygous individuals for the mutation of GJB2 gene may present damage in the active process of external ciliated cells before the clinical manifestation via altered results in the conventional hearing-aid assessment.

No description available.

It has been suggested that the presence of a limited area of damaged outer hair cells (OHCs) with intact inner hair cells, which may not be detected on the conventional audiogram, results in unbalanced neural activity between Type I and Type II fibers leading to tinnitus. In normal-hearing tinnitus patients, DPOAEs provided ambiguous data of OHC function when compared to non-tinnitus controls. Hearing loss in the extended high-frequency (EHF) region may decrease DPOAEs evoked at lower frequencies. Results of EHF audiometry in tinnitus patients are limited. The aim of the study was to evaluate DPOAEs and EHF thresholds in normal-hearing patients reporting unilateral tinnitus in left ear. Thus, each subject acted as their own control. Data were obtained for 26 subjects with bilateral hearing thresholds10, 12.5, 14, and 16 kHz. The DP-grams were measured in the 0.5-8 kHz range using 65/55-dB SPL primaries and f2/f1=1.2. The data analyses included DPOAEs with S/N>3 dB. Median audiometric data showed that thresholds in the left ears were significantly higher than those in the right ears at all four EHFs. Mean DPOAE levels of the left ears were lower than those of the right ears in the frequency range above 1 kHz. Additionally, a paired-comparison test of DPOAE levels of each patient’s right and left ear revealed significant differences at 6 and 8 kHz. The results indicate that: 1. OHC impairment in the most basal region reduces contribution to more apically generated DPOAEs; 2. OHC impairment in a limited area, which may be revealed by DPOAEs but not by conventional audiometry, can contribute to tinnitus generation; and 3. patients with unilateral tinnitus and normal hearing on the conventional audiogram are likely to demonstrate hearing loss in the EHF region.

No description available.

Past studies have shown that the effects of selective auditory attention are evident in medial olivocochlear (MOC) activity, manifested as the contralateral suppression (CS) of transient evoked otoacoustic emissions (TEOAEs). This finding suggests the use of TEOAEs in the design of an auditory-based access technology as a potential access solution for children with severe disabilities. Thirteen participants with normal hearing threshold and normal middle ear function completed this study. The participants were instrumented with a TEOAE ear probe and presented with a contralateral acoustic stimulus. They were instructed to alternate auditory attention conditions as visually cued by symbols on an LCD display. Attentive and non-attentive conditions were detected with an overall accuracy of 70.17 +/- 12.54% at 2.44 +/- 0.3 bits per minute in a participant-specific classifier, and 65.92 +/- 13.91% in a participant-independent classifier. Detection of auditory attention exceeded random chance levels for 11 of 13 participants.

Past studies have shown that the effects of selective auditory attention are evident in medial olivocochlear (MOC) activity, manifested as the contralateral suppression (CS) of transient evoked otoacoustic emissions (TEOAEs). This finding suggests the use of TEOAEs in the design of an auditory-based access technology as a potential access solution for children with severe disabilities. Thirteen participants with normal hearing threshold and normal middle ear function completed this study. The participants were instrumented with a TEOAE ear probe and presented with a contralateral acoustic stimulus. They were instructed to alternate auditory attention conditions as visually cued by symbols on an LCD display. Attentive and non-attentive conditions were detected with an overall accuracy of 70.17 +/- 12.54% at 2.44 +/- 0.3 bits per minute in a participant-specific classifier, and 65.92 +/- 13.91% in a participant-independent classifier. Detection of auditory attention exceeded random chance levels for 11 of 13 participants.

INTRODUÇÃO: Na deficiência auditiva não sindrômica de herança autossômica recessiva, causada por alteração no gene GJB2 (Gap Junction Bet-2 Protein), os pais de indivíduos com deficiência auditiva são portadores em heterozigose de um alelo recessivo que causa a surdez, porém, são assintomáticos, mas podem apresentar alterações auditivas precoces e discretas. OBJETIVO: Avaliar a função coclear em pais de indivíduos com deficiência auditiva de herança autossômica recessiva por meio das Emissões Otoacústicas Evocadas Produto de Distorção (EOA-PD) em frequências convencionais e em frequências ultra-altas, comparando as respostas do grupo controle pareadas por gênero e idade. MÉTODO: Foram avaliados 56 indivíduos, entre 20 a 58 anos de idade, divididos em dois grupos, o Grupo Estudo (GE), constituído por 28 pais de deficientes auditivos decorrentes de herança autossômica recessiva, sendo 14 mulheres com idade entre 20 a 55 anos (média 32,8 anos) e 14 homens com idade entre 20 a 58 anos (média 35,2), e o Grupo Controle (GC). formado por indivíduos sem queixa auditiva, composto por 14 homens e 14 mulheres com idades pareadas ao GE. Os indivíduos foram submetidos aos exames de Audiometria Tonal Liminar (ATL), Imitanciometria, incluindo a timpanometria e Reflexo Acústico (RA), e EOA-PD em frequências convencionais e em frequências ultra-altas. RESULTADOS: Não houve diferença estatisticamente significante entre as orelhas e grupos nos achados da ATL e RA, porém, nas respostas de EOA-PD, o GE apresentou diferença estatisticamente significativa em todas as frequências em comparação ao GC. A Correlação de Pearson entre a ATL e as EOA-PD, entre as orelhas e entre os grupos, mostrou correlação negativa entre as orelhas e grupos, indicando que, com o aumento no nível de resposta das EOA-PD, ocorre melhora nos limiares auditivos. A correlação de Pearson entre os resultados dos RA e as EOA-PD não demonstrou correlação significativa para ambos os grupos avaliados. A correlação de Pearson entre a idade e as EOA-PD, em frequências convencionais, mostrou correlação negativa significativa em algumas frequências, entretanto, não houve correlação entre a idade e as EOA-PD em frequências ultra-altas. Foi utilizado o intervalo de referência, diagramas de dispersão e análise discriminante para investigar-se se houve diferença entre as EOA-PD em frequências convencionais e em frequências ultra-altas, sendo que as EOA-PD em frequências convencionais mensuraram com maior precisão os sujeitos do GE, em relação às frequências ultra-altas. CONCLUSÃO: As EOA-PD, tanto para as frequências convencionais, quanto para as frequências ultra-altas, foram capazes de distinguir os indivíduos do GE e do GC, sugerindo que indivíduos heterozigotos para a mutação do gene GJB2 podem apresentar dano no processo ativo das células ciliadas externas antes da manifestação clínica por meio dos resultados alterados na avaliação audiológica convencional. / INTRODUCTION: In nonsyndromic hearing loss of recessive autosomal heritage, caused by changes in the gene GJB2 (Gap Junction Bet-2 Protein), parents of individuals with hearing loss are heterozygous carriers of a recessive allele which causes deafness, however, are asymptomatic, but may present early and mild hearing changes. OBJECTIVE: Assessing the cochlear function in parents of individuals with hearing loss of recessive autosomal heritage through Distortion Product Otoacoustic Emissions (DPOAE) in conventional frequencies and in ultra-high frequencies, comparing the responses of the control group paired by gender and age. METHOD: 56 individuals were assessed, aged between 20 and 58 years old, divided into two groups, the Study Group (GE), composed of 28 parents of hearing impaired people due to recessive autosomal heritage, 14 women being 20 to 55 years old (32.8 years old average) and 14 men being 20 to 58 years (35.2 years old average), and the Control Group (GC) formed by individuals without hearing complaints, composed of 14 men and 14 women being paired according to the age of GE. The individuals underwent examinations of Pure Tone Audiometry (PTA), Immittanciometry, including tympanometry and Acoustic Reflex (AR), and DPOAE in conventional frequencies and ultra-high frequencies. RESULTS: There was no statistically significant difference between the ears and the groups in the findings of PTA and AR; however, in the responses of DPOAE, the GE presented a statistically significant difference in all the frequencies compared to the GC. The Pearson Correlation between PTA and DPOAE, between the ears and between the groups, showed a negative correlation between the ears and the groups, indicating that, with the increase in the level of response of DPOAE, there is improvement in hearing thresholds. The Pearson Correlation between the results of AR and DPOAE showed no significant correlation for both groups assessed. The Pearson Correlation between age and DPOAE, in conventional frequencies, showed a significant negative correlation in some frequencies, however, there was no correlation between age and DPOAE in ultra-high frequencies. Reference range, scatter plots and discriminant analysis were used to investigate whether there was a difference between DPOAE in conventional frequencies and in ultra-high frequencies, given that DPOAE in conventional frequencies measured with greater precision the individuals from GE, in relation to the ultra-high frequencies. CONCLUSION: DPOAE, both for conventional frequencies and ultra-high frequencies, were able to distinguish individuals from GE and GC, suggesting that heterozygous individuals for the mutation of GJB2 gene may present damage in the active process of external ciliated cells before the clinical manifestation via altered results in the conventional hearing-aid assessment.

This study assessed the role of otoacoustic emission screening for the early identification of noise-induced hearing loss in South African mineworkers. Transient otoacoustic emissions and distortion product otoacoustic emissions were recorded in 106 noise exposed mineworkers (212 ears) aged between 20 and 55 years, and in 17 non-exposed novice workers (34 ears) aged between 18 and 29 years. All subjects had normal hearing acuity, otoscopic examinations and immittance measurements. Four otoacoustic emission (OAE) measurements were taken per ear and repeated by a second audiologist for the evaluation of inter-test reliability. Age and number of years of noise exposure was additionally evaluated as well as the specificity and sensitivity of the tests for this population group. In general the OAEs were diminished at four KHz for both the exposed and non-exposed groups. Age was found to be the primary predictor of diminished OAE tracings. Poor inter-test reliability was obtained. These results indicate that further research is required within this population group before OAE testing can be implemented for screening for noise-induced hearing loss. / Dissertation (M (Communication Pathology))--University of Pretoria, 2006. / Speech-Language Pathology and Audiology / Unrestricted