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1.
Sensors (Basel) ; 24(5)2024 Feb 28.
Artículo en Inglés | MEDLINE | ID: mdl-38475083

RESUMEN

This paper provides a review of various machine learning approaches that have appeared in the literature aimed at individualizing or personalizing the amplification settings of hearing aids. After stating the limitations associated with the current one-size-fits-all settings of hearing aid prescriptions, a spectrum of studies in engineering and hearing science are discussed. These studies involve making adjustments to prescriptive values in order to enable preferred and individualized settings for a hearing aid user in an audio environment of interest to that user. This review gathers, in one place, a comprehensive collection of works that have been conducted thus far with respect to achieving the personalization or individualization of the amplification function of hearing aids. Furthermore, it underscores the impact that machine learning can have on enabling an improved and personalized hearing experience for hearing aid users. This paper concludes by stating the challenges and future research directions in this area.


Asunto(s)
Audífonos , Pérdida Auditiva Sensorineural , Humanos , Pérdida Auditiva Sensorineural/rehabilitación , Aprendizaje Automático
2.
J Acoust Soc Am ; 153(1): 436, 2023 01.
Artículo en Inglés | MEDLINE | ID: mdl-36732247

RESUMEN

The middle ear muscle reflex (MEMR) in humans is a bilateral contraction of the middle ear stapedial muscle in response to moderate-to-high intensity acoustic stimuli. Clinically, MEMR thresholds have been used for differential diagnosis of otopathologies for decades. More recently, changes in MEMR amplitude or threshold have been proposed as an assessment for noise-induced synaptopathy, a subclinical form of cochlear damage characterized by suprathreshold hearing problems that occur as a function of inner hair cell (IHC) synaptic loss, including hearing-in-noise deficits, tinnitus, and hyperacusis. In animal models, changes in wideband MEMR immittance have been correlated with noise-induced synaptopathy; however, studies in humans have shown more varied results. The discrepancies observed across studies could reflect the heterogeneity of synaptopathy in humans more than the effects of parametric differences or relative sensitivity of the measurement. Whereas the etiology and degree of synaptopathy can be carefully controlled in animal models, synaptopathy in humans likely stems from multiple etiologies and thus can vary greatly across the population. Here, we explore the evolving research evidence of the MEMR response in relation to subclinical noise-induced cochlear damage and the MEMR as an early correlate of suprathreshold deficits.


Asunto(s)
Pérdida Auditiva Provocada por Ruido , Animales , Humanos , Pérdida Auditiva Provocada por Ruido/diagnóstico , Pérdida Auditiva Provocada por Ruido/etiología , Umbral Auditivo/fisiología , Cóclea/fisiología , Oído Medio , Estimulación Acústica/efectos adversos , Reflejo , Músculos , Potenciales Evocados Auditivos del Tronco Encefálico/fisiología
3.
Sensors (Basel) ; 22(16)2022 Aug 12.
Artículo en Inglés | MEDLINE | ID: mdl-36015791

RESUMEN

Adaptive dynamic range optimization (ADRO) is a hearing aid fitting rationale which involves adjusting the gains in a number of frequency bands by using a series of rules. The rules reflect the comparison of the estimated percentile occurrences of the sound levels with the audibility and comfort hearing levels of a person suffering from hearing loss. In the study reported in this paper, a previously developed machine learning method was utilized to personalize the ADRO fitting in order to provide an improved hearing experience as compared to the standard ADRO hearing aid fitting. The personalization was carried out based on the user preference model within the framework of maximum likelihood inverse reinforcement learning. The testing of ten subjects with hearing loss was conducted, which indicated that the personalized ADRO was preferred over the standard ADRO on average by about 10 times. Furthermore, a word recognition experiment was conducted, which showed that the personalized ADRO had no adverse impact on speech understanding as compared to the standard ADRO.


Asunto(s)
Implantes Cocleares , Sordera , Audífonos , Pérdida Auditiva , Percepción del Habla , Pérdida Auditiva/rehabilitación , Humanos
4.
J Acoust Soc Am ; 146(5): 3692, 2019 11.
Artículo en Inglés | MEDLINE | ID: mdl-31795685

RESUMEN

Rats make excellent models for the study of medical, biological, genetic, and behavioral phenomena given their adaptability, robustness, survivability, and intelligence. The rat's general anatomy and physiology of the auditory system is similar to that observed in humans, and this has led to their use for investigating the effect of noise overexposure on the mammalian auditory system. The current paper provides a review of the rat model for studying noise-induced hearing loss and highlights advancements that have been made using the rat, particularly as these pertain to noise dose and the hazardous effects of different experimental noise types. In addition to the traditional loss of auditory function following acoustic trauma, recent findings have indicated the rat as a useful model in observing alterations in neuronal processing within the central nervous system following noise injury. Furthermore, the rat provides a second animal model when investigating noise-induced cochlear synaptopathy, as studies examining this in the rat model resemble the general patterns observed in mice. Together, these findings demonstrate the relevance of this animal model for furthering the authors' understanding of the effects of noise on structural, anatomical, physiological, and perceptual aspects of hearing.


Asunto(s)
Modelos Animales de Enfermedad , Pérdida Auditiva Provocada por Ruido/fisiopatología , Ratas/fisiología , Estimulación Acústica/métodos , Animales , Vías Auditivas/patología , Vías Auditivas/fisiopatología , Pérdida Auditiva Provocada por Ruido/patología
5.
J Acoust Soc Am ; 146(5): 3710, 2019 11.
Artículo en Inglés | MEDLINE | ID: mdl-31795699

RESUMEN

The chinchilla animal model for noise-induced hearing loss has an extensive history spanning more than 50 years. Many behavioral, anatomical, and physiological characteristics of the chinchilla make it a valuable animal model for hearing science. These include similarities with human hearing frequency and intensity sensitivity, the ability to be trained behaviorally with acoustic stimuli relevant to human hearing, a docile nature that allows many physiological measures to be made in an awake state, physiological robustness that allows for data to be collected from all levels of the auditory system, and the ability to model various types of conductive and sensorineural hearing losses that mimic pathologies observed in humans. Given these attributes, chinchillas have been used repeatedly to study anatomical, physiological, and behavioral effects of continuous and impulse noise exposures that produce either temporary or permanent threshold shifts. Based on the mechanistic insights from noise-exposure studies, chinchillas have also been used in pre-clinical drug studies for the prevention and rescue of noise-induced hearing loss. This review paper highlights the role of the chinchilla model in hearing science, its important contributions, and its advantages and limitations.


Asunto(s)
Chinchilla/fisiología , Modelos Animales de Enfermedad , Pérdida Auditiva Provocada por Ruido/fisiopatología , Animales , Conducta Animal , Audición , Pérdida Auditiva Provocada por Ruido/etiología , Pérdida Auditiva Provocada por Ruido/patología , Humanos , Especificidad de la Especie
6.
Lancet ; 390(10098): 969-979, 2017 Sep 02.
Artículo en Inglés | MEDLINE | ID: mdl-28716314

RESUMEN

BACKGROUND: Noise-induced hearing loss is a leading cause of occupational and recreational injury and disease, and a major determinant of age-related hearing loss. No therapeutic agent has been approved for the prevention or treatment of this disorder. In animal models, glutathione peroxidase 1 (GPx1) activity is reduced after acute noise exposure. Ebselen, a novel GPx1 mimic, has been shown to reduce both temporary and permanent noise-induced hearing loss in preclinical studies. We assessed the safety and efficacy of ebselen for the prevention of noise-induced hearing loss in young adults in a phase 2 clinical trial. METHODS: In this single-centre, randomised, double-blind, placebo-controlled phase 2 trial, healthy adults aged 18-31 years were randomly assigned (1:1:1:1) at the University of Florida (Gainsville, FL, USA) to receive ebselen 200 mg, 400 mg, or 600 mg, or placebo orally twice daily for 4 days, beginning 2 days before a calibrated sound challenge (4 h of pre-recorded music delivered by insert earphones). Randomisation was done with an allocation sequence generated by an independent third party. The primary outcome was mean temporary threshold shift (TTS) at 4 kHz measured 15 min after the calibrated sound challenge by pure tone audiometry; a reduction of 50% in an ebselen dose group compared with the placebo group was judged to be clinically relevant. All participants who received the calibrated sound challenge and at least one dose of study drug were included in the efficacy analysis. All randomly assigned patients were included in the safety analysis. This trial is registered with ClinicalTrials.gov, number NCT01444846. FINDINGS: Between Jan 11, 2013, and March 24, 2014, 83 participants were enrolled and randomly assigned to receive ebselen 200 mg (n=22), 400 mg (n=20), or 600 mg (n=21), or placebo (n=20). Two participants in the 200 mg ebselen group were discontinued from the study before the calibrated sound challenge because they no longer met the inclusion criteria; these participants were excluded from the efficacy analysis. Mean TTS at 4 kHz was 1·32 dB (SE 0·91) in the 400 mg ebselen group compared with 4·07 dB (0·90) in the placebo group, representing a significant reduction of 68% (difference -2·75 dB, 95% CI -4·54 to -0·97; p=0·0025). Compared with placebo, TTS at 4 kHz was non-significantly reduced by 21% in the 200 mg ebselen group (3·23 dB [SE 0·91] vs 4·07 dB [0·90] in the placebo group; difference -0·84 dB, 95% CI -2·63 to 0·94; p=0·3542) and by 7% in the 600 mg ebselen group (3·81 dB [0·90] vs 4·07 dB [0·90] in the placebo group; difference -0·27, 95% CI -2·03 to 1·50; p=0·7659). Ebselen treatment was well tolerated across all doses and no significant differences were seen in any haematological, serum chemistry, or radiological assessments between the ebselen groups and the placebo group. INTERPRETATION: Treatment with ebselen was safe and effective at a dose of 400 mg twice daily in preventing a noise-induced TTS. These data lend support to a role of GPx1 activity in acute noise-induced hearing loss. FUNDING: Sound Pharmaceuticals.


Asunto(s)
Antiinflamatorios no Esteroideos/administración & dosificación , Azoles/administración & dosificación , Pérdida Auditiva Provocada por Ruido/prevención & control , Compuestos de Organoselenio/administración & dosificación , Adolescente , Adulto , Método Doble Ciego , Femenino , Humanos , Isoindoles , Masculino , Música , Resultado del Tratamiento , Adulto Joven
7.
Ear Hear ; 39(6): 1057-1074, 2018.
Artículo en Inglés | MEDLINE | ID: mdl-29543608

RESUMEN

OBJECTIVES: The purpose of this study was to evaluate the relationship between recreational sound exposure and potentially undiagnosed or subclinical hearing loss by assessing sound exposure history, threshold sensitivity, distortion product otoacoustic emission (DPOAE) amplitudes, and performance on the words-in-noise (WIN) test. DESIGN: Survey data were collected from 74 adult participants (14 male and 60 female), 18 to 27 years of age, recruited via advertisements posted throughout the University of Florida campus. Of these participants, 70 completed both the survey and the additional functional test battery, and their preferred listening level was measured in a laboratory setting. RESULTS: There were statistically significant relationships between hearing thresholds and DPOAE amplitude. In contrast, performance on the WIN was not reliably related to threshold sensitivity within this cohort with largely normal hearing. The two most common exposures included bars or dance clubs, followed by music player use. There were no statistically significant relationships between individual or composite measures of recreational sound exposure, including preferred listening level, years of music player use, number of reported sound exposures, previous impulse noise exposure, or previous noise-induced change in hearing, and functional measures including threshold, DPOAE amplitude, and WIN measures. Some subjects were highly consistent in listening level preferences, while others were more variable from song to song. CONCLUSIONS: No reliable relationships between common recreational sound exposure or previous noise-induced changes in hearing were found during analysis of threshold sensitivity, DPOAE amplitude, or WIN performance in this cohort. However, the study sample was predominantly female and Caucasian, which limits generalizability of the results.


Asunto(s)
Umbral Auditivo , Audición , Reproductor MP3 , Música , Ruido/efectos adversos , Adolescente , Adulto , Audiometría de Tonos Puros , Femenino , Audición/fisiología , Pérdida Auditiva Provocada por Ruido , Humanos , Masculino , Emisiones Otoacústicas Espontáneas , Riesgo , Estudiantes , Universidades , Adulto Joven
8.
Ear Hear ; 38(6): 724-735, 2017.
Artículo en Inglés | MEDLINE | ID: mdl-28678080

RESUMEN

OBJECTIVES: The purpose of this study was to examine the relationship between noise exposure history, type 1 diabetes mellitus (DM), and suprathreshold measures of auditory function. DESIGN: A cross-sectional study was conducted; 20 normal-hearing participants without type 1 DM were matched on age and sex to 20 normal-hearing participants with type 1 DM (n=40). Participants, all having normal audiometric thresholds, completed noise history questionnaires and a battery of auditory physiological tests including transient evoked otoacoustic emissions, distortion product otoacoustic emissions, and auditory brainstem responses (ABR) at 80 dB nHL and at 2 different stimulus rates in both ears. Amplitude and latency for waves I and V are presented. Statistical analysis included analysis of variance and multivariate linear regression. RESULTS: No statistically significant difference for noise exposure history, otoacoustic emissions (OAE), or ABR findings were found between type 1 DM and matched controls. Males and females showed statistically significant differences for OAE amplitudes and ABR amplitude and latencies. However, no statistically significant relationship was found between noise outcomes and OAE or ABR findings. CONCLUSIONS: No statistically significant relationship between noise history and our suprathreshold ABR or OAE findings was indicated for individuals with type 1 DM or matched controls. The lack of evidence of noise related neuropathology might be due to inadequate noise exposure or lack of comorbidities in our DM group. Implications of these findings are discussed.


Asunto(s)
Diabetes Mellitus Tipo 1/epidemiología , Exposición a Riesgos Ambientales/estadística & datos numéricos , Potenciales Evocados Auditivos del Tronco Encefálico/fisiología , Pérdida Auditiva Provocada por Ruido/epidemiología , Ruido , Emisiones Otoacústicas Espontáneas/fisiología , Adolescente , Adulto , Audiometría de Tonos Puros , Estudios de Casos y Controles , Comorbilidad , Estudios Transversales , Femenino , Pérdida Auditiva Provocada por Ruido/diagnóstico , Pérdida Auditiva Provocada por Ruido/fisiopatología , Humanos , Modelos Lineales , Masculino , Análisis Multivariante , Factores Sexuales , Encuestas y Cuestionarios , Adulto Joven
9.
Int J Audiol ; 56(10): 716-722, 2017 10.
Artículo en Inglés | MEDLINE | ID: mdl-28553744

RESUMEN

OBJECTIVE: To examine the relationship between the healthy eating index (HEI), a measure of dietary quality based on United States Department of Agriculture recommendations and report of tinnitus. DESIGN: This cross-sectional analysis was based on HEI data and report of tinnitus. STUDY SAMPLE: Data for adults between 20 and 69 years of age were drawn from the National Health and Nutrition Examination Survey (NHANES), 1999-2002. The NHANES is a programme of studies, to assess the health and nutritional status of adults and children in the United States. Two thousand one hundred and seventy-six participants were included in the analytic sample. RESULTS: Of the sample, 21.1% reported tinnitus within the past year and 11.7% reported persistent tinnitus, defined as tinnitus experienced at least monthly or greater. Controlling for age, sex, race/ethnicity, diabetes, noise exposure and smoking status, we found that with healthier diet (poorer vs. better HEI) there was decreased odds of reported persistent tinnitus [odds ratio (OR); 0.67; 95% confidence interval (CI) 0.45-0.98; p = 0.03]. CONCLUSIONS: The current findings support a possible relationship between healthier diet quality and reported persistent tinnitus.


Asunto(s)
Dieta Saludable , Audición , Estado Nutricional , Acúfeno/fisiopatología , Pruebas de Impedancia Acústica , Adulto , Anciano , Audiometría de Tonos Puros , Umbral Auditivo , Estudios Transversales , Femenino , Humanos , Modelos Logísticos , Masculino , Persona de Mediana Edad , Análisis Multivariante , Encuestas Nutricionales , Valor Nutritivo , Oportunidad Relativa , Factores Protectores , Ingesta Diaria Recomendada , Estudios Retrospectivos , Factores de Riesgo , Conducta de Reducción del Riesgo , Acúfeno/diagnóstico , Acúfeno/epidemiología , Estados Unidos/epidemiología , Adulto Joven
10.
Int J Audiol ; 55 Suppl 1: S59-71, 2016.
Artículo en Inglés | MEDLINE | ID: mdl-26821935

RESUMEN

OBJECTIVE: Firearm discharges produce hazardous levels of impulse noise that can lead to permanent hearing loss. In the present study, we evaluated the effects of suppression, ammunition, and barrel length on AR-15 rifles. DESIGN: Sound levels were measured left/right of a user's head, and 1-m left of the muzzle, per MIL-STD-1474-D, under both unsuppressed and suppressed conditions. STUDY SAMPLE: Nine commercially available AR-15 rifles and 14 suppressors were used. RESULTS: Suppressors significantly decreased peak dB SPL at the 1-m location and the left ear location. However, under most rifle/ammunition conditions, levels remained above 140 dB peak SPL near a user's right ear. In a subset of conditions, subsonic ammunition produced values near or below 140 dB peak SPL. Overall suppression ranged from 7-32 dB across conditions. CONCLUSIONS: These data indicate that (1) suppressors reduce discharge levels to 140 dB peak SPL or below in only a subset of AR-15 conditions, (2) shorter barrel length and use of muzzle brake devices can substantially increase exposure level for the user, and (3) there are significant left/right ear sound pressure differences under suppressed conditions as a function of the AR-15 direct impingement design that must be considered during sound measurements to fully evaluate overall efficacy.


Asunto(s)
Armas de Fuego , Pérdida Auditiva Provocada por Ruido/etiología , Ruido/efectos adversos , Sonido , Diseño de Equipo , Pérdida Auditiva Provocada por Ruido/prevención & control , Humanos , Personal Militar , Ruido/prevención & control , Enfermedades Profesionales/etiología , Enfermedades Profesionales/prevención & control , Exposición Profesional/efectos adversos , Exposición Profesional/prevención & control , Policia , Recreación , Espectrografía del Sonido
11.
J Am Acad Audiol ; 24(8): 725-39, 2013 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-24131608

RESUMEN

BACKGROUND: Human hearing is sensitive to sounds from as low as 20 Hz to as high as 20,000 Hz in normal ears. However, clinical tests of human hearing rarely include extended high-frequency (EHF) threshold assessments, at frequencies extending beyond 8000 Hz. EHF thresholds have been suggested for use monitoring the earliest effects of noise on the inner ear, although the clinical usefulness of EHF threshold testing is not well established for this purpose. PURPOSE: The primary objective of this study was to determine if EHF thresholds in healthy, young adult college students vary as a function of recreational noise exposure. RESEARCH DESIGN: A retrospective analysis of a laboratory database was conducted; all participants with both EHF threshold testing and noise history data were included. The potential for "preclinical" EHF deficits was assessed based on the measured thresholds, with the noise surveys used to estimate recreational noise exposure. STUDY SAMPLE: EHF thresholds measured during participation in other ongoing studies were available from 87 participants (34 male and 53 female); all participants had hearing within normal clinical limits (≤25 HL) at conventional frequencies (0.25-8 kHz). RESULTS: EHF thresholds closely matched standard reference thresholds [ANSI S3.6 (1996) Annex C]. There were statistically reliable threshold differences in participants who used music players, with 3-6 dB worse thresholds at the highest test frequencies (10-16 kHz) in participants who reported long-term use of music player devices (>5 yr), or higher listening levels during music player use. CONCLUSIONS: It should be possible to detect small changes in high-frequency hearing for patients or participants who undergo repeated testing at periodic intervals. However, the increased population-level variability in thresholds at the highest frequencies will make it difficult to identify the presence of small but potentially important deficits in otherwise normal-hearing individuals who do not have previously established baseline data.


Asunto(s)
Umbral Auditivo/fisiología , Pérdida Auditiva Provocada por Ruido/fisiopatología , Pruebas Auditivas/instrumentación , Música , Ruido , Estudiantes , Adolescente , Adulto , Audiometría de Tonos Puros , Femenino , Pérdida Auditiva Provocada por Ruido/diagnóstico , Humanos , Masculino , Valores de Referencia , Adulto Joven
12.
Noise Health ; 15(67): 398-405, 2013.
Artículo en Inglés | MEDLINE | ID: mdl-24231418

RESUMEN

In the basic sciences, many researchers now use gap pre-pulse inhibition of the acoustic startle reflex (GPIAS) to determine if an animal has tinnitus after exposure to an ototoxic drug or intense noise. Tinnitus is assumed to be present if the silent gap in an ongoing narrow band noise (NBN) fails to suppress the startle reflex response evoked by an intense noise burst. The lack of gap pre-pulse inhibition presumably occurs because tinnitus fills in the silent intervals in the background noise. To test the perceptual aspects of this hypothesis, we asked hearing impaired subjects with tinnitus if they could perceive 50 ms silent intervals presented in a NBN, which was located above, below or at the subject's tinnitus pitch. The same tests were performed on normal hearing subjects without tinnitus. All subjects, with and without tinnitus, could detect the 50 ms gaps. Thus, using the stimulus parameters similar to those employed in animal and human GPIAS studies, we found that the tinnitus percept does not fill in the silent interval in a perceptual gap detection task; however, these finding do not rule out the possibility that tinnitus interferes with pre-attentive filtering of sensory stimuli in the GPIAS sensorimotor gating paradigm.


Asunto(s)
Audiometría/métodos , Inhibición Neural , Reflejo de Sobresalto , Acúfeno/diagnóstico , Acúfeno/fisiopatología , Percepción Auditiva/fisiología , Estudios de Casos y Controles , Femenino , Pérdida Auditiva/fisiopatología , Humanos , Masculino , Persona de Mediana Edad , Sensibilidad y Especificidad , Filtrado Sensorial/fisiología
13.
J Assoc Res Otolaryngol ; 24(6): 563-574, 2023 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-38010580

RESUMEN

BACKGROUND: External-ear amplification (EEA) has been shown to vary from 5-19 dB-A in large datasets of pediatric, adolescent, and adult human participants. However, variable EEA is an overlooked characteristic that likely plays a role in individual noise-induced hearing loss (NIHL) susceptibility. A noise exposure varying 5-19 dB-A translates to high-EEA individuals theoretically experiencing 3-4 times greater NIHL risk than low-EEA individuals. OBJECTIVE: The purpose of this preliminary analysis was to test the hypothesis that higher EEA is correlated with increased noise-induced threshold shift susceptibility. DESIGN: Nine chinchillas were exposed to 4-kHz octave-band noise at 89 dB-SPL for 24 h. Auditory brainstem response thresholds were obtained pre-exposure, 24-h post-exposure, and 4-week post-exposure. Relationships between EEA and threshold shift were analyzed. RESULTS: Open-ear EEA ranged 11-19 dB-SPL, and occluded-ear EEA ranged 10-21 dB-SPL. Higher occluded-ear EEA was correlated with increased NIHL susceptibility (p = 0.04), as was lower body weight (p = 0.01). Male animals exhibited more threshold shift than female animals (p = 0.02), lower body weight than female animals (p = 0.02), and higher occluded-ear EEA (male mean = 18 dB; female mean = 15 dB). CONCLUSIONS: Taken together, increased threshold shift susceptibility was observed in the smallest animals, animals with the highest occluded-ear EEA, and in male animals (which tended to have higher occluded-ear EEA). Given the established relationship between smaller body size and higher occluded-ear EEA, these preliminary results suggest that body size (and occluded-ear EEA; a function of body size) could be a potential, underlying driver of NIHL susceptibility differences, rather than true sex differences.


Asunto(s)
Pérdida Auditiva Provocada por Ruido , Ruido , Animales , Femenino , Masculino , Humanos , Niño , Adolescente , Chinchilla , Umbral Auditivo/fisiología , Audición , Peso Corporal
14.
Hear Res ; 419: 108408, 2022 06.
Artículo en Inglés | MEDLINE | ID: mdl-34955321

RESUMEN

Hearing research findings in recent years have begun to change how we think about hearing loss and how we consider the risk of auditory damage from noise exposure. These findings include evidence of noise-induced cochlear damage in the absence of corresponding permanent threshold elevation or evidence of hair cell loss. Animal studies in several species have shown that noise exposures that produce robust but only temporary threshold shifts can permanently damage inner hair cell synaptic ribbons. This type of synaptic degeneration has also been shown to occur as a result of aging in animals and humans. The emergence of these data has motivated a number of clinical studies aimed at identifying the perceptual correlates associated with synaptopathy. The deficits believed to arise from synaptopathy include poorer hearing in background noise, tinnitus and hyperacusis (loudness intolerance). However, the findings from human studies have been mixed. Key questions remain as to whether synaptopathy reliably produces suprathreshold perceptual deficits or whether it serves as an early indicator of auditory damage with suprathreshold deficits emerging later as a function of further cochlear damage. Here, we provide an overview of both human and animal studies that explore the relationship among inner hair cell damage, including loss of afferent synapses, auditory thresholds, and suprathreshold measures of hearing.


Asunto(s)
Pérdida Auditiva Provocada por Ruido , Animales , Umbral Auditivo , Cóclea , Potenciales Evocados Auditivos del Tronco Encefálico , Audición , Hiperacusia/etiología
15.
J Assoc Res Otolaryngol ; 23(3): 379-389, 2022 06.
Artículo en Inglés | MEDLINE | ID: mdl-35378622

RESUMEN

Integration of acoustic information over time is essential for processing complex stimuli, such as speech, due to its continuous variability along the time domain. In both humans and animals, perception of acoustic stimuli is a function of both stimulus intensity and duration. For brief acoustic stimuli, as duration increases, thresholds decrease by approximately 3 dB for every doubling in duration until stimulus duration reaches 500 ms, a phenomenon known as temporal integration. Although hearing loss and damage to outer hair cells (OHC) have been shown to alter temporal integration in some studies, the role of cochlear inner hair cells (IHC) on temporal integration is unknown. Because IHC transmit nearly all acoustic information to the central auditory system and are believed to code both intensity and timing information, these sensory cells likely play a critical role in temporal integration. To test the hypothesis that selective IHC loss degrades the temporal integration function, behaviorally trained chinchillas were treated with carboplatin, a drug known to selectively destroy IHC with little to no effect on OHC in this species. Pure-tone thresholds were assessed across frequencies (1, 2, 4, 8, 12 kHz) as a function of signal duration (500, 100, 50, 10, and 5 ms). Baseline testing showed a significant effect of duration on thresholds. Threshold decreased as a function of increasing duration, as expected. Carboplatin treatment (75 mg/kg) produced a moderate to severe loss of IHC (45-85%) with little-to-no loss of OHC. Contrary to our hypothesis, post-carboplatin temporal integration thresholds showed no significant differences from baseline regardless of stimulus duration or frequency. These data suggest that few IHC are necessary for temporal integration of simple stimuli. Temporal integration may be sensitive to loss of OHC and loss of cochlear non-linearities but does not appear to be sensitive to selective IHC loss.


Asunto(s)
Células Ciliadas Auditivas Internas , Células Ciliadas Auditivas Externas , Animales , Umbral Auditivo , Carboplatino/toxicidad , Chinchilla , Cóclea
16.
J Assoc Res Otolaryngol ; 23(5): 593-602, 2022 10.
Artículo en Inglés | MEDLINE | ID: mdl-35902434

RESUMEN

The relationship between the middle ear acoustic reflex (AR) and inner hair cell (IHC) loss is currently unknown. Given that IHC are believed to convey nearly all acoustic information to the central auditory nervous system, it has been assumed that loss of IHC would significantly impact the AR. To evaluate this relationship, we assessed the presence and amplitude of the AR in chinchillas before and after treatment with carboplatin, an anticancer drug that reliably and selectively destroys IHC in this species. Baseline measures of hearing sensitivity, including auditory brainstem response (ABR) thresholds and distortion product otoacoustic emissions (DPOAE), were assessed and then re-evaluated following carboplatin treatment. Post-carboplatin ABR thresholds and DPOAE were found to be unchanged or slightly elevated; results were consistent with published reports. Our main hypothesis was that loss of IHC would abolish the reflex or significantly reduce its amplitude. Contrary to our hypothesis, the ipsilateral 226-Hz AR continued to be reliably elicited following carboplatin treatment. Post-mortem histological analysis confirmed significant IHC loss (65-85 %), but no measurable loss of outer hair cells (OHCs). Given that loss of IHC alone does not significantly reduce the 226-Hz AR, our results suggest that few IHC are needed to maintain the 226-Hz AR response. These results suggest additional studies are needed to better understand the role of IHC in the reflex arc, present opportunities to further study the reflex pathway, and could change how we use the clinical AR as a potential diagnostic tool for IHC dysfunction, including those related to IHC synaptopathy.


Asunto(s)
Células Ciliadas Auditivas Internas , Reflejo Acústico , Animales , Células Ciliadas Auditivas Internas/fisiología , Carboplatino , Chinchilla , Células Ciliadas Auditivas Externas/fisiología , Umbral Auditivo/fisiología , Potenciales Evocados Auditivos del Tronco Encefálico/fisiología , Emisiones Otoacústicas Espontáneas/fisiología
17.
Antioxid Redox Signal ; 36(16-18): 1215-1228, 2022 06.
Artículo en Inglés | MEDLINE | ID: mdl-34011160

RESUMEN

Significance: Acquired sensorineural hearing loss is a major public health problem worldwide. The leading causes of sensorineural hearing loss are noise, aging, and ototoxic medications, with the key underlying pathology being damage to the cochlea. The review focuses on the phenomenon of preconditioning, in which the susceptibility to cochlear injury is reduced by exposing the ear to a stressful stimulus. Recent Advances: Cochlear conditioning has focused on the use of mono-modal conditioning, specifically conditioning the cochlea with moderate noise exposures before a traumatic exposure that causes permanent hearing loss. Recently, cross-modal conditioning has been explored more thoroughly, to prevent not only noise-induced hearing loss, but also age-related and drug-induced hearing losses. Critical Issues: Noise exposures that cause only temporary threshold shifts (TTSs) can cause long-term synaptopathy, injury to the synapses between the inner hair cells and spiral ganglion cells. This discovery has the potential to significantly alter the field of cochlear preconditioning with noise. Further, cochlear preconditioning can be the gateway to the development of clinically deployable therapeutics. Therefore, understanding the underlying mechanisms of conditioning is crucial for optimizing clinical protection against sensorineural hearing loss. Future Directions: Before the discovery of synaptopathy, noise exposures that caused only TTSs were believed to be either harmless or potentially beneficial. Any considerations of preconditioning with noise must consider the potential for injury to the synapses. Further, the discovery of different methods to precondition the cochlea against injury will yield new avenues for protection against hearing loss in the vulnerable populations. Antioxid. Redox Signal. 36, 1215-1228.


Asunto(s)
Pérdida Auditiva Provocada por Ruido , Pérdida Auditiva Sensorineural , Umbral Auditivo , Cóclea , Pérdida Auditiva Provocada por Ruido/etiología , Pérdida Auditiva Provocada por Ruido/patología , Pérdida Auditiva Provocada por Ruido/prevención & control , Pérdida Auditiva Sensorineural/complicaciones , Pérdida Auditiva Sensorineural/patología , Humanos , Ruido
18.
J Assoc Res Otolaryngol ; 21(6): 475-483, 2020 12.
Artículo en Inglés | MEDLINE | ID: mdl-32804336

RESUMEN

Temporal resolution is essential for processing complex auditory information such as speech. In hearing impaired persons, temporal resolution, often assessed by detection of brief gaps in continuous sound stimuli, is typically poorer than in individuals with normal hearing. At low stimulus presentation levels, hearing impaired individuals perform poorly but the deficits are greatly reduced when the sensation level of the stimuli are adjusted to match their normal hearing peers. In the present study, we evaluated the effect of selective inner hair cell loss on gap detection in chinchillas treated with carboplatin, an anticancer drug that selectively damages inner hair cells and afferents in this species. Treatment with carboplatin-induced inner hair cell loss of ~ 70 % but had little effect on audiometric thresholds in quiet and produced no evidence of outer hair cell loss. In contrast, selective inner hair cell loss had a significant effect on gap detection ability across a wide range of presentation levels. These results suggest that gap detection tasks are more sensitive to inner hair cell pathology than audiometric thresholds.


Asunto(s)
Antineoplásicos/efectos adversos , Percepción Auditiva/efectos de los fármacos , Carboplatino/efectos adversos , Pérdida Auditiva/inducido químicamente , Audición/efectos de los fármacos , Animales , Chinchilla , Células Ciliadas Auditivas Internas/efectos de los fármacos , Masculino
20.
Hear Res ; 226(1-2): 244-53, 2007 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-16904853

RESUMEN

Neurophysiological studies of salicylate-induced tinnitus have generally been carried out under anesthesia, a condition that abolishes the perception of tinnitus and depresses neural activity. To overcome these limitations, measurement of salicylate induced tinnitus were obtained from rats using schedule induced polydipsia avoidance conditioning (SIPAC) and gap pre-pulse inhibition of acoustic startle (GPIAS). Both behavioral measures indicated that tinnitus was present after treatment with 150 and 250 mg/kg of salicylate; measurements with GPIAS indicated that the pitch of the tinnitus was near 16 kHz. Chronically implanted microwire electrode arrays were used to monitor the local field potentials and spontaneous discharge rate from multiunit clusters in the auditory cortex of awake rats before and after treatment with 150 mg/kg of salicylate. The amplitude of the local field potential elicited with 60 dB SPL tone bursts increased significantly 2h after salicylate treatment particularly at 16-20 kHz; frequencies associated with the tinnitus pitch. Field potential amplitudes had largely recovered 1-2 days post-salicylate when behavioral results showed that tinnitus was absent. The mean spontaneous spike recorded from the same multiunit cluster pre- and post-salicylate decreased from 22 spikes/s before treatment to 14 spikes/s 2h post-salicylate and recovered 1 day post-treatment. These preliminary physiology data suggest that salicylate induced tinnitus is associated with sound evoked hyperactivity in auditory cortex and spontaneous hypoactivity.


Asunto(s)
Corteza Auditiva/efectos de los fármacos , Salicilato de Sodio/toxicidad , Acúfeno/inducido químicamente , Animales , Corteza Auditiva/fisiopatología , Reacción de Prevención , Conducta Animal , Condicionamiento Psicológico , Masculino , Ratas , Ratas Sprague-Dawley , Reflejo de Sobresalto , Acúfeno/fisiopatología , Acúfeno/psicología
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