Hearing devices such as hearables, personal sound amplification products, hearing aids, and active hearing protectors providing amplification in some settings are increasingly used by individuals with normal hearing. However, the benefits of providing amplification in this population remain unclear. This study investigated the effects of amplification on hearing thresholds, speech intelligibility in quiet, and experienced listening effort in normal-hearing listeners. Forty-four young adults with clinically normal hearing participated in two experiments comparing three conditions: open ear, aided with 0 dB insertion gain to approximate acoustic transparency, and aided with 15 dB flat insertion gain. Amplification was provided using a research hearing aid fitted with closed foam earplugs. Speech intelligibility was assessed with the Oldenburg Sentence Test, and experienced listening effort was measured using Adaptive CAtegorical Listening Effort Scaling (ACALES). Listening through the nominally transparent device introduced consistent disadvantages, including elevated hearing thresholds, reduced speech intelligibility, and increased listening effort. Providing 15 dB of amplification partially compensated hearing threshold elevation, fully restored speech intelligibility and reduced experienced listening effort beyond the unaided condition. Benefits of amplification at low input levels were primarily limited by the equivalent input noise of the hearing-aid microphones. These findings suggest that amplification can provide meaningful benefits for normal-hearing listeners at low speech levels, particularly when listening effort is considered alongside speech intelligibility. Future studies should examine these effects under more ecologically valid listening conditions, and potential benefits of increased amplification in hearing-impaired listeners.
Age-related hearing loss (ARHL) often leads to hearing difficulties, impacting communication and daily functioning even among hearing-aid users. While hearing loss and cognitive functions, such as cognitive shifting ability, have been proposed as predictors of hearing difficulties, their specific contributions remain unclear. This study investigated whether hearing loss and cognitive shifting ability predict self-reported hearing difficulties across the Speech, Spatial, and Qualities of Hearing Scale questionnaire (SSQ) subscales in adults with ARHL who use hearing aids, and whether sex moderates these associations, while controlling for age and level of education. A total of 215 adults underwent audiometry, completed a cognitive flexibility task, and answered the SSQ questionnaire, of which 203 (89 females) were included in our analysis. Hierarchical multiple regression analyses revealed that less hearing loss predicted lower levels of hearing difficulties in the three subscales of the SSQ, and higher education level was a significant predictor of less reported difficulties in the Speech and Spatial subscales. Contrary to our expectations, cognitive shifting ability was not associated with hearing difficulties in any subscale, nor did sex moderate the associations between cognitive shifting ability, degree of hearing loss and hearing difficulties. The findings highlight the influence of hearing loss and education on self-reported hearing difficulties and suggest that cognitive shifting ability does not play a significant role. Future studies should explore other cognitive and demographic factors that might contribute to hearing difficulties in hearing-aid users.
This study evaluated a deep-neural-network denoising system using model-based design, comparing it with adaptive filtering and beamforming across various noise types, SNRs, and hearing-aid fittings. A KEMAR manikin fitted with five audiograms was recorded in reverberant and non-reverberant rooms, yielding 1,152 recordings. Speech intelligibility was estimated using the HASPI from 1,152 KEMAR manikin recordings. Effects of processing strategy and acoustic factors were tested with model-based within-device design that account for repeated recordings per device/program and fitting. Linear mixed model results showed that the DNN with beamforming outperformed conventional processing, with strongest gains at 0 and +5 dB SNR, moderate benefits at -5 dB in low reverberation, and none in medium reverberation. Across SNRs and noise types, the DNN combined with beamforming yielded the highest predicted intelligibility, with benefits attenuated under moderate reverberation. Azimuth effects varied; because estimates were derived from a better-ear metric on manikin recordings. Additionally, this paper reports comparisons using metrics of sound quality, for an intrusive metric (HASQI) and the pMOS non-intrusive metric. Results indicated that model type interacted with processing and acoustic factors. HASQI and pMOS scores increased with SNR and were moderately correlated (r² ≈ 0.479), supporting the use of non-intrusive metrics for large-scale assessment. However, pMOS showed greater variability across hearing aid programs and environments, suggesting non-intrusive models capture processing effects differently than intrusive metrics. These findings highlight the promise and limits of non-intrusive evaluation while emphasizing the benefit of combining deep learning with beamforming to improve intelligibility and quality.
Persons with hearing aids or cochlear implants often have difficulty understanding speech well, especially in noisy environments. Auditory perceptual training can help improve an individual's ability to discriminate and identify sound. The current study aimed to determine the efficacy of the ALICE (Assistant for Listening and Communication Enhancement) program, a self-guided home-based hearing care program including monitoring, training and counseling. A multicentric study was carried out, including hearing aid centers and a cochlear implant center in Flanders (Belgium). Adult participants were randomly assigned to an intervention (n = 65) or a control (n = 65) group. Participants in the intervention group received a tailored flow of exercises that could be streamed to the device or presented in a sound field. All participants were tested before and after 8 weeks using sentences in noise and different self-report questionnaires. Participants in the intervention group were compliant during the 8-week training period. Significant on-task improvements were observed, along with improved speech-in-noise understanding for the intervention group only. The self-report data did not reveal changes following the intervention. Our clinical trial demonstrates that the self-guided ALICE training program is effective at improving the auditory system's ability to parse untrained speech in noise. This enhancement in speech-in-noise performance is specific to the training group, as the control group did not show any improvement. The results of the clinical trial imply that ALICE can be used as a scalable, accessible, and safe hearing care intervention.
Previous studies have shown that older adults can witness a decline in the integration of their spatial auditory cues even when they don't present pathological audiometric thresholds. Nonetheless, when spatial hearing in aging is discussed, most of the focus concerns elderly individuals with hearing impairments or presbycusis, rather than those with clinically normal hearing. In fact, auditory aging (even without presbycusis) may still result in a decline in spatial sensitivity, potentially contributing to the deterioration of key binaural functions crucial for speech understanding, such as binaural summation, squelch effect, and head shadow effect. The current study aims to determine whether Event-Related Potentials (ERPs) can reflect auditory spatial aging in populations without abnormal audiometric thresholds. Using a spatial oddball paradigm, we aim to explore the neural components associated with spatial sensitivity and examine whether these components correlate with changes in binaural integration with age. Our findings suggested a decrease in spatial auditory performance, speech in noise comprehension, and cognitive status across age even when audiometric thresholds were normal. Electroencephalograhy investigation revealed a strong correlation between N100 amplitudes and age, in addition to correlation between unmasking function and N100 amplitudes. These findings underscore the validity of ERP components as markers of spatial hearing performance and aging. This could orient the decision-making concerning the necessity for hearing rehabilitation in some cases to compensate for deficits and prevent auditory aging consequences on peripheral and central auditory processing.
Research into the long-term effects of noise on hearing is often confounded by health and lifestyle differences between individuals. UK police radio ear-pieces are capable of emitting high sound levels and, crucially, are worn in one ear, allowing between-ear comparisons which control for individual-level confounding factors. Low volume-control settings are recommended to reduce risk to police hearing, yet actual usage patterns and auditory effects remain unexamined. This study used a large-scale survey (N = 4,498) to assess ear-piece noise exposure and the associated hearing health. Most participants reported using high volume-control settings and 45.2% reported experiencing signs of temporary threshold shift (TTS) in the exposed ear. Estimated weekly-averaged noise exposures frequently exceeded the UK's 85 dBA Upper Exposure Action Value. Ear-piece use was associated with 73% (95% confidence interval [CI] 46-106%) increased risk of persistent tinnitus, which on mediation analysis appeared to be driven by a subset of users who experienced signs of TTS. Importantly, tinnitus location was associated with the side of exposure, suggesting tinnitus related to device use rather than to other factors. In contrast, Digits-In-Noise thresholds showed no relation with noise exposure; potential explanations include compensatory auditory training effects, but limitations of Digits-In-Noise data must also be considered. Findings highlight a need for further investigation into hearing risks in police personnel, including in-person auditory testing. Risk mitigation strategies might involve improved device design, training on safe use, and expanded hearing health surveillance. Given the potential for cumulative auditory damage, TTS may serve as an early warning sign, warranting attention in broader noise-exposed populations.
Ecological Momentary Assessment (EMA) is a timely method for capturing differences between hearing aids (HAs) or HA features in real-world environments. Studies vary greatly in reporting periods, specifically how long ago an event can have occurred to still be reported and how events are selected when not summarizing over a period of time. The potential effects of different reporting periods on HA or HA feature contrast remain unexplored. In a 14-day EMA study, 22 hearing-aid users assessed both a basic and an advanced HA program, which were switched daily without participant control. Several times daily, participants used a smartphone app to report on satisfaction with the HA program, overall listening experience, sound quality, and listening effort. The app had participants focus on the current situation, denoting a momentary reporting period, and the worst listening experience within the previous 30 min, denoting a short-term retrospective period. Participants also completed an end-of-day questionnaire. Sound-pressure levels and HA classifier data were recorded continuously. Mixed modeling was used to examine the impact of reporting periods on ratings. Main findings showed no rating differences between the two HA programs in momentary or end-of-day assessments. However, differences emerged in short-term retrospective reporting, thus in the assessments of the worst experience within the preceding 30 min. Various time effects were also observed. Depending on the reporting period, the analysis of sound-pressure levels and HA classifier data revealed variations in real-world snapshots. In conclusion, this study underscores the need to diligently define reporting periods in hearing-related EMA research.
Previous research has highlighted challenges for individuals with hearing loss, including increased listening effort and fatigue. This study aimed to: (a) examine the relationship between auditory demand and listening effort, affect, and fatigue, focusing on the moderating role of hearing loss; and (b) assess whether listening effort and affect mediate the effect of auditory demand on fatigue. A total of 130 participants, with and without hearing loss, participated in EMA over 5.5 days, answering questions on listening effort, fatigue, and listening environment attributes. Auditory demand was defined by contextual and subjective components derived from EMA responses. LME models analyzed the effect of auditory demand on listening effort, affect, fatigue and the moderating role of hearing loss. Additional models tested mediation by listening effort and affect. Results: highlighted that both contextual and subjective auditory demand significantly increased listening effort with stronger effects in those with more hearing loss. No effects of contextual auditory demand on affective state were observed, nor was there a moderation effect of hearing loss. An effect of subjective auditory demand on affect was observed, but no moderation of hearing loss was present. Contextual and subjective auditory demand predicted fatigue (β = 0.07-0.14, p < .01-p < .001) with amplified effects present in those with more hearing loss (pinteraction < .01) for contextual demand. Mediation analyses highlighted that listening effort contributed to the demand-fatigue relationship, though patterns differed by demand type. The results indicate that increased listening effort, rather than negative affect, may underlie the association between auditory demand and fatigue.
In birds, detection of sound source azimuth begins in the nucleus laminaris (NL), which computes interaural time differences (ITDs). Inhibition has been proposed to protect NL neurons from losing ITD sensitivity with increasing sound level, although the nature of this inhibition is incompletely understood. Anatomical studies show GABAergic synapses throughout NL and first order nuclei, while in vitro studies in chicken NL showed that GABAergic inhibitory postsynaptic potentials (IPSPs) shorten membrane time constants, perhaps to allow the membrane potential to follow rapid synaptic currents accurately over a range of sound levels. Given the importance of inhibition in regulating auditory brainstem activity, we examined the nature of inhibitory input to NL in vivo. The Superior Olivary Nucleus (SON) is the major source of descending GABAergic inhibition to the ipsilateral nucleus magnocellularis (NM), nucleus angularis (NA) and NL, and receives excitatory input from NA and NL. We used viral tracers to reveal projections from SON to NL, and characterized response types within SON. In NL, we isolated inhibitory synaptic contributions from extracellular field potentials through the iontophoretic application of blockers of GABA (gabazine) or glycine (strychnine). These blockers increase onset and offset responses evoked by tonal stimuli, but did not shift best ITD. The co-application of gabazine and strychnine revealed supra-linear summation of GABA and glycine. Profiles of synaptic activation revealed more prominent inhibition following stimulus offset, suggesting inputs to NL originate from both sustained and offset response types of the SON. These heterogeneous responses may represent separate SON neuronal populations. Together, our results support the role of SON inhibition in increasing the dynamic range of ITD tuning of NL neurons.
Individuals with hearing loss, even when using hearing aids, often perceive pleasant environmental sounds as less pleasant than do those with normal hearing. This bias in emotional response may negatively impact well-being, leading to decreased social participation and increased loneliness. The present study examined whether the Positive Focus intervention-encouraging hearing aid users to focus on positive listening experiences-could influence emotional response to environmental sounds. Thirty participants were randomly assigned to either a Positive Focus or a Control group. At the initial laboratory visit, all participants were fitted with study hearing aids and performed affective ratings of 120 environmental sounds. Over 3 weeks, both groups wore the hearing aids; the Positive Focus group additionally reported daily positive listening experiences via a text message. At the end of the three-week period, participants completed questionnaires on hearing aid outcomes and repeated the affective ratings. The Positive Focus intervention did not alter emotional responses to environmental sounds in a laboratory setting. However, regression analyses revealed that valence ratings of typically pleasant sounds moderated the effectiveness of Positive Focus on hearing aid benefit; the intervention was more effective for individuals less naturally inclined to respond positively to such sounds. These findings suggest that valence screening may help identify individuals most likely to benefit from Positive Focus, supporting more personalized hearing care strategies.
Difficulty recognizing speech in noise is a common complaint among those with sensorineural hearing loss. Yet the degree of difficulty differs widely among individuals, often unrelated to the clinical gold standard for evaluating hearing, the pure-tone audiogram. Research has isolated both auditory and nonauditory factors responsible for these differences, but these factors do not operate in isolation. In the present work, a generic computational model involving simultaneous cue sensitivity, cue reliance, and decision noise provided an integrative framework for identifying sources of between-listener variance not accounted for by the audiogram. The framework was applied to performance differences within and between normal-hearing (NH) and hearing-impaired (HI) groups in the processing of linguistic, acoustic, and statistical cues supporting speech recognition in noise. The primary source of performance differences between groups was differences in sensitivity for the subtle, but largely stationary acoustic cues required for speech recognition. The overwhelming source of performance differences within groups was differences in decision noise associated with more salient, but highly variable statistical cues for speech separation. For speech separation, HI listeners placed far greater reliance than NH listeners on the one cue for which they were most sensitive. HI listeners, but not NH listeners, benefitted by shifting all acoustic information to this most relied on cue. The results provide preliminary support for the feasibility of integrative modeling as a means of evaluating the collective influence of factors affecting speech recognition in noise.
Hearing aids, which are primarily designed to improve the intelligibility of speech, can negatively affect the perception and enjoyment of music. This large-scale survey study, conducted between 2016 and 2018, explored hearing aid use and preference behavior in both recorded and live music listening settings, aiming to understand the challenges and strategies used by listeners to improve their experiences, and how these may be affected by level of hearing loss (HL). One thousand five hundred and seven hearing aid users (mean age = 60 years) completed an online survey about their music listening behavior and use of hearing aids. Results showed that whilst hearing aids support engagement in music listening, they also present many issues and overall helpfulness is mixed. The most commonly reported issue was distortion and poor sound quality, particularly in loud or live contexts. The most frequently reported strategy for reducing distortion was to remove hearing aids altogether. Only a third of the sample reported using a music program and effectiveness was mixed, suggesting that manufacturer music programs do not currently provide significant benefits for music listening, and further research into the use, uptake and efficacy of music programs is needed. We call for further research into signal processing strategies for music especially for high sound levels such as live music or concert settings. The positive impact of mindsets supporting proactive behaviors, perseverance, adaptation, and experimentation with different technologies, genres, and listening environments was highlighted, strengthening the evidence base for audiologists to provide music listening guidance in the clinic.
Previous research has demonstrated that remote testing of suprathreshold auditory function using distributed technologies can produce results that closely match those obtained in laboratory settings with specialized, calibrated equipment. This work has facilitated the validation of various behavioral measures in remote settings that provide valuable insights into auditory function. In the current study, we sought to address whether a broad battery of auditory assessments could explain variance in self-report of hearing handicap. To address this, we used a portable psychophysics assessment tool along with an online recruitment tool (Prolific) to collect auditory task data from participants with (n = 84) and without (n = 108) self-reported hearing difficulty. Results indicate several measures of auditory processing differentiate participants with and without self-reported hearing difficulty. In addition, we report the factor structure of the test battery to clarify the underlying constructs and the extent to which they individually or jointly inform hearing function. Relationships between measures of auditory processing were found to be largely consistent with a hypothesized construct model that guided task selection. Overall, this study advances our understanding of the relationship between auditory and cognitive processing in those with and without subjective hearing difficulty. More broadly, these results indicate promise that these measures can be used in larger scale research studies in remote settings and have potential to contribute to telehealth approaches to better address people's hearing needs.
The purpose of this study was to evaluate the effect of sound quality on ratings of mood (esteem-related affect, vigor, and fatigue), listening-related fatigue, and perceived hearing-related experiences (speech intelligibility, perceived disability, participation, concentration). Thirty adults (51-80 years old) with bilateral hearing loss and at least six months of hearing aid experience participated in this crossover study. They adjusted hearing aids based on sound quality in a laboratory setting, creating a preferred program (good sound quality) and a non-preferred program (tolerable sound quality). After a cooling-off period, they wore each hearing aid program (counterbalanced) home for approximately one week each. During the home trial, they provided ratings of hearing aid sound quality, mood, and hearing-related experiences daily. After each home trial, they rated their listening-related fatigue retrospectively. Sound quality ratings were significantly related to hearing-related experiences and mood ratings during the home trial. Nineteen of the participants preferred their "good" program during the home trial, while the remaining 11 preferred the "tolerable" program. For the participants whose program preference was consistent between the lab and home experiences, listening-related fatigue and mood were significantly better during the week with the "good" program. These results highlight the importance of sound quality for listening-related fatigue and mood for adult hearing aid users.
Deep neural network (DNN)-based noise reduction has emerged as a promising advancement in hearing aid signal processing as a means to improve speech intelligibility in noisy environments for hearing aid wearers. The aim of this study was to investigate the impact of the DNN on speech intelligibility in speech-shaped noise (SSN) and multitalker babble (MTB) when the target speech was coming from the front and from the side. Subjective ratings of clarity, total impression, listening effort, and background noise awareness were also collected. Twenty adult participants with mild to moderately severe sensorineural hearing loss were fitted with hearing aids from a single manufacturer, programmed with four different settings that varied across combinations of microphone directionality (omnidirectional and directional beamforming) and noise reduction (off, traditional, DNN). Results showed that DNN, when combined with beamforming, consistently outperformed the other programs across all metrics. Outcomes were influenced by both noise type and spatial configuration. DNN was more effective in SSN than MTB. Beamforming was especially beneficial when the target speech came from the front. Listening in programs that included both DNN and beamforming together resulted in additional benefits shown in the outcome measures, most likely due to the beamforming improving the signal-to-noise ratio and providing a cleaner signal for the DNN to work with.
Music is central to many people's lives, and hearing loss (HL) is often a barrier to musical engagement. Hearing aids (HAs) help, but their efficacy in improving speech does not consistently translate to music. This research evaluated systems submitted to the 1st Cadenza Machine Learning Challenge, where entrants aimed to improve music audio quality for HA users through source separation and remixing. The HA users (N = 53, ranging from "mild" to "moderately severe" HL) assessed eight challenge systems (including one baseline using the HDemucs source separation algorithm, remixing to original mixes of music samples, and applying National Acoustic Laboratories Revised amplification) and rated 200 music samples processed for their HL. Participants rated samples on basic audio quality, clarity, harshness, distortion, frequency balance, and liking. Results suggest no entrant system surpassed the baseline for audio quality, although differences emerged in system efficacy across HL severities. Clarity and distortion ratings were most predictive of audio quality. Finally, some systems produced signals with higher objective loudness, spectral flux and clipping with increasing HL severity; these received lower audio quality ratings by listeners with moderately severe HL. Findings highlight how music enhancement requires varied solutions and tests across a range of HL severities. This challenge provided a first application of source separation to music listening with HL. However, state-of-the-art source separation algorithms limited the diversity of entrant solutions, resulting in no improvements over the baseline; to promote development of innovative processing strategies, future work should increase complexity of music listening scenarios to be addressed through source separation.
Implicit learning is thought to play an important role in speech recognition under challenging conditions. However, auditory deprivation has been proposed to influence implicit learning, including in the visual modality, although evidence in adults with post-lingual deafness is limited. Therefore, we investigated implicit visual learning and its associations with speech recognition in adults with post-lingual deafness who use cochlear implants (CIs). Thus, this study focuses on the effects of late auditory deprivation rather than on the effects of early deprivation associated with congenital deafness. Adult CI users (n = 30) and a group of individuals with normal hearing (NH, n = 36) completed two implicit visual learning tasks (statistical and perceptual), a battery of challenging speech recognition tests and cognitive measures (vocabulary, working memory, attention, and verbal processing speed). NH listeners demonstrated significant visual statistical learning, whereas CI users showed a similar but nonsignificant pattern. In the visual perceptual learning task, both groups exhibited comparable learning effects. In CI users, visual statistical learning contributed to the recognition of speech in noise (words and sentences). Visual perceptual learning only contributed to the recognition of words in noise. The current findings are inconsistent with the idea that auditory deprivation beyond the sensitive period interferes with visual learning. Rather, in CI users, visual implicit learning contributes to the recognition of challenging speech. Therefore, future work might investigate whether visual learning in CI candidates is predictive of postimplantation milestones.
The discrepancy between the hearing aid benefit estimated in standard audiological tests, like speech audiometry, and the perceived benefit in daily life has led to interest in methods better reflecting real-world performance. In contrast to audiological tests, everyday communication commonly takes place in enclosed spaces with acoustic reflections and multiple sound sources, including sounds from adjoining rooms through open doors. This study investigates speech recognition thresholds (SRTs) with a sentence test in a laboratory environment resembling an average German living room with an adjacent kitchen. Additionally, acoustic simulations of the environment were presented in a large-scale (86) and small-scale (4) loudspeaker array, with the latter feasible for a clinical context. Measurements with normal-hearing and hearing-impaired listeners were conducted using different spatial target positions and a fixed masker position. One of the target positions was within the adjacent kitchen without line-of-sight to the sound source, representing a challenging acoustic configuration. Hearing-impaired listeners performed the measurements with and without their hearing aids. SRTs were compared between different presentation settings and to those measured in standard free-field audiological spatial configurations (S0N0, S0N90). An auditory model was employed for further analysis. Results show that SRTs in the simulated living room environment with 86 and 4 loudspeakers matched the real environment, even for aided listeners, indicating that virtual acoustics representations can reflect real-world listening performance. When signal-to-noise ratios were normalized, the measured hearing aid benefit did not differ significantly between the standard audiological spatial configuration S0N90 and any spatial configuration in the living room environment.
Hearing-related quality of life is a crucial outcome for adults with cochlear implants. The Cochlear Implant Quality of Life (CIQOL)-35 Profile is a patient-reported outcome measure originally developed in English. In a previous study, this instrument was cross-culturally adapted into German to address the need for standardized assessment tools in German-speaking regions. To ensure the adapted instrument meets psychometric criteria, validation is required. The German adaptation of the CIQOL-35 Profile was validated through an online survey including questions on demographics, the German CIQOL-35 Profile, and the German Nijmegen Cochlear Implant Questionnaire (NCIQ). The collected data were analyzed for reliability and validity. A total of 204 adults (aged 19-87 years) with bilateral hearing loss completed the online survey. Cronbach's α between 0.84 and 0.91 demonstrates good internal consistency for all subscales of the CIQOL-35 Profile and the global outcome. Moderate to strong correlations (rs = 0.55-0.85) between the CIQOL and NCIQ indicate good convergent validity. Confirmatory factor analysis established construct validity for the German CIQOL instruments. These findings confirm that the adapted German version of the CIQOL instruments is a reliable and valid measure for assessing hearing-related quality of life in adults with cochlear implants and demonstrates higher validity than the NCIQ. The availability of the CIQOL in multiple languages facilitates international comparability of research results and increases clinical application. Implementing quality of life instruments in clinical practice enables a more comprehensive evaluation of patient outcomes and may help identify patient needs that may be addressed in therapy and rehabilitation.
SLC26A4 is a major causative gene for hereditary hearing loss, its mutation spectrum shows pronounced population specificity. In Chinese populations, patients predominantly carry biallelic mutations, and compound heterozygous genotypes are prevalent, which results in a wide spectrum of auditory phenotypes. However, how different alleles interact within these contexts to shape phenotypic variability remains poorly understood. We employed cellular and mouse models to explore the allele-specific mechanisms associated with two novel mutations, a frameshift mutation and a missense mutation, in compound heterozygous that share the same splice-site pathogenic allele. In vitro, wild-type (WT) and mutant (c.574delC, c.1211C>A) SLC26A4 constructs were expressed in HeLa cells to assess pendrin localization. Both mutations reduced membrane enrichment and increased intracellular retention. In vivo, compound heterozygous knock-in mouse models (Slc26a4c.574delC/c.919-2A>G and Slc26a4c.1211C>A/c.919-2A>G) were generated using CRISPR/Cas9. The auditory function and cochlear pathology were investigated. Both compound mutants exhibited elevated ABR thresholds, with more severe hearing loss in Slc26a4c.574delC/c.919-2A>G mice. Correspondingly, these mice showed marked hair cell disruption, stereociliary loss, and cochlear structural abnormalities, whereas the Slc26a4c.1211C>A/c.919-2A>G mice displayed milder changes. Transcriptomic profiling examined by bulk RNA-sequencing revealed broader differential expression in Slc26a4c.574delC/c.919-2A>G mice, enriched in structural and developmental pathways, while the missense model showed predominantly immune-related signatures. Our findings demonstrate that allele-specific functional divergence in compound heterozygous SLC26A4 mutations leads to distinct auditory dysfunction, cochlear pathology, and transcriptional programs. These findings provide mechanistic insight into the phenotypic heterogeneity of hearing loss and may indicate future allele-specific interventions or therapeutic strategies.