Reliability of contralateral suppression of otoacoustic emissions in children.

OBJECTIVE: The purpose of the study was to determine the reliability in children of the medial olivocochlear reflex when measured as decibels of suppression of transiently evoked otoacoustic emissions (TEOAEs) by contralateral acoustic stimulation (CAS). DESIGN: TEOAEs with and without CAS (white noise) were measured. In each subject, measurements were performed twice. Of particular interest was the suppression of TEOAEs by CAS and its reliability. Reliability was evaluated by calculating the standard error of measurement (SEM) and minimum detectable change (MDC). STUDY SAMPLE: Fifty-one normally hearing girls aged 3-6 years. RESULTS: The average global TEOAE suppression was around 0.6 dB. The highest reliability was for global values, with SEM of 0.2 dB and MDC of ±0.55 dB for the standard 2.5-20 ms recording window and slightly higher values for an 8-18 ms window. The worst reliability in the studied group was for the 1 kHz half-octave frequency band. Additionally, ears without spontaneous otoacoustic emissions had higher suppression levels than those with, but they also had lower signal-to-noise ratios, which may limit their clinical utility. CONCLUSIONS: The current study shows that, under the studied paradigm, TEOAE suppression does not have satisfactory reliability since MDC was similar to the level of suppression.

Association between Spontaneous Otoacoustic Emission and Psychoacoustic measures.

AIM: The aim of the present study was to evaluate the association of presence and absence of spontaneous otoacoustic emissions (SOAEs) on different psycho-acoustic measures such as intensity discrimination, gap detection test, duration discrimination test, modulation detection for sinusoidal amplitude modulated noise at 8, 20, 60, and 100 Hz. METHOD: Sixty adults with hearing sensitivity within normal limits were divided into two groups; group 1 consisted of participants with SOAEs present and group 2 consisted of participants with SOAEs absent. All the participants were tested for presence of SOAEs and different psycho-acoustic measures. RESULTS: The present study results showed no significant difference on intensity discrimination, gap detection test, duration discrimination test, modulation detection for sinusoidal amplitude modulated noise at 8, 20, 60, and 100 Hz in presence and absent of SOAE. CONCLUSION: The findings reveals that the presence or absence of SOAE did not influence or enhance the psychophysical performance at most comfortable level in individuals having normal hearing.

Individual Differences in Behavioural Decision Weights Related to Irregularities in Cochlear Mechanics.

An unexpected finding of previous psychophysical studies is that listeners show highly replicable, individualistic patterns of decision weights on frequencies affecting their performance in spectral discrimination tasks--what has been referred to as individual listening styles. We, like many other researchers, have attributed these listening styles to peculiarities in how listeners attend to sounds, but we now believe they partially reflect irregularities in cochlear micromechanics modifying what listeners hear. The most striking evidence for cochlear irregularities is the presence of low-level spontaneous otoacoustic emissions (SOAEs) measured in the ear canal and the systematic variation in stimulus frequency otoacoustic emissions (SFOAEs), both of which result from back-propagation of waves in the cochlea. SOAEs and SFOAEs vary greatly across individual ears and have been shown to affect behavioural thresholds, behavioural frequency selectivity and judged loudness for tones. The present paper reports pilot data providing evidence that SOAEs and SFOAEs are also predictive of the relative decision weight listeners give to a pair of tones in a level discrimination task. In one condition the frequency of one tone was selected to be near that of an SOAE and the frequency of the other was selected to be in a frequency region for which there was no detectable SOAE. In a second condition the frequency of one tone was selected to correspond to an SFOAE maximum, the frequency of the other tone, an SFOAE minimum. In both conditions a statistically significant correlation was found between the average relative decision weight on the two tones and the difference in OAE levels.

Carbamazepine induces upward frequency shifts of spontaneous otoacoustic emissions.

In three subjects, we measured spontaneous otoacoustic emissions (SOAEs) when they were using carbamazepine (CBZ), and compared this to the SOAE measurement when they were not using CBZ. We observed 14 SOAEs showing a consistent upward shift of center frequency, related to CBZ intake. On average, the magnitude of the frequency shift increased with increasing frequency. The magnitude of the shift was 30-104 Hz, at frequencies ranging from 1.3 to 2.3 kHz, corresponding to a shift between 2.3 and 4.5%. Compared to other causes and manipulations known to change SOAE frequency, these shifts are relatively large. The underlying mechanism is most likely an increased stiffness of the cochlear partition. This would also explain the downward pitch shift due to CBZ, which has been reported by subjects with absolute pitch.

Whistling While it Works: Spontaneous Otoacoustic Emissions and the Cochlear Amplifier.

Perhaps the most striking evidence for active processes operating within the inner ears of mammals and non-mammals alike is their ability to spontaneously produce sound. Predicted by Thomas Gold in 1948, some 30 years prior to their discovery, the narrow-band sounds now known as spontaneous otoacoustic emissions (SOAEs) remain incompletely understood, their origins controversial. Without a single equation in the main text, we review the essential concepts underlying the "local-" and "global-oscillator" frameworks for understanding SOAE generation. Comparing their key assumptions and predictions, we relate the two frameworks to unresolved questions about the biophysical mechanisms of cochlear amplification.

Comparing spontaneous and stimulus frequency otoacoustic emissions in mice with tectorial membrane defects.

The global standing-wave model for generation of spontaneous otoacoustic emissions (SOAEs) suggests that they are amplitude-stabilized standing waves and that the spacing between SOAEs corresponds to the interval over which the phase changes by one cycle as determined from the phase-gradient delays of stimulus frequency otoacoustic emissions (SFOAEs). Because data characterizing the relationship between spontaneous and evoked emissions in nonhuman mammals are limited, we examined SOAEs and SFOAEs in tectorial membrane (TM) mutants and their controls. Computations indicate that the spacing between adjacent SOAEs is predicted by the SFOAE phase-gradient delays for TM mutants lacking Ceacam16, where SOAE frequencies are greater than ~20 kHz and the mutants retain near-normal hearing when young. Mice with a missense mutation in Tecta (TectaY1870C/+), as well as mice lacking Otoancorin (Otoa-/-), were also examined. Although these mutants exhibit hearing loss, they generate SOAEs with average frequencies of 11 kHz in TectaY1870C/+ and 6 kHz in Otoa-/-. In these animals, the spacing between adjacent SOAEs is larger than predicted by the SFOAE phase delays. It is also demonstrated that mice do not exhibit the strong frequency-dependence in signal coding that characterizes species with good low-frequency hearing. In fact, a transition occurs near the apical end of the mouse cochlea rather than at the mid-point along the cochlear partition. Hence, disagreements with the standing-wave model are not easily explained by a transition in tuning ratios between apical and basal regions of the cochlea, especially for SOAEs generated in TectaY1870C/+mice.

Spontaneous otoacoustic emissions are biomarkers for mice with tectorial membrane defects.

Cochlear function depends on the operation of a coupled feedback loop, incorporating outer hair cells (OHCs), and structured to assure that inner hair cells (IHCs) convey frequency specific acoustic information to the brain, even at very low sound levels. Although our knowledge of OHC function and its contribution to cochlear amplification has expanded, the importance of the tectorial membrane (TM) to the processing of mechanical inputs has not been fully elucidated. In addition, there are a surprising number of genetic mutations that affect TM structure and that produce hearing loss in humans. By synthesizing old and new results obtained on several mouse mutants, we learned that animals with abnormal TMs are prone to generate spontaneous otoacoustic emissions (SOAE), which are uncommon in most wildtype laboratory animals. Because SOAEs are not produced in TM mutants or in humans when threshold shifts exceed approximately 25 dB, some degree of cochlear amplification is required. However, amplification by itself is not sufficient because normal mice are rarely spontaneous emitters. Since SOAEs reflect active cochlear operation, TM mutants are valuable for studying the oscillatory nature of the amplification process and the structures associated with its stabilization. Inasmuch as the mouse models were selected to mirror human auditory disorders, using SOAEs as a noninvasive clinical tool may assist the classification of individuals with genetic defects that influence the active mechanisms responsible for sensitivity and frequency selectivity, the hallmarks of mammalian hearing.

The characteristic of otoacoustic emissions in full-term neonates according to ABO blood groups.

INTRODUCTION: Previous research has suggested that individuals with different blood groups show varied incidences of noise-induced hearing loss. The reduced otoacoustic emissions amplitudes indicate the higher possibilities of outer hair cell damage for noise exposure. OBJECTIVE: The objective is to analyze the characteristics of otoacoustic emissions, including the occurrence of spontaneous otoacoustic emission and the amplitudes of distortion product otoacoustic emission at certain frequencies in full term neonates with different ABO blood groups. METHODS: A total of 80 selected full-term female neonates who passed the initial newborn hearing screen were enrolled into the study, with equal number of participants in four ABO blood groups (Blood Group A, Blood Group B, Blood Group AB, Blood Group O). Measurements of spontaneous otoacoustic emission and distortion product otoacoustic emission were performed in both ears for all participants. RESULTS: (1) The blood group O participants showed significantly fewer spontaneous otoacoustic emission occurrences than the other three blood groups (A=70%, B=80%, AB=67%, O=25%, p< 0.05). (2) The blood group O participants showed lower DPOAE amplitudes at 1257 Hz (M = 4.55 dB, SD = 8.36), 1587 Hz (M = 11.60 dB, SD = 6.57), 3174 Hz (M = 7.25 dB, SD = 5.99), 5042 Hz (M = 13.60, SD = 6.70) than participants with the other three blood groups in left ears (p < 0.05). In right ears, the blood group O participants showed reduced amplitudes at 1257Hz (M=6.55dB, SD=8.36), 1587Hz (M=13.60dB, SD=6.57), 3174Hz (M=7.65dB, SD=6.43), 5042Hz (M=13.65dB, SD=6.50) than participants from non-O blood groups (p<0.05). CONCLUSION: Female individuals with blood group O have lower otoacoustic emissions values than individuals with the other three blood groups. We need to further investigate the possible relationships between ABO blood group and cochlear function, including the potential influences of noise damage on cochlear outer hair cells.

Accelerated Age-Related Degradation of the Tectorial Membrane in the Ceacam16ßgal/ßgal Null Mutant Mouse, a Model for Late-Onset Human Hereditary Deafness DFNB113.

CEACAM16 is a non-collagenous protein of the tectorial membrane, an extracellular structure of the cochlea essential for normal hearing. Dominant and recessive mutations in CEACAM16 have been reported to cause postlingual and progressive forms of deafness in humans. In a previous study of young Ceacam16ßgal/ßgal null mutant mice on a C57Bl/6J background, the incidence of spontaneous otoacoustic emissions (SOAEs) was greatly increased relative to Ceacam16+/+ and Ceacam16+/ßgal mice, but auditory brain-stem responses (ABRs) and distortion product otoacoustic emissions (DPOAEs) were near normal, indicating auditory thresholds were not significantly affected. To determine if the loss of CEACAM16 leads to hearing loss at later ages in this mouse line, cochlear structure and auditory function were examined in Ceacam16+/+, Ceacam16+/ßgal and Ceacam16ßgal/ßgal mice at 6 and 12 months of age and compared to that previously described at 1 month. Analysis of older Ceacam16ßgal/ßgal mice reveals a progressive loss of matrix from the core of the tectorial membrane that is more extensive in the apical, low-frequency regions of the cochlea. In Ceacam16ßgal/ßgal mice at 6-7 months, the DPOAE magnitude at 2f1-f2 and the incidence of SOAEs both decrease relative to young animals. By ∼12 months, SOAEs and DPOAEs are not detected in Ceacam16ßgal/ßgal mice and ABR thresholds are increased by up to ∼40 dB across frequency, despite a complement of hair cells similar to that present in Ceacam16+/+ mice. Although SOAE incidence decreases with age in Ceacam16ßgal/ßgal mice, it increases in aging heterozygous Ceacam16+/ßgal mice and is accompanied by a reduction in the accumulation of CEACAM16 in the tectorial membrane relative to controls. An apically-biased loss of matrix from the core of the tectorial membrane, similar to that observed in young Ceacam16ßgal/ßgal mice, is also seen in Ceacam16+/+ and Ceacam16+/ßgal mice, and other strains of wild-type mice, but at much later ages. The loss of Ceacam16 therefore accelerates age-related degeneration of the tectorial membrane leading, as in humans with mutations in CEACAM16, to a late-onset progressive form of hearing loss.

Spontaneous Otoacoustic Emissions in TectaY1870C/+ Mice Reflect Changes in Cochlear Amplification and How It Is Controlled by the Tectorial Membrane.

Spontaneous otoacoustic emissions (SOAEs) recorded from the ear canal in the absence of sound reflect cochlear amplification, an outer hair cell (OHC) process required for the extraordinary sensitivity and frequency selectivity of mammalian hearing. Although wild-type mice rarely emit, those with mutations that influence the tectorial membrane (TM) show an incidence of SOAEs similar to that in humans. In this report, we characterized mice with a missense mutation in Tecta, a gene required for the formation of the striated-sheet matrix within the core of the TM. Mice heterozygous for the Y1870C mutation (TectaY1870C/+ ) are prolific emitters, despite a moderate hearing loss. Additionally, Kimura's membrane, into which the OHC stereocilia insert, separates from the main body of the TM, except at apical cochlear locations. Multimodal SOAEs are also observed in TectaY1870C/+ mice where energy is present at frequencies that are integer multiples of a lower-frequency SOAE (the primary). Second-harmonic SOAEs, at twice the frequency of a lower-frequency primary, are the most frequently observed. These secondary SOAEs are found in spatial regions where stimulus-evoked OAEs are small or in the noise floor. Introduction of high-level suppressors just above the primary SOAE frequency reduce or eliminate both primary and second-harmonic SOAEs. In contrast, second-harmonic SOAEs are not affected by suppressors, either above or below the second-harmonic SOAE frequency, even when they are much larger in amplitude. Hence, second-harmonic SOAEs do not appear to be spatially separated from their primaries, a finding that has implications for cochlear mechanics and the consequences of changes to TM structure.

Validação de simulador de emissões otoacústicas para o ensino em audiologia / Otoacoustic emissions simulator validation for audiology education / Validación del simulador de emisiones otoacuticas para la educación en audiología

O teste Emissões Otoacústicas (EOA) é parte da avaliação Audiológica para detecção precoce da surdez na infância. Desse modo, o aprendizado das EOA na graduação do curso de Fonoaudiologia é fundamental conforme a Diretriz Curricular Nacional (DCN). As diretrizes educacionais sugerem a inclusão de tecnologias de informação no ensino da graduação para melhor desempenho dos futuros profissionais da saúde. Objetivo: Validar o protótipo simulador OTOBABY para o Teste de Emissões Otoacústicas como ferramenta de ensino em Fonoaudiologia. Metodologia: Trata-se de uma pesquisa metodológica, experimental, com a participação de dez fonoaudiólogos professores e/ou preceptores, denominados juízes e 20 alunos de graduação de Fonoaudiologia em Belém do Pará/Brasil. Os juízes responderam a um questionário de validação de Escala Likert sobre a usabilidade e efetividade do simulador OTOBABY como ferramenta de ensino. Os alunos participaram de um curso de capacitação com o uso do protótipo e foram avaliados com checklists antes e depois do curso para a verificação da eficácia do simulador como instrumento de ensino. Os dados foram analisados estatisticamente com o teste de Wilcoxon. Resultados: O simulador alcançou 98% de aprovação como ferramenta de ensino para as EOA pelos juízes. Quanto a habilidade dos alunos, observou-se que era de 60,3%, antes do curso, obtendo-se um desempenho de 97,7% após curso com o OTOBABY. Conclusão: Conclui-se que o protótipo simulador OTOBABY foi aprovado e validado como um instrumento facilitador do aprendizado das Emissões Otoacústicas no ensino da prática Audiológica.

The Otoacoustic Emissions (OAE) test is part of the Audiological evaluation for early detection of childhood deafness. Thus, the learning of OAE in the undergraduate course of Speech Therapy is fundamental according to the National Curriculum Guideline (NCD). The educational guidelines suggest the inclusion of information technologies in undergraduate education for better performance of future health professionals. Objective: Validate the prototype OTOBABY simulator for the Otoacoustic Emissions Test as a teaching tool in Speech Therapy. Methodology: This is a methodological, experimental research, with the participation of ten phonoaudiologists, professors and/or preceptors, called judges and 20 undergraduate students of Speech Therapy in Belém do Pará/Brazil. The judges responded to a Likert Scale validation questionnaire on the usability and effectiveness of the OTOBABY simulator as a teaching tool. Students took part in a training course using the prototype and were evaluated with checklists before and after the course to verify the simulator's effectiveness as a teaching instrument. The data were statistically analyzed with the Wilcoxon test. Results: The simulator achieved 98% approval as a teaching tool for OAE by the judges. As for the ability of the students, it was observed that it was 60.3%, before the course, obtaining a performance of 97.7% after course with OTOBABY. Conclusion: It is concluded that the prototype simulator OTOBABY was approved and validated as a facilitator instrument of the learning of Otoacoustic Emissions in the teaching of Audiological practice.

La prueba EOA es parte de la evaluación auditiva para la sordera temprana en la niñez. En consecuencia, el aprendizaje de las EOA en el curso de posgrado de fonoaudiología es fundamental de acuerdo con la Directriz Nacional de Planes de Estudio (NCN). Las directrices educativas sugieren la inclusión de las tecnologías de la información en la enseñanza de cursos de pregrado para mejorar el desempeño de futuros profesionales de la salud. Objetivo: Validar el prototipo de simulador OTOBABY para la Prueba de Emisiones Otoacústicas como herramienta docente en fonoaudiología. Metodología: Estamos tratando con la investigación metodológica, experimental, con la participación de diez audiólogos de idiomas, profesores y/o preceptores, llamados jueces y 20 estudiantes universitarios de fonoaudiología en Belém do Pará/Brasil. Los jueces respondieron a un cuestionario de validación de la Escala Likert sobre la utilidad y la eficacia del simulador OTOBABY como instrumento de enseñanza. Los estudiantes participaron en un curso de capacitación utilizando el prototipo y fueron evaluados con checklists de verificación antes y después del curso para verificar la efectividad del simulador como instrumento educativo. Los datos se analizaron estadísticamente con el test de Wilcoxon. Resultados: El simulador alcanzó el 98% de la aprobación como herramienta de enseñanza para la EOA por parte de los jueces. En cuanto a la capacidad de los estudiantes, se observó que era del 60,3% antes del curso, alcanzando un desempeño del 97,7% después del curso con OTOBABY. Conclusión: Se concluye que el prototipo de simulador OTOBABY ha sido aprobado y validado como instrumento que facilita el aprendizaje de emisiones ópticas en la enseñanza de la práctica audiológica.

Estudo das emissões otoacústicas residuais nas perdas auditivas neurossensoriais com diferenciação de artefatos e respostas fisiológicas / Study of residual otoacoustic emissions in hearing loss with artifact differentiation and physiological responses

RESUMO Objetivo avaliar o efeito da variação da intensidade de estimulação sobre as respostas das emissões otoacústicas produto de distorção em indivíduos com perda auditiva neurossensorial, utilizando um protocolo de gradiente de fase das emissões. Métodos estudo observacional transversal. Participaram 38 indivíduos com diagnóstico de perda auditiva neurossensorial de grau leve, moderado ou severo. Foram realizadas anamnese, meatoscopia, audiometria tonal liminar, logoaudiometria, imitanciometria, emissões otoacústicas produto de distorção e emissões otoacústicas residuais. As emissões otoacústicas residuais foram coletadas com o equipamento Echodia, modelo Elios®. O protocolo utilizado permite a variação dos parâmetros frequência e intensidade e as respostas são analisadas por meio do teste do Gradiente de Fase. As respostas registradas nas emissões residuais foram consideradas como "presente", "ausente" e "artefato", considerando a variação da fase em função de f1. Resultados Foram incluídas 72 orelhas. Houve diferença estatisticamente significativa nas frequências de 1300 Hz e 2000 Hz, ao comparar os resultados das emissões residuais. Ao correlacionar o resultado da audiometria e a intensidade de estimulação que evocou a emissão residual, houve correlação positiva para as frequências de 1000 Hz e 4000Hz. O "artefato" foi registrado, principalmente, nas frequências mais agudas: 56,2% em 3000 Hz e 58,2% em 4000 Hz. A emissão otoacústica residual presente foi registrada em 18,6% em 1000 Hz, 13,4% em 2000 Hz, 6,3% em 3000 Hz e 7,5% em 4000 Hz. Conclusão o aumento da intensidade de estimulação no exame de emissões pode auxiliar no estudo das células ciliadas residuais, desde que seja utilizado um protocolo capaz de diferenciar respostas fisiológicas de artefatos.

ABSTRACT Purpose To study the effect of stimulation intensity variation on the responses of distortion products in subjects with sensorineural hearing loss using a new protocol to register the otoacoustic emissions. Methods This is a cross-sectional observational study. The following procedures were performed: anamnesis, otoscopy, pure tone audiometry, speech audiometry, tympanometry, distortion product and residual otoacoustic emissions. The residual DPOAE were collected with the Echodia equipment, Elios®. The protocol that was developed allows the variation of frequency and intensity parameters and the responses are analyzed by phase gradient test. Responses recorded in residual otoacoustic emissions were considered "present", "absent" or "artifact". Results The total included ears was 72. On residual otoacoustic emissions test, at a frequency of 1300Hz and 2000Hz, there was statistically significant difference. By analyzing the average found in the audiometry and the results of residual emissions, only the frequency of 1300Hz showed a statistically significant association in all groups. By correlating the results of the audiometry and the stimulation intensity used to evoke the residual emission, there was positive correlation for the frequencies of 1000Hz and 4000Hz. The "artifact" was mostly recorded in the higher frequencies: 56.2% in 3000Hz and 58.2% in 4000 Hz. Residual EOAPD present was recorded as 18.6% at 1000Hz, 13.4% at 2000Hz, 6.3% at 3000Hz and 7.5% at 4000Hz. Conclusion The increased stimulation intensity in the otoacoustic emissions test can aid in the study of residual outer hair cells, as long as a protocol is used to check the correctness of the responses.

Spontaneous otoacoustic emissions in schoolchildren.

OBJECTIVE: Spontaneous otoacoustic emissions (SOAEs) are one of the least studied types of otoacoustic emissions (OAEs). The purpose of this study was twofold: first, to determine the prevalence of SOAEs in schoolchildren, and second to test whether there was dependence between the presence or absence of SOAEs in a subject and the corresponding level of their transiently evoked OAEs (TEOAEs). METHODS: Measurements were made on a group of normally hearing children of age 7-13 years. A technique which detects synchronized SOAEs (SSOAEs) was used in which the response to repetitive clicks (12.5/s) was analyzed in the 60-80 ms time window following each click. The matching pursuit method was used to detect SSOAEs components above the noise in this window. For comparison, TEOAEs evoked by clicks (40/s) were obtained using the standard nonlinear protocol (20 ms time window). RESULTS: The prevalence of SOAEs was 37%, and higher in females and right ears. There was an average of 2.3 SOAEs per emitting ear. TEOAE levels were higher for ears that had SOAEs and were lower for ears that did not have any SOAEs. CONCLUSION: Although not all normal human have SOAEs, they appear to reflect an important aspect of cochlear function. Their presence is strongly related to elevated levels of TEOAEs which are routinely used in audiological tests.

Increased Spontaneous Otoacoustic Emissions in Mice with a Detached Tectorial Membrane.

Mutations in genes encoding tectorial membrane (TM) proteins are a significant cause of human hereditary hearing loss (Hildebrand et al. 2011), and several mouse models have been developed to study the functional significance of this accessory structure in the mammalian cochlea. In this study, we use otoacoustic emissions (OAE), signals obtained from the ear canal that provide a measure of cochlear function, to characterize a mouse in which the TM is detached from the spiral limbus due to an absence of otoancorin (Otoa, Lukashkin et al. 2012). Our results demonstrate that spontaneous emissions (SOAE), sounds produced in the cochlea without stimulation, increase dramatically in mice with detached TMs even though their hearing sensitivity is reduced. This behavior is unusual because wild-type (WT) controls are rarely spontaneous emitters. SOAEs in mice lacking Otoa predominate around 7 kHz, which is much lower than in either WT animals when they generate SOAEs or in mutant mice in which the TM protein Ceacam16 is absent (Cheatham et al. 2014). Although both mutants lack Hensen's stripe, loss of this TM feature is only observed in regions coding frequencies greater than ~15 kHz in WT mice so its loss cannot explain the low-frequency, de novo SOAEs observed in mice lacking Otoa. The fact that ~80 % of mice lacking Otoa produce SOAEs even when they generate smaller distortion product OAEs suggests that the active process is still functioning in these mutants but the system(s) involved have become less stable due to alterations in TM structure.

Efeito inibitório da via eferente auditiva no transtorno de processamento auditivo central / Auditory efferent inhibitory effect in central auditory processing disorder

RESUMO Objetivo verificar e comparar a ocorrência e magnitude do efeito inibitório da via auditiva eferente em crianças e adolescentes com processamento auditivo normal e alterado, identificando um valor de corte para uso na prática clínica. Métodos estudo prospectivo, com amostra composta por 30 crianças de 7 a 14 anos, sendo 15 com avaliação de processamento auditivo normal (grupo controle) e 15 com processamento auditivo alterado (grupo estudo). Ambos os grupos foram submetidos à anamnese e avaliados por meio dos testes de emissões otoacústicas evocadas por estímulos transientes na ausência e presença de ruído contralateral, avaliação audiológica básica e de processamento auditivo. Resultados houve menor ocorrência do efeito inibitório da via eferente no grupo estudo (p-valor=0,038). Os valores médios obtidos no grupo controle foram 0,71 na orelha direita e 0,87 na orelha esquerda e no grupo estudo, 0,55 na orelha direita e 0,41 na orelha esquerda. Os grupos controle e estudo diferiram de modo significativo na orelha esquerda. Conclusão houve redução do efeito inibitório da via eferente em crianças e adolescentes com transtorno de processamento auditivo, sugerindo alteração funcional do sistema eferente olivococlear medial. O valor que separou as crianças com e sem alteração do sistema eferente foi de 0,55 dB na prática clínica, com 70% de sensibilidade e 66,7% de especificidade.

ABSTRACT Purpose Verify and compare the occurrence and magnitude of the inhibitory effect of the efferent auditory pathway in children and adolescents with normal and auditory processing disorder, identifying a cutoff value to use in clinical settings. Methods A prospective study, with a total sample of 30 children aged 7 to 14 years, half with normal auditory processing assessment (Control Group) and the other half with auditory processing disorder (Study Group). Both groups were submitted to anamnesis and evaluated using the otoacoustic emissions tests evoked by transient stimuli in the absence and presence of contralateral noise, basic audiological evaluation and auditory processing. Results The study group presented a lower occurrence of the inhibitory effect of the efferent pathway when compared to the control group (p value=0.038). The mean values ​​obtained for the control group were 0.71 in the right ear and 0.87 in the left ear and for the study group, 0.55 in the right ear and 0.41 in the left ear. The two groups showed a statistically significant difference for the left ear. Conclusion There was a reduction in the inhibitory effect of the efferent pathway in children and adolescents with auditory processing disorder, suggesting a functional change in the medial olivocochlear efferent system. In this study, the cutoff value of 0.55 dB separated children with and without alteration of the efferent system with 70% sensitivity and 66.7% specificity.

Concurrent Acoustic Activation of the Medial Olivocochlear System Modifies the After-Effects of Intense Low-Frequency Sound on the Human Inner Ear.

>Human hearing is rather insensitive for very low frequencies (i.e. below 100 Hz). Despite this insensitivity, low-frequency sound can cause oscillating changes of cochlear gain in inner ear regions processing even much higher frequencies. These alterations outlast the duration of the low-frequency stimulation by several minutes, for which the term 'bounce phenomenon' has been coined. Previously, we have shown that the bounce can be traced by monitoring frequency and level changes of spontaneous otoacoustic emissions (SOAEs) over time. It has been suggested elsewhere that large receptor potentials elicited by low-frequency stimulation produce a net Ca(2+) influx and associated gain decrease in outer hair cells. The bounce presumably reflects an underdamped, homeostatic readjustment of increased Ca(2+) concentrations and related gain changes after low-frequency sound offset. Here, we test this hypothesis by activating the medial olivocochlear efferent system during presentation of the bounce-evoking low-frequency (LF) sound. The efferent system is known to modulate outer hair cell Ca(2+) concentrations and receptor potentials, and therefore, it should modulate the characteristics of the bounce phenomenon. We show that simultaneous presentation of contralateral broadband noise (100 Hz-8 kHz, 65 and 70 dB SPL, 90 s, activating the efferent system) and ipsilateral low-frequency sound (30 Hz, 120 dB SPL, 90 s, inducing the bounce) affects the characteristics of bouncing SOAEs recorded after low-frequency sound offset. Specifically, the decay time constant of the SOAE level changes is shorter, and the transient SOAE suppression is less pronounced. Moreover, the number of new, transient SOAEs as they are seen during the bounce, are reduced. Taken together, activation of the medial olivocochlear system during induction of the bounce phenomenon with low-frequency sound results in changed characteristics of the bounce phenomenon. Thus, our data provide experimental support for the hypothesis that outer hair cell calcium homeostasis is the source of the bounce phenomenon.

Tone burst evoked otoacoustic emissions in different age-groups of schoolchildren.

INTRODUCTION: Otoacoustic emissions (OAEs) are believed to be good predictors of hearing status, particularly in the 1-4kHz range. However both click evoked OAEs (CEOAEs) and distortion product OAEs (DPOAEs) perform poorly at 0.5kHz. The present study investigates OAEs in the lower frequency range of 0.5-1kHz evoked by 0.5kHz tone bursts (TBOAEs) in schoolchildren and compares them with emissions evoked by clicks. METHODS: Measurements were performed for two groups of normally hearing schoolchildren. Children from 1st grade (age 6-7 years) and children from 6th grade (age 11-12 years). Tympanometry, pure tone audiometry, and OAE measurements of CEAOEs, 0.5kHz TBOAEs, and spontaneous OAEs (SOAEs) were performed. Additionally, analysis by the matching pursuit method was conducted on CEOAEs and TBOAEs to assess their time-frequency (TF) properties. RESULTS: For all subjects OAEs response levels and signal to noise ratios (SNRs) were calculated. As expected, CEOAE magnitudes were greatest over the range 1-4kHz, with a substantial decrease below 1kHz. Responses from the 0.5kHz TBOAEs were complementary in that the main components occurred between 0.5 and 1.4kHz. In younger children, TBOAEs had SNRs 4-8dB smaller in the 0.5-1.4kHz range. In addition, CEOAEs had lower SNRs in the 0.7-1.4kHz range, by 3-5dB. TBOAEs in younger children had maximum SNRs shifted toward 1-1.4kHz, whereas in older children it was more clearly around 1kHz. The differences in response levels were less evident. The presence of SOAEs appreciably influenced both CEOAEs and TBOAEs, and TF properties of both OAEs did not differ significantly between grades. CONCLUSION: TBOAEs evoked at 0.5kHz can provide additional information about frequencies below 1kHz, a range over which CEOAEs usually have very low amplitudes. The main difference between the two age groups was that in older children CEOAEs and 0.5kHz TBOAEs had higher SNRs at 0.5-1.4kHz. Additionally, for ears with SOAEs, 0.5kHz TBOAEs had higher response levels and SNRs similar to CEOAEs.

Efferent inhibition of otoacoustic emissions in preterm neonates.

INTRODUCTION: Abnormalities in auditory function of newborns may occur not only because of preterm birth, but also from the use of medications and from diseases related to prematurity. OBJECTIVE: To analyze the inhibitory effect from stimulation of the olivocochlear efferent system on transient evoked otoacoustic emissions in preterm neonates, comparing these data with those from full-term neonates. METHODS: This was a prospective, cross-sectional, contemporary cohort study with 125 neonates, pooled into two groups: full-term (72 full-term neonates, 36 females and 36 males, born at 37-41 weeks of gestational age); and preterm (53 neonates, 28 males and 25 females, born at ≤36 weeks of gestational age, evaluated at the corrected gestational age of 37-41 weeks). Otoacoustic emissions were recorded using linear and nonlinear click-evoked stimuli, with and without contralateral stimulation. RESULTS: The inhibitory effect of the efferent pathway in otoacoustic emissions was different (p=0.012) between groups, and a mean reduction of 1.48dB SPL in full-term births and of 1.02dB SPL in preterm births was observed for the non-linear click-evoked stimulus. CONCLUSION: The results suggest a reduced inhibitory effect of the olivocochlear efferent system on otoacoustic emissions in preterm neonates.

A influência das curvas timpanométricas nos resultados das emissões otoacústicas / The influence of tympanometric curves on the results of otoacoustic emissions

RESUMO Objetivo Analisar as emissões otoacústicas evocadas produto de distorção (EOAPD) de indivíduos adultos entre 18 e 50 anos, com audição normal, e associar os resultados com os achados à timpanometria. Métodos Foram selecionados 27 prontuários de adultos com audição dentro dos padrões de normalidade, sem queixa auditiva, com curva timpanométrica do tipo A, Ad ou Ar, presença de reflexos acústicos, sem queixa de zumbido e de exposição frequente a níveis de pressão sonora elevados, com repouso auditivo mínimo de 14 horas no momento do exame e que realizaram o exame de emissões otoacústicas evocadas produto de distorção. Os resultados do exame de emissões otoacústicas foram analisados considerando os resultados das curvas timpanométricas apresentadas por estes indivíduos. Para análise dos dados foram aplicados testes não paramétricos e o nível de significância foi de 5%. Resultados foram analisados os resultados das emissões otoacústicas de 54 orelhas. Observou-se maior ocorrência da curva do tipo A em indivíduos sem queixas auditivas. Independente do lado, a maioria das orelhas que apresentou resposta presente ao exame de EOAPD, apresentou, também, curva timpanométrica normal. Observou-se correlação positiva entre a amplitude das EOAPD e o volume da orelha média para as frequências de 6000 Hz e uma tendência à significância em 4000 Hz Conclusão Foi possível concluir que há maior ocorrência de emissões otoacústicas presentes em indivíduos com audição normal e curva timpanométrica do tipo A e que a amplitude das EOAPD em 6000 Hz mostra-se menor nos indivíduos com audição normal e curva timpanométrica do tipo Ar ou Ad.

ABSTRACT Purpose To analyze distortion product evoked otoacoustic emissions in normal-hearing adults aged between 18 and 50 years old, and to associate the results with the findings of tympanometry. Methods 27 medical records were selected of adults with the following conditions: normal hearing; without auditory complaint; with type A, Ad or Ar tympanometric curve; with presence of acoustic reflexes; with no complaint of tinnitus or frequent exposure to high sound pressure levels; with minimal auditory rest of 14 hours at the time of the test, and who had undergone distortion product evoked otoacoustic emission (DPOAE) testing. The results of otoacoustic emissions were analyzed considering the results of the tympanometric curves presented by these individuals. For the data analysis, non-parametric tests were applied, and the level of significance was 5%. Results The results of otoacoustic emissions of 54 ears were analyzed. There was a greater occurrence of the type A curve in individuals without auditory complaints. Regardless of side, most ears whose response was present in the DPOAE test also presented normal tympanometric curve. There was a positive correlation between DPOAE amplitude and middle ear volume for the 6000Hz frequencies (p = 0.048) and a tendency to significance at 4000Hz (p = 0.054). Conclusion There was a higher occurrence of otoacoustic emissions present in normal-hearing individuals and type A tympanometric curve, and the amplitude of DPOAE at 6000Hz was smaller in normal-hearing individuals and type Ar or Ad tympanometric curve.

The characteristic of otoacoustic emissions in full-term neonates according to ABO blood groups / Característica das emissões otoacústicas em neonatos a termo segundo grupos sanguíneos do sistema ABO

Abstract Introduction: Previous research has suggested that individuals with different blood groups show varied incidences of noise-induced hearing loss. The reduced otoacoustic emissions amplitudes indicate the higher possibilities of outer hair cell damage for noise exposure. Objective: The objective is to analyze the characteristics of otoacoustic emissions, including the occurrence of spontaneous otoacoustic emission and the amplitudes of distortion product otoacoustic emission at certain frequencies in full term neonates with different ABO blood groups. Methods: A total of 80 selected full-term female neonates who passed the initial newborn hearing screen were enrolled into the study, with equal number of participants in four ABO blood groups (Blood Group A, Blood Group B, Blood Group AB, Blood Group O). Measurements of spontaneous otoacoustic emission and distortion product otoacoustic emission were performed in both ears for all participants. Results: (1) The blood group O participants showed significantly fewer spontaneous otoacoustic emission occurrences than the other three blood groups (A = 70%, B = 80%, AB = 67%, O = 25%, p < 0.05). (2) The blood group O participants showed lower DPOAE amplitudes at 1257 Hz (M = 4.55 dB, SD = 8.36), 1587 Hz (M = 11.60 dB, SD = 6.57), 3174 Hz (M = 7.25 dB, SD = 5.99), 5042 Hz (M = 13.60, SD = 6.70) than participants with the other three blood groups in left ears (p < 0.05). In right ears, the blood group O participants showed reduced amplitudes at 1257 Hz (M = 6.55 dB, SD = 8.36), 1587 Hz (M = 13.60 dB, SD = 6.57), 3174 Hz (M = 7.65 dB, SD = 6.43), 5042 Hz (M = 13.65 dB, SD = 6.50) than participants from non-O blood groups (p < 0.05). Conclusion: Female individuals with blood group O have lower otoacoustic emissions values than individuals with the other three blood groups. We need to further investigate the possible relationships between ABO blood group and cochlear function, including the potential influences of noise damage on cochlear outer hair cells.

Resumo Introdução: Pesquisas anteriores sugeriram que indivíduos de diferentes grupos sanguíneos apresentam incidências distintas de perda auditiva induzida por ruído. As amplitudes reduzidas das emissões otoacústicas indicaram maiores ou menores possibilidades de danos às células ciliadas por exposição a ruídos. Objetivo: Analisar as características das emissões otoacústicas, inclusive a ocorrência de emissões otoacústicas espontâneas e as amplitudes de emissões otoacústicas por produto de distorção em determinadas frequências em neonatos a termo de diferentes grupos sanguíneos do sistema ABO. Método: Foram incluídos 80 neonatos a termo selecionados na triagem auditiva neonatal inicial para participar do estudo, com número igual de participantes de grupos sanguíneos do sistema ABO (grupo sanguíneo A, grupo sanguíneo B, grupo sanguíneo AB e grupo sanguíneo O). As emissões otoacústicas espontâneas e emissões otoacústicas por produto de distorção foram medidas em ambas as orelhas de todos os participantes. Resultados: (1) Os participantes do grupo sanguíneo O apresentaram ocorrências de emissões otoacústicas espontâneas significantemente menores do que os dos outros três grupos sanguíneos (A = 70%, B = 80%, AB = 67%, O = 25%, p < 0,05). (2) Os participantes do grupo sanguíneo O apresentaram amplitudes de emissões otoacústicas por produto de distorção mais baixas a 1257 Hz (M = 4,55 dB, DP = 8,36), 1587 Hz (M = 11,60 dB, DP = 6,57), 3174 Hz (M = 7,25 dB, DP = 5,99), 5042 Hz (M = 13,0, DP = 6,70) do que os participantes dos outros três grupos sanguíneos nas orelhas esquerdas (p < 0,05). Nas orelhas direitas, os participantes do grupo sanguíneo O apresentaram amplitudes reduzidas em 1257 Hz (M = 6,55 dB, DP = 8,36), 1587 Hz (M = 13,60 dB, DP = 6,57), 3174 Hz (M = 7,65 dB, DP = 6,43), 5042 Hz (M = 13,65 dB, DP = 6,50) em comparação aos participantes de grupos sanguíneos não O (p < 0,05). Conclusão: Os indivíduos do sexo feminino do grupo sanguíneo O apresentaram valores menores de emissões otoacústicas do que os indivíduos dos outros três grupos sanguíneos. É necessário continuar a investigar as possíveis relações entre o grupo sanguíneo ABO e a função coclear, inclusive as possíveis influências do dano por ruídos às células ciliadas externas da cóclea.