Newborn and infant hearing screening for early detection of hearing loss in Nairobi, Kenya.

Background: Early detection of hearing loss and subsequent intervention leads to better speech, language and educational outcomes giving way to improved social economic prospects in adult life. This can be achieved through establishing newborn and infant hearing screening programs. Objective: To determine the prevalence of hearing loss in newborns and infants in Nairobi, Kenya. Methods: A cross-sectional pilot study was conducted at the National hospital and at a sub county hospital immunization clinic. A total of 9,963 babies aged 0-3 years, were enrolled in the hearing screening program through convenient sampling over a period of nine months. A case history was administered followed by Distortion Product Oto-acoustic emissions (DPOAEs) and automated auditory brainstem response (AABR) hearing screening. Results: The screening coverage rate was 98.6% (9963/10,104). The referral rate for the initial screen was 3.6% (356/ 9,963), the return rate for follow-up rescreening was 72% (258 babies out of 356) with a lost to follow-up rate of 28% (98/356). The referral rate of the second screen was 10% (26/258). All the 26 babies referred from the second screen returned for diagnostic hearing evaluation and were confirmed with hearing loss, yielding a prevalence of 3/1000. Conclusions: Establishing universal newborn and infant hearing screening programs is essential for early detection and intervention for hearing loss. Data management and efficient follow-up systems are an integral part of achieving diagnostic confirmation of hearing loss and early intervention.

Hearing Assessment of Free-Ranging Owls and Implications for Wildlife Rehabilitation: 31 Cases (2014-2023).

Owls, members of the avian order Strigiformes, are nocturnal birds of prey that are found worldwide except for Antarctica. Traumatized, free-ranging owls are commonly presented to veterinary hospitals and wildlife rehabilitation facilities with the goal of providing medical care and rehabilitation to enable release back into their natural habitat. Minimal guidelines exist for the release of wildlife, and whereas a need for functional vision is described in raptors, assessing and evaluating hearing is usually not mentioned. This can be problematic for nocturnal predators because hearing is the primary sense utilized by owls when hunting and navigating in their dark environment. The brainstem auditory evoked response (BAER) test is a minimally invasive, objective assessment of hearing commonly used in companion animals. To the authors' knowledge, routine or standardized BAER evaluation has not been reported in traumatized, free-ranging owls. In the following retrospective study, 31 free-ranging owls presented to the University of Georgia Veterinary Teaching Hospital for known or suspected trauma or being found in a debilitated state underwent BAER testing to assess for the presence of complete sensorineural hearing loss. Similar to assessment of hearing in companion animals, the BAER test was elicited using a broad click stimulus delivered at 85 dB nHL. In all owls, qualitative assessment and peak latency measurements of the BAER test reflected hearing ability. This study highlights the importance of hearing in nocturnal raptors, how BAER testing can aid in decision making regarding rehabilitation, and provides a foundation for further investigation of hearing loss in traumatized owls. We suggest that veterinarians working with free-ranging owls in a rehabilitation setting should consider BAER testing as part of routine diagnostic testing.

The use of hearing tests to assess otitis media with effusion in children with Down syndrome.

BACKGROUND: Down syndrome is associated with an increased risk for otitis media with effusion (OME), a childhood condition in which fluid accumulates in the middle ear, potentially leading to hearing loss. The American Academy of Pediatrics Down syndrome guidelines and the American Academy of Otolaryngology - Head and Neck Surgery OME guidelines recommend hearing testing to assess the hearing status of children with Down syndrome diagnosed with OME. METHODS: Through an Institutional Review Board approved retrospective chart review at Children's Mercy, this project assessed how clinical factors affect the frequency in which children with Down syndrome receive hearing testing after diagnosis of OME. The study included data from all children with Down syndrome between 1 and 8 years old diagnosed with OME in the Down syndrome, general pediatrics, and otolaryngology clinics between 2018 and 2020. Demographics and clinical factors, including clinic setting, were collected. RESULTS: Of the 124 patients identified, 91.1 % were diagnosed with OME in the otolaryngology clinic and 33.1 % received hearing testing. While most diagnoses occurred in the otolaryngology clinic, a higher proportion of hearing testing at the time of diagnosis occurred in the Down syndrome clinic. This could be explained by the fact that the Down syndrome clinic is a multidisciplinary clinic, where yearly visits include hearing screening. Bivariate analysis using chi-square or Fisher's tests showed that clinic setting had a significant association (p-value <0.001) with hearing testing. However, logistic regression depicted all clinical factors had an insignificant effect on hearing testing at 5 % significance. CONCLUSION: While results indicate hearing testing is largely not performed to assess OME early in otolaryngology clinics, they may be used to assess intervention efficacy post-diagnosis. Results point to the importance of Down syndrome clinics in early diagnosis of hearing loss leading to timely referrals to otolaryngology clinics which diagnose and manage OME in children with Down syndrome.

[Effect of prenatal glucocorticoid therapy on hearing screening in premature infants].

Objective:To explore the effect of prenatal glucocorticoids therapy on hearing screening in premature infants Methods:Data of 693 preterm infants with gestational age of 24-34+6weeks admitted to theJiangxi Maternal and Child Health Hospital within 24 h after birth from June 2022 to June 2023 were retrospectively analyzed. The infants were divided into the DXM group （544 cases） and the non-DXM group （149 cases） based on whether dexamethasone （DXM） was administered prenatally. General data of preterm infants and parturients in two groups were compared, and the effects of different doses and timing of DXM on hearing screening were analyzed. Results:In the terms of preliminary hearing screening. the pass rate of initial hearing screening in DXM group was significantly higher than that in non-DXM group（53.9% vs 35.6%）, with statistical significance（P<0.05）. Further subgroup analysis showed that the passing rate of preliminary hearing screening in adequate prenatal dose（=4 doses） DXM group（58.1%） was significantly higher than that in insufficient group（48.0%） and excessive group（42.4%）, with statistical significance（P<0.05）. Administering DXM 48 hours to 7 days before birth resulted in a higher pass rate for initial hearing screening compared to administration <48 hours or >7 days before birth （56.4% vs. 48.6%）, with a statistically significant difference （P < 0.05）. In terms of re-hearing screening, the pass rate of secondary hearing screening was not significantly correlated with DXM treatment（P>0.05）, but was significantly correlated with gestational age, birth weight, hospital stays, invasive mechanical ventilation, and common neonatal diseases（bronchopulmonary dysplasia, respiratory distress syndrome）（P<0.05）. Among them, bronchopulmonary dysplasia was an independent risk factor forsecondary hearing screening referral（P<0.05）. Conclusion:A single course of adequate dexamethasone use within 48 h-7 d of prenatal has a positive effect on the preliminary hearing screening of preterm infants.

Newborn Hearing Screening - An Implementation Analysis.

BACKGROUND/AIM: Hearing impairment affects a small but significant percentage of newborns (0.1-0.4%). Newborn hearing screening (NHS) is recommended for early detection and treatment. The implementation of NHS can vary among countries. In this study, we present the methodology, organization, and technical requirements of NHS. This study analyzed results from a tertiary hospital, identified issues, and proposed solutions. PATIENTS AND METHODS: In the studied region, there are five maternity hospitals and a perinatal intensive care center and in 2020, there were 5,864 live births. Screening is performed at three levels. The first screening is conducted on the 2nd-3rd day of a newborn's life in a maternity hospital, the first rescreening on the 3rd-6th week at a relevant ENT department, and the second rescreening on the 3rd-6th month of life at the regional screening center where the central database is also held. RESULTS: In the studied region, 5,793 out of 5,864 (98.79%) newborns received NHS in 2020. Of these, 120 (2.07%) were tested positive on their first screening. Ninety-four patients (78.3%) of those attended the ENT department for a first rescreening. Thirty-four patients (0.59% of total) were tested positive again and referred to the regional screening center. Out of the 27 patients who attended the second rescreening, four (0.07% of the total) were ultimately diagnosed with hearing impairment. CONCLUSION: Our study found that newborn hearing screening (NHS) in our region achieved a high compliance rate of 98.8% for initial screenings in 2020. However, challenges remain in the rescreening process due to data management issues, inter-regional cooperation, and public awareness. The recent implementation of mandatory screenings, updated guidelines, and a centralized database is expected to enhance the effectiveness of NHS. Further research is needed to evaluate these improvements.

Detecting Hearing Loss Through Targeted Surveillance: Risk Registry and Surveillance Timeframe Recommendations.

PURPOSE: The purpose of this study was to inform the revision of a targeted surveillance risk registry by identifying which risk factors predict postnatally identified hearing loss (PNIHL) in children who pass newborn hearing screening and to determine whether hearing surveillance beyond the age of 1 year is warranted. METHOD: We used retrospective analysis of the audiological outcomes of children born in the state of Queensland, Australia, between January 1, 2010, and December 31, 2019, who passed the newborn hearing screen with risk factors. RESULTS: Approximately one third of children were lost to follow-up and could not be included in the analysis. Risk factors that predicted PNIHL in the analyzed cohort were as follows: syndromes associated with hearing loss, craniofacial anomalies, perinatal infections, and family history of permanent childhood hearing loss. Severe asphyxia did not predict PNIHL but yielded some cases of significant bilateral hearing loss. Hearing loss in children with a history of prolonged ventilation was mild and/or unilateral in nature (except in cases where the hearing loss was due to an unrelated etiology). There were no cases of PNIHL in children with hyperbilirubinemia or neonatal bacterial meningitis. For the risk factors that predicted PNIHL, nearly all hearing losses were detected by 1 year of age, except for children with family history where one quarter of hearing losses had a later onset. CONCLUSIONS: The four risk factors recommended for efficient postnatal identification of hearing loss are as follows: syndromes associated with hearing loss, craniofacial anomalies, perinatal infection, and family history of permanent childhood hearing loss. Hearing surveillance through to 1 year old is sufficient except for children with a family history, where a second phase assessment is indicated. Alternative targeted surveillance protocols and models of care are required to minimize loss to follow-up.

Long-term follow-up of otitis media with effusion in neonatal hearing screening.

OBJECTIVES: Increased neonatal referral rate of conductive hearing loss (CHL) related to otitis media with effusion (OME) following universal neonatal hearing screening (UNHS) may cause an unnecessary clinical, emotional, and financial burden. This study analyzes the long-term, audiological, and medical characteristics of CHL associated with OME in neonates in order to establish a standardized protocol following technology-driven improvements in detection and referral rates in UNHS. METHODS: A retrospective study of all neonates with OME-related CHL referred to the University Hospital of Leuven (Belgium) after failing UNHS with the MAICO devices between January 1, 2013 and December 31, 2021 was performed. Follow-up consultations, auditory tests, referral side, birth month, hearing loss degree, underlying pathologies and risk factors, time to normalization, and need for ventilation tubes were assessed. RESULTS: The incidence of CHL related to OME was stable between 2013 and 2021. Of all referred infants with OME, 52.3 % demonstrated spontaneous recovery. The average time to hearing normalization was significantly longer in children with underlying congenital pathologies compared to those without. Moreover, 74.4 % of these children received ventilation tubes compared to 32.0 % of children without underlying pathologies. No correlation was found between the incidence of OME-related CHL with either a hearing loss degree, admission to neonatal intensive care, or history of a nasogastric feeding tube. CONCLUSIONS: In children who failed UNHS due to OME, hearing recovers spontaneously without surgical intervention in 2/3 of the infants without underlying conditions within one year. In children with underlying congenital disorders, the time to hearing recovery is longer and the risk for surgical intervention is higher, underlining the need for implementing a UNHS standardized protocol.

Effects of Natural Delivery and Cesarean Section on the Result of First Hearing Screening of Newborns.

BACKGROUND: Early detection and intervention of hearing issues in newborns are crucial for their auditory and speech development, necessitating newborn hearing screenings. This study aimed to investigate the impact of delivery methods, specifically natural delivery and cesarean section, on newborn hearing screening outcomes. METHODS AND MATERIAL: A retrospective analysis was conducted on data from 600 newborns delivered at The First Affiliated Hospital of Shaoyang University between January 2020 and January 2023. The initial hearing screenings used the AccuScreen otoacoustic emission instrument. The study examined the influence of delivery method on the pass rates of newborns' first hearing screenings within and beyond 48 h postbirth. RESULTS: The pass rates for the initial hearing screenings, conducted within and after 48 h of birth, were significantly higher in the natural delivery group compared to the cesarean section group (P < 0.05). Furthermore, multivariate analysis identified the delivery method as a significant factor influencing the pass rates of newborns' first hearing screenings. CONCLUSIONS: The mode of delivery appears to affect the results of the initial hearing screenings of newborns, though further research is needed to validate these findings.

Impact of national health insurance and socioeconomic disparities on newborn hearing screening performance in South Korea: A nationwide population-based evaluation.

OBJECTIVES: This study aimed to assess the impact of national health insurance coverage on newborn hearing screening (NHS) outcomes by analyzing hearing questionnaires from the National Infant Health Check-up Program (NIHCP) in South Korea. METHODS: This study evaluated the performance and referral rates of NHS using nationwide data from 814,875 infants enrolled in the 4-month NIHCP from January 2017 to December 2019. This period encompasses the periods before and after the National Health Insurance in South Korea began covering NHS expenses in October 2018. The study also investigated household income levels to determine their relationship with participation in the NIHCP and NHS outcomes. RESULTS: The performance of NIHCP increased year-on-year, with NHS performance rates increasing from 88.5 % in 2017 to 91.5 % in 2019. Analysis by household income level revealed that the medical benefit recipients' group had the lowest NHS performance rate of 81.9 % in 2019, whereas that of the higher income level group exceeded 90 %. The NHS referral rate remained consistent at 0.9 % nationally during the study period. CONCLUSION: The inclusion of NHS in national insurance coverage positively influenced its performance rates across South Korea. Nevertheless, the data indicate the need for more focused and customized support for low-income families to enhance early hearing detection and interventions in newborns and infants.

Cochlear implantation in pediatrics: Impact of newborn hearing screening on intervention time.

OBJECTIVES: The newborn hearing screening (NHS) program was globally established for early hearing loss (HL) identification and intervention. Early intervention is essential to minimize or prevent the negative consequences of HL. In Saudi Arabia, the NHS was officially implemented in 2016. Currently, its impact on the timing of cochlear implantations (CIs) in Saudi Arabia remains unclear, and information on potential hospital-related delays affecting early implantation is lacking. Thus, this study aimed to evaluate the effect of implementing the NHS on age at CI in children with prelingual deafness in a CI center in Saudi Arabia, and to evaluate the hospital timing in the CI process. METHODS: All pediatric CI users who presented for the first time to the CI committee (CIC) at a tertiary center and received their implants between 2015 and 2022 were enrolled in this study. Date of birth (DOB), date of presentation to the CI committee (DOCIC), and date of CI surgery (DOCIS) were retrospectively reviewed. RESULTS: In total, 304 CI children were included in the analysis. Approximately 55 % of the children (n = 167) were screened for HL through the NHS, whereas 45 % of the children (n = 137) were born before the launch of the NHS. Both age at the presentation to the CIC (i.e. difference between DOCIC and DOB) and age at implantation (i.e. difference between DOCIS and DOB) were significantly earlier in children who were screened for HL through the NHS than those who were not screened (P < 0.0001). The time difference between the DOCIC and DOCIS was not significantly different between the screened and unscreened children (P > 0.05). CONCLUSION: The implementation of the NHS in the tertiary center has a significant positive effect on age at presentation to the CIC and age at implantation, but not on the actual CI surgery. Further research is needed to reduce the hospital delays before the actual surgery in order to increase the likelihood of children receiving implantation early in their life.

Otolaryngology outcomes of infants with conductive hearing loss identified through universal newborn hearing screening.

OBJECTIVE: Infants and children diagnosed with a conductive hearing loss (CHL) are often referred for otolaryngology assessment. Although this is also a regular occurrence for infants diagnosed with a CHL through Universal Newborn Hearing Screening (UNHS), less is known about these infants and their outcomes. Using a cohort of infants diagnosed with CHL through UNHS and referred to otolaryngology, this study aimed to investigate the relationship between specific demographic or clinical characteristics and 1) triage category 2) middle ear diagnosis and intervention and, 3) service-related factors at otolaryngology. METHODS: Retrospective analysis through clinical chart review was performed on all infants born between January 2014 and December 2017 who referred on UNHS, diagnosed with a CHL and referred to the Queensland Children's Hospital. Descriptive analysis and Chi squared analysis was conducted on data from 95 records. RESULTS: Analysis between all infants referred from UNHS and those who referred, diagnosed with CHL and then referred to otolaryngology suggest that bilateral referrals/medical exclusion, preterm and infants with ≥1 risk factors are more readily associated with referral to otolaryngology for CHL. Nearly all (92.86 %) infants who were referred to otolaryngology had a primary diagnosis of OM and most infants (89.66 %) received grommets as an intervention. The average age of first appointment at otolaryngology was 427 days, the average age of intervention was 579 days and the average occasions of service at otolaryngology was 6.72. CONCLUSION: This paper provides a snapshot into the journey and outcomes of infants referred from UNHS, diagnosed with CHL, and referred to otolaryngology. Further investigation in both general and UNHS populations is needed to better understand and apply these findings.

Standardization of Three Familiar Sound Recognition Tests in Hearing and Deaf Adult Populations.

OBJECTIVE: Recognition of familiar noises is crucial for understanding and reacting appropriately to our auditory environment. Its improvement is one of the benefits expected after cochlear implantation. The aim of this study was to standardize three environmental sounds noise recognition tests and to illustrate their application to a population of deaf adults with cochlear implants. METHOD: Norms were established on a sample of 126 normal-hearing adults divided into 6 age groups. Three familiar sound recognition tests were used: 1) the Blue Mouse "First Familiar Sounds" (BM), 2) the UCL-IRSA test (TI), and 3) the Bernadette Piérart Familiar Sounds Test (TBF). These tests were also administered to 61 implanted deaf ears. RESULTS: We observed a significant effect of age on the accuracy scores of the TI and TBF tests for the hearing group and on the time scores of the TI and BM tests. Overall, the performance of the deaf participants was poorer and more variable than that of the hearing participants. CONCLUSION: We have three tests that can be used in practice to measure the performance of deaf people (with cochlear implants) at different stages of their pre- and post-implant rehabilitation.

Covid-19 infection in pregnant women: Auditory evaluation in infants.

 Recent studies showed that COVID-19 infection can affect cochleo-vestibular system. The possibility of a vertical transmission is controversial. Some studies suggested that it is possible but unlikely, others find no evidence of vertical transmission. The objective of this study was to investigate whether exposure to COVID-19 during pregnancy or at birth has an impact on the hearing of the offspring. As part of the national hearing screening program, we performed in all newborns between January 2022 and February 2023, TEOAEs (Transient Evoked Otoacoustic Emissions) at birth and at 3 months. For those "REFER" at the third month test, we performed aABR (Automatic Auditory Brainstem Response) at 6 months. We analysed separately result between infants born to COVID-positive mothers during pregnancy and those born to COVID-negative mothers. To statistical verify differences we performed "Chi-square test". We enrolled a total of 157 infants, of whom 16 were born to mothers who had a molecular PCR test positive for COVID-19. In the latter we tested a total of 32 ears and only 1 ear (3,1%) resulted "REFER". On the other hand, in the control group we tested a total of 282 ears and 22 (7,8%) were found to be "REFER". Our study showed no significant differences in audiological assessment between newborns exposed to COVID-19 infection during pregnancy or at birth compared to the unexposed group. However, further studies with a larger patient's sample will be necessary for a more comprehensive evaluation.

Availability of resources for paediatric hearing care in a South African province.

BACKGROUND:  Unavailability of healthcare resources can lead to poor patient outcomes. The latter is true for infants with hearing loss and require early hearing detection and intervention (EHDI). AIM:  To determine the availability and distribution of resources for EHDI in state hospitals in the Eastern Cape (EC) province, South Africa. SETTING:  Sixteen state hospitals (nine district, four regional and three tertiary hospitals). METHODS:  Descriptive cross-sectional survey completed between July 2022 and October 2022. RESULTS:  Thirteen hospitals had audiologists (n = 4) or speech therapists and audiologists (n = 9). Specific to equipment, 10 hospitals had a screening otoacoustic emissions or automated auditory brainstem response, 8 hospitals had diagnostic middle ear analysers and only 3 hospitals had diagnostic auditory brainstem response and/or auditory steady state response. Twelve hospitals did not have visual response audiometry (VRA) and 94% had no hearing aid verification systems. Budget allocations were uneven, with only 10 hospitals, i.e., 4 districts, all regional and 2 tertiary hospitals being allocated varying amounts. Subsequently, only 50% provided newborn hearing screening, 56% provided diagnostic evaluations and 14 hospitals fitted hearing aids. CONCLUSION:  Results revealed a limited and uneven distribution of resources, which negatively impacted the provision of EHDI. Even distribution of healthcare resources and further research aimed at strengthening hearing health services is recommended as these could potentially improve equitable access to EHDI and the overall quality of healthcare provided.Contribution: This study highlights the need for even distribution of resources and strengthening of health systems, especially in the dawn of the National Health Insurance.

A call for linguistic and culturally congruent family-centred early hearing detection and intervention programmes in South Africa.

Early Hearing Detection and Intervention (EHDI) programmes are recognised as the standard of care for newborns and infants presenting with hearing impairment, globally. However, widespread implementation of these programmes is far from being realised and faces numerous challenges within the South African context. The United Nations' sustainable development goal 3.8 and South Africa's national development plan seek to achieve equitable access to healthcare service, including EHDI. However, healthcare access is a complex concept which encompasses the dimensions: availability, affordability, acceptability and accommodation in healthcare. South Africa has made great progress towards universal implementation of EHDI programmes. Despite this progress, availability and affordability of these programmes are limited and their acceptability has received limited research focus in this context. Furthermore, accommodation of caregivers, as co-drivers of EHDI programmes and ensuring that EHDI programmes are linguistically and culturally congruent have also been overlooked within the South African context.Contribution: Increased robust efforts in improving access through availability and affordability of EHDI programmes are warranted in South Africa. However, improving access to these programmes through availability and affordability initiatives alone will not result in a pragmatic improvement in their accessibility. Acceptability of these programmes and accommodations such as involving caregivers and family members of children with hearing impairment as equal partners in EHDI programmes and being cognisant of their linguistic and cultural needs must be considered.

The word-with-noise test: test-retest reliability in normal-hearing adults. / Teste de palavras no ruído: confiabilidade no teste-reteste em adultos normo-ouvintes.

PURPOSE: To investigate the reliability of the Word-with-Noise Test in a group of normal-hearing adults. METHODS: Forty-five normal-hearing adult subjects participated in the research. The interval between the first and second assessment was 14 to 28 days, performed during the same time of the day and by the same evaluator. The comparison analysis between the test and the retest was performed considering the general result of the ears, totaling 90 ears evaluated. The inferential analysis included the comparison of the situations in the first and second assessment using the Wilcoxon Test, calculation, and interpretation of the Intraclass Correlation Index. RESULTS: There was a statistically significant difference between the test and retest performances. The intraclass correlation coefficients obtained were indicative of good reliability (r=0.759; p<0.001) for the monosyllabic stimulus and moderate reliability (r=0.631; p<0.001) for the disyllabic stimulus. CONCLUSION: The Word-with-Noise Test demonstrated satisfactory reliability for both the monosyllabic and disyllabic stimuli.

OBJETIVO: Investigar a confiabilidade do Teste de Palavras no Ruído em um grupo de adultos normo-ouvintes. MÉTODO: Participaram da pesquisa 45 sujeitos adultos normo-ouvintes. O intervalo entre a primeira e a segunda avaliação foi de 14 a 28 dias, realizadas no mesmo turno do dia e pelo mesmo avaliador. A análise de comparação entre teste e reteste foi realizada considerando o resultado geral das orelhas, totalizando 90 orelhas avaliadas. A análise inferencial incluiu a comparação das situações na primeira e segunda avaliação por meio do Teste de Wilcoxon, cálculo e interpretação do Índice de Correlação Intraclasse. RESULTADOS: Houve diferença estatisticamente significante entre os desempenhos no teste e reteste. Os coeficientes de correlação intraclasse obtidos foram indicativos de boa confiabilidade (r=0,759; p<0,001) para o estímulo monossilábico e de moderada confiabilidade (r=0,631; p<0,001) para o dissilábico. CONCLUSÃO: O Teste de Palavras no Ruído demonstrou satisfatória confiabilidade tanto para o estímulo monossilábico, quanto para o dissilábico.

Investigation on the contribution of swim bladder to hearing in crucian carp (Carassius carassius).

The swim bladder in some teleost fish functions to transfer the sound energy of acoustic stimuli to the inner ears. This study uses the auditory evoked potential tests, micro-computed tomography scanning, reconstruction, and numerical modeling to assess the contribution of the swim bladder to hearing in crucian carp (Carassius carassius). The auditory evoked potential results show that, at the tested frequency range, the audiogram of fish with an intact swim bladder linearly increases, ranging from 100 to 600 Hz. Over this frequency, the sound pressure thresholds have a local lowest value at 800 Hz. The mean auditory threshold of fish with an intact swim bladder is lower than that of fish with a deflated swim bladder by 0.8-20.7 dB. Furthermore, numerical simulations show that the received pressure of the intact swim bladders occurs at a mean peak frequency of 826 ± 13.6 Hz, and no peak response is found in the deflated swim bladders. The increased sensitivity of reception in sound pressure and acceleration are 34.4 dB re 1 µPa and 40.3 dB re 1 m·s-2 at the natural frequency of swim bladder, respectively. Both electrophysiological measurement and numerical simulation results show that the swim bladder can potentially extend hearing bandwidth and further enhance auditory sensitivity in C. carassius.

Sensitivity of Methods for Diagnosing Noise-Induced Hearing Loss in Cases of Exposures Including Intense Low-Frequency Noise.

Exposure to intense low-frequency sounds, for example inside tanks and armoured vehicles, can lead to noise-induced hearing loss (NIHL) with a variable audiometric pattern, including low- and mid-frequency hearing loss. It is not known how well existing methods for diagnosing NIHL apply in such cases. Here, the audiograms of 68 military personnel (mostly veterans) who had been exposed to intense low-frequency noise (together with other types of noise) and who had low-frequency hearing loss (defined as a pure-tone average loss at 0.25, 0.5 and 1 kHz ≥20 dB) were used to assess the sensitivity of three diagnostic methods: the method of Coles, Lutman and Buffin, denoted CLB, which depends on the identification of a notch or bulge in the audiogram near 4 kHz, and two methods specifically intended for diagnosing NIHL sustained during military service, the rM-NIHL method, which depends on the identification of a notch or bulge in the audiogram near 4 kHz and/or a hearing loss at high frequencies greater than expected from age alone, and the MLP(18) method based on a multi-layer perceptron. The proportion of individuals receiving a positive diagnosis for either or both ears, which provides an approximate measure of sensitivity, was 0.40 for the CLB method, 0.79 for the rM-NIHL method and 1.0 for the MLP(18) method. It is concluded that the MLP(18) method is suitable for diagnosing NIHL sustained during military service whether or not the exposure includes intense low-frequency sounds.

Reduced Channel Interaction Improves Timbre Recognition Under Vocoder Simulation of Cochlear Implant Processing.

OBJECTIVE: This study aimed to investigate the influence of the number of channels and channel interaction on timbre perception in cochlear implant (CI) processing. By utilizing vocoder simulations of CI processing, the effects of different numbers of channels and channel interaction were examined to assess their impact on timbre perception, an essential aspect of music and auditory performance. STUDY DESIGN, SETTING, AND PATIENTS: Fourteen CI recipients, with at least 1 year of CI device use, and two groups (N = 16 and N = 19) of normal hearing (NH) participants completed a timbre recognition (TR) task. NH participants were divided into two groups, with each group being tested on different aspects of the study. The first group underwent testing with varying numbers of channels (8, 12, 16, and 20) to determine an ideal number that closely reflected the TR performance of CI recipients. Subsequently, the second group of NH participants participated in the assessment of channel interaction, utilizing the identified ideal number of 20 channels, with three conditions: low interaction (54 dB/octave), medium interaction (24 dB/octave), and high interaction (12 dB/octave). Statistical analyses, including repeated-measures analysis of variance and pairwise comparisons, were conducted to examine the effects. RESULTS: The number of channels did not demonstrate a statistically significant effect on TR in NH participants ( p > 0.05). However, it was observed that the condition with 20 channels closely resembled the TR performance of CI recipients. In contrast, channel interaction exhibited a significant effect ( p < 0.001) on TR. Both the low interaction (54 dB/octave) and high interaction (12 dB/octave) conditions differed significantly from the actual CI recipients' performance. CONCLUSION: Timbre perception, a complex ability reliant on highly detailed spectral resolution, was not significantly influenced by the number of channels. However, channel interaction emerged as a significant factor affecting timbre perception. The differences observed under different channel interaction conditions suggest potential mechanisms, including reduced spectro-temporal resolution and degraded spectral cues. These findings highlight the importance of considering channel interaction and optimizing CI processing strategies to enhance music perception and overall auditory performance for CI recipients.