The digits-in-noise (DIN) test is a validated tool for assessing speech reception thresholds in noise and is widely used in hearing screening. The diotic DIN condition presents identical digits and noise to both ears, whereas the antiphasic condition uses phase-inverted digits, which may enhance sensitivity to specific types of hearing loss. This study aimed to evaluate whether the antiphasic DIN condition better predicts various types of hearing loss than the diotic condition, with a particular focus on its value in identifying patterns suggestive of noise-induced hearing loss in adolescents. This was a cross-sectional study conducted among 2851 adolescents aged 16 to 22 years participating in a population-based cohort study. All participants underwent pure-tone audiometry, tympanometry, and both diotic and antiphasic DIN tests. Hearing loss was categorized based on audiometric criteria into unilateral or bilateral sensorineural hearing loss (SNHL), conductive hearing loss, notched audiograms, and high-frequency hearing loss (HFHL). Logistic regression models were used to examine associations between DIN outcomes and hearing loss categories. Receiver operating characteristic curve analyses were conducted to assess the discriminative ability of the diotic and antiphasic conditions. Mean DIN speech reception thresholds were -9.0 dB for the diotic condition and -16.1 dB for the antiphasic condition. The antiphasic condition showed stronger correlations with audiometric thresholds and steeper regression slopes, indicating greater sensitivity to hearing loss. It more accurately predicted unilateral SNHL (odds ratio [OR] = 2.48 versus 1.34 for diotic) and conductive hearing loss (OR = 3.42 versus 2.07). Although there was an association with notched audiograms (OR = 1.09), the discriminative ability of the antiphasic condition for detecting this pattern was low (area under the curve [AUC] = 0.515). Predictive values for HFHL were comparable between the two conditions (OR = 1.23 antiphasic versus 1.60 diotic). Overall, the antiphasic DIN condition showed a higher AUC (0.789) for detecting any hearing loss than the diotic condition (0.613). Both DIN conditions were associated with hearing loss, but the antiphasic condition demonstrated superior sensitivity, particularly for detecting unilateral SNHL and conductive hearing loss. Its association with notched audiograms was statistically significant, yet the low discriminative value limits its practical use in screening for noise-induced hearing loss. For HFHL, both DIN conditions performed similarly, possibly due to the mild degree of hearing loss in most cases. These findings support the use of the antiphasic DIN condition as a more effective screening tool for specific types of hearing loss in adolescents, though its utility for identifying early signs of noise-induced damage remains limited.

Auditory brainstem responses (ABRs) are used to diagnose hearing loss across multiple frequencies in infants and others who cannot participate in behavioral testing. The parallel ABR (pABR) paradigm measures response waveforms to all frequencies from 500 to 8000 Hz in both ears simultaneously, rather than serially in one ear at a time. Work so far has been conducted with air-conducted stimuli through insert earphones, but bone-conducted stimuli are also an essential part of diagnosing the type of hearing loss by determining the relative contributions of conductive and sensorineural hearing loss. This study aimed to confirm the feasibility of bone-conduction pABR. We recruited a cohort of young adults with normal hearing. An intensity series of two-channel ABRs was measured to pABR stimuli played through ER-2 insert earphones, as well as with a B-81 bone vibrator with contralateral masking. Behavioral thresholds were also measured to compare dB nHL correction factors. To keep sessions under 3.5 hr only one ear was tested with bone conduction. The ear with bone conduction and the order of transducers were counterbalanced across participants. Waveform morphologies for each transducer were compared by their residual noise and their wave V latencies and amplitudes. For the same dB nHL levels, responses to both transducers aligned well, and wave V amplitudes and latencies were similar. While stimulus artifacts can be an issue with bone conduction, the steps taken to mitigate them in air conduction pABR were also effective for bone conduction: clear bone-conducted responses were measured, and residual noise was similar for both transducers. Bone-conducted responses to 8 kHz were weak, which was not surprising given the physics of bone conduction and the output capabilities of the bone vibrator. As expected, behavioral thresholds were higher for pABR than pure-tone stimuli, and by the same offset for both transducers. The dB nHL values differed due to the difference in reference equivalent threshold levels for inserts and the bone vibrator. Air and bone conduction provided similar waveforms, indicating that bone-conduction pABR is feasible. Together with establishing dB nHL values, this work represents an important step toward translating the pABR for diagnosing all types of hearing loss.

To determine how cochlear nerve degeneration (CND) relates to tinnitus and sound hypersensitivity in normal-hearing listeners, and whether these symptoms are associated with distinct patterns of central gain within the auditory brainstem. In a cohort of normal-hearing adults with normal audiometric thresholds (≤20 dB HL from 0.25 to 8 kHz) and mean extended high-frequency thresholds ≤20 dB HL, we recorded click-evoked electrocochleography (ECochG) and assessed sound sensitivity using the Hyperacusis Handicap Questionnaire (HHQ). To separate peripheral from central contributions, we used a frequency-based filtering approach that exploits differences in the temporal properties of auditory generators along the ascending pathway, applying a high-frequency filter (470 to 3000 Hz) to derive peripheral auditory nerve measures and a low-frequency filter (3.3 to 470 Hz) to isolate slower brainstem components. Mixed-effects and sequential regression analyses were used to examine associations between ECochG markers, tinnitus status, and HHQ scores. High-pass ECochG responses showed that both tinnitus and elevated HHQ scores were independently associated with reduced peripheral amplitudes, consistent with CND. In high-pass waveforms, cochlear nucleus gain was selectively elevated in participants with tinnitus, regardless of HHQ score. In contrast, low-pass responses revealed that a later brainstem component, and its amplitude relative to the earlier component, were increased in participants with high HHQ scores, independent of tinnitus status. Sequential regression analyses indicated that the effects of peripheral neural loss on tinnitus and on sound sensitivity overlapped only partially, with each symptom not fully accounting for the other. In normal-hearing listeners, tinnitus and hyperacusis share a common peripheral correlate in CND but exhibit distinct brainstem gain signatures. These findings suggest that tinnitus and sound hypersensitivity reflect dissociable forms of central compensation to cochlear nerve injury.

Behavioral measurements of auditory masking have been fundamental in developing models of hearing. However, their clinical utility-their feasibility and usefulness in routine patient assessment-is limited because they are attention-dependent and rely on active participation. Moreover, the behavioral masking paradigm requires a large number of stimulus combinations (multiple masker and probe configurations) and can be time-consuming for participants compared to standard audiometry. Auditory steady-state responses (ASSRs) provide an objective alternative and are already widely used to estimate auditory thresholds in quiet. Unlike behavioral methods, ASSRs can be recorded from individuals who cannot provide reliable behavioral responses, such as infants or patients with cognitive or communication difficulties. However, the relationship between ASSRs and behavioral masking thresholds remains unclear. This study investigated how spectral masking affects ASSRs and how these effects relate to behavioral masking thresholds. We hypothesized that, when probes are presented at equal levels above individual behavioral masking thresholds, the resulting ASSR masking effect would remain constant, regardless of probe frequency or masker level. This study examined masking effects on ASSRs in 25 normal-hearing adults. Behavioral masking thresholds were first obtained using a low-pass noise masker with a 707 Hz cutoff presented at 65 and 85 dB SPL. Probe signals were one-third-octave-wide noise centered at 891 and 1414 Hz. ASSRs were then recorded to 40-Hz amplitude-modulated probes presented at 20 and 30 dB above individual behavioral masking thresholds. ASSRs were recorded in both masker-present and masker-absent conditions, using scalp- and ear-EEG. ASSR amplitudes were compared across conditions using permutation tests and linear mixed-effects modeling. ASSR amplitudes were consistently reduced in masker-present compared to masker-absent conditions, confirming that the presence of the masker affects electrophysiological responses. However, the magnitude of the masking effect varied with experimental parameters. At 65 dB SPL, ASSR amplitudes remained relatively stable across probe frequencies, whereas at 85 dB SPL, amplitudes at 1414 Hz were significantly lower than at 891 Hz across all recording configurations. Contrary to our hypothesis, equal probe levels relative to the behavioral masking thresholds did not yield constant masking effects. The data support a model in which electrophysiological responses integrate activity across multiple auditory filters, whereas behavioral detection is dominated by the internal filter with the highest signal to noise ratio. ASSRs are systematically influenced by spectral masking, with effects depending on masker intensity, probe frequency, and presentation level. Results of the study demonstrate that ASSRs can be used to probe auditory masking and highlight ASSR's potential as an objective tool for assessing individual masking thresholds.

Listening effort and listening-related fatigue are clinically important yet rarely assessed in routine audiology. This study culturally adapted the Effort Assessment Scale (EAS) into Chinese and psychometrically evaluated the Chinese EAS (C-EAS) and the 10-item Vanderbilt Fatigue Scale for Adults-10 (C-VFS-A-10) in Chinese-speaking adults. Associations with better-ear pure-tone average (PTA), tinnitus, and key demographic factors were also examined. A two-phase study was conducted. Phase 1 followed established guidelines to translate and culturally adapt the EAS. Phase 2 was a cross-sectional validation in 701 adults recruited from a tertiary hospital in China (normal hearing, n = 180; unilateral hearing loss, n = 22; bilateral hearing loss, n = 499). A subsample of 85 participants with hearing loss completed repeat testing over 7 to 21 days to assess test-retest reliability. All participants completed the C-EAS, C-VFS-A-10, the Hearing Handicap Inventory for the Elderly/Adults-Screening version (HHIE/A-S), and pure-tone audiometry. Psychometric evaluation included internal consistency, test-retest reliability, factor analyses, convergent validity with PTA and HHIE/A-S, and item response theory (IRT) modeling, alongside ANCOVA and multivariable regression. Both scales showed excellent internal consistency and high short-interval stability. Scale-specific confirmatory factor analyses supported essential unidimensionality adequate for total-score use. Convergent validity was supported by moderate associations with better-ear PTA and HHIE/A-S (ρ = 0.47 to 0.63). Item-level diagnostics indicated localized local dependence for both instruments. For the C-EAS, item-level IRT parameter estimates were unstable under local dependence, supporting the use of summed total scores. For the C-VFS-A-10, a graded-response testlet model produced stable item parameters and high measurement precision across the range where most respondents fell. Scores on both measures increased with hearing-loss severity. In multivariable models, higher better-ear PTA and tinnitus independently predicted higher effort and fatigue scores, while age showed a small additional association with effort only. The C-EAS and C-VFS-A-10 are reliable, culturally adapted measures of listening effort and listening-related fatigue for Chinese-speaking adults. Associations with better-ear PTA and tinnitus support clinical relevance.

Complex stimuli such as two-tone stimuli (f1 and f2) elicit frequency-following responses that reflect phase-locking to the stimulus envelope (f2 - f1) and temporal fine structure at multiple stages of the auditory pathway, from the cochlea to the cortex. The relative contribution of these structures to the scalp-recorded envelope-following response (EFR) remains a matter of debate. Although subcortical sources have been proposed as the main contributors, near-field recordings close to the cochlea contain pre-neural components and have recently been reported in auditory steady-state responses (ASSRs), a version of the EFR used to measure thresholds at the four frequencies (0.5, 1, 2, 4 kHz) most relevant for objective audiogram estimations. The present study evaluated the EFR in 26 auditory neuropathy spectrum disorder (ANSD) cases and 79 children with normal electrophysiological thresholds and distortion product otoacoustic emissions (controls). In addition, this study presents data from a battery of auditory neurophysiological objective tests applied to the 26 ANSD cases. EFRs were recorded using horizontal (EFR-H) and vertical (EFR-V) channels and the generalized primary tone phase variation method, allowing isolation of the EFR waveforms in the time domain to obtain direct latency and phase-locking value (PLV) measurements. EFRs detected in ANSD cases were compared with those of the controls. The standard audiological objective tests included tympanograms, distortion product otoacoustic emissions, click-evoked auditory brainstem responses (ABRs), and ASSRs. EFR-H was detected in five ANSD cases, showing shorter onset latencies, shorter response durations, and lower PLVs than controls. Lower PLVs were also observed in the EFR-H from the contralateral ears of unilateral ANSD cases. The EFR-V was undetected in all ANSD patients except for two, who showed milder neural desynchronization in their click-evoked ABRs and exhibited the lowest ABR thresholds within the ANSD cases. In 15 ANSD cases, with totally absent neural click-evoked ABRs, ASSRs were detected for at least one tested frequency, indicating a discrepancy between ABR and ASSR-estimated thresholds. The EFR-H observations suggested a pre-neural origin, with the asymmetrical mechanoelectrical transduction process at the sensory hair cells as the main contributor. These findings provide further evidence of a pre-neural potential explaining the discrepancy between ABR and ASSR threshold estimations in ANSD. In addition, the results from the contralateral ears of unilateral ANSD cases may reveal subtle deficits typically undetected by standard audiological techniques. Overall, the study of noninvasive EFR recordings in ANSD may contribute to refining their diagnosis, ultimately improving their treatment.

There remain large variations in cochlear implant auditory-speech perception ability, which are poorly explained by patient history factors. This study aims to better understand how combinations of speech processing limitations, identified using psychophysical and functional brain imaging measures, are associated with long-term speech understanding outcomes of new cochlear implant recipients. Forty-three cochlear implant recipients (44 ears) were recruited to participate in a longitudinal study to evaluate limitations at various locations along the auditory processing pathway. At the periphery, intra-cochlear neural health was estimated using focused psychophysical thresholds. Higher-order across-electrode intensity discrimination ability was assessed using psychophysical "spectral tilt." At the cortical level, cross-modal activation of the auditory cortex was assessed using functional near-infrared spectroscopy. Speech understanding outcomes were evaluated in competing multi-talker babble noise at 1-year post-device switch-on. We found that greater abilities to discriminate smaller across-electrode stimulation intensities ( R2 = 0.138, p = 0.047) and smaller cross-modal activations of the auditory cortex ( R2 = 0.216, p = 0.01) were significantly associated with better speech understanding outcomes in cochlear implant recipients. Furthermore, both measures contributed significantly to better predict speech understanding outcomes in a multiple regression model (Adj R2 = 0.312, p = 0.009). The results suggest that recipient-specific psychophysical and functional brain imaging metrics contribute significantly toward individual differences in speech understanding outcomes. Different recipients can be affected by different limitations, which can be identified using these tests, and therefore lead to potential patient-specific methods to improve their speech understanding.

The pupil dilation response is often used as a physiological measure of listening effort. One way to manipulate listening effort is to manipulate intelligibility. Only a few studies assessed the relationship between intelligibility and the pupil dilation response in cochlear implant (CI) users. Those studies did not consistently replicate the effects of intelligibility on the pupil dilation response evoked by sentence recognition in noise as observed in individuals with typical hearing or hard of hearing. Therefore, this study examined the effects of intelligibility on the pupil dilation response in CI users using several types of speech material. The type of masker is also known to influence listening effort as measured by pupillometry in individuals with typical hearing and hard of hearing. To our knowledge, this is not yet investigated in CI users. Therefore, this was also assessed in the current study. Finally, to account for subjective experiences, ratings of listening effort, difficulty, performance, and tendency of giving up were assessed. Twenty-eight postlingually deafened adult unilateral or bimodal CI users participated. Their ages ranged from 41 to 71 yrs old (mean = 58.4). A 3 × 3 within-subjects design was used with 3 intelligibility conditions (quiet, 50%, and 20% intelligibility in continuous noise) and 3 types of speech material (digit triplets, consonant-vowel-consonant [CVC] words, everyday sentences). Linear mixed model analyses assessed the effects of speech material and intelligibility condition on the mean pupil dilation (MPD), peak pupil dilation (PPD), and baseline pupil size (BPS). A paired sample t test was used to compare the effect of masker type (continuous noise versus a single interfering speaker) on these pupil measures for 50% sentence intelligibility. For all conditions, participants rated their experienced listening effort, difficulty, performance, and tendency of giving up. In the main analysis (N = 23), MPD, PPD, and BPS differed between the speech materials, but these measures did not depend on speech intelligibility. CVC words elicited the lowest MPDs and PPDs, followed by digit triplets and everyday sentences, with the latter showing the most pronounced pupil responses. The BPS was larger for sentences compared with CVC words and digit triplets. CVC words and sentences were rated as the most effortful and difficult, with the lowest self-perceived performance, and evoking the highest tendency to give up. Self-perceived performance was furthermore influenced by intelligibility (quiet > 50% > 20%). The other subjective ratings, such as listening effort, decreased with increasing intelligibility. A separate analysis on the data for the digit triplet material, including all CI users (n = 28), showed an intelligibility effect on the PPD. Finally, the analysis (N = 15) of the effect of masker type showed that PPDs and BPSs were larger for sentences masked with an interfering speaker compared with continuous noise. The intelligibility conditions in this study did not result in any measurable differences in listening effort, as indicated by the pupil dilation responses of unilateral or bimodal postlingually deafened CI users for everyday sentences or CVC words. A main effect of intelligibility condition on PPD was only found for digit triplets. Speculatively, this may be because the relative simplicity and low cognitive load evoked by this speech material allowed intelligibility effects to become apparent in this specific group of listeners. Subjective ratings indicated greater listening effort, difficulty, and a tendency to give up at lower intelligibility levels. When sentences were masked with an interfering speaker, both PPD and subjective listening effort increased compared with masking with continuous noise. These findings suggest that manipulating masker type can alter the pupil dilation response and perceived listening effort in CI users, even when using everyday sentences.

Objective:To characterize the relationship between risk factors and otitis media in a rural Alaska Native population ages 1 to 4 yr.Design:This prospective cohort study was a substudy to an analysis of hearing loss determinants in Alaska Native children. This study enrolled Alaska Native children ages 1 to 4 yr from 16 communities in the Bering Strait region of northwest Alaska between October 2021 and August 2022. The aim was to characterize the relationship between environmental, genetic, and dietary risk factors and otitis media in this population, including exposure to household running water, smoke from a wood-burning stove, cigarette smoke, number of people in the household, breastfeeding, and homozygosity for the carnitine palmitoyltransferase 1 (CPT1A) arctic variant, a genetic factor in arctic populations associated with increased risk for respiratory infections. At enrollment and 6-mo follow-up, a parental questionnaire was used to assess environmental risk factors, and ear and hearing status was evaluated through audiometric screening, including tympanometry and otoscopy. A comprehensive chart review was performed to extract data from health care visits containing ICD-10 codes for otitis media. Descriptive statistics were used to summarize demographic data, and logistic regression models were used to identify associations between risk factors and otitis media incidence.Results:There were 245 children enrolled in the study, and the final analytic sample consisted of 236 Alaska Native children ages 1 to 4 yr. The median age was 3.0 yr, and females made up 50% of the sample. Regarding heritage, 63% were Iñupiaq, 29% were Yupik, and 22% were St. Lawrence Island/Siberian Yupik. Geographically, 73% were from villages in the Norton Sound catchment area, and the remaining 27% were from the regional center of Nome. Of the children in the study, 53% were homozygous for the CPT1A arctic variant gene. Among the key risk factors identified, 72% of children had a history of being breastfed, 23% lacked household running water, and 6% were exposed to wood smoke. The mean number of people in the household was 6.2, and the mean number of people who currently smoked tobacco in the household was 1.1. The mean ratio of people who smoked tobacco to adults in the household was 0.4. During the 6-mo study period, 53% of children were diagnosed with one or more episodes of otitis media. CPT1A arctic variant homozygosity showed a trend toward a positive association with 6-mo cumulative odds of otitis media and moderating the effect of other risk factors on the odds of otitis media incidence.Conclusion:Otitis media is common in this population of rural Alaska Native children. CPT1A arctic variant homozygosity increased both the odds of otitis media incidence and the effect of all studied risk factors on otitis media incidence. Results should be interpreted cautiously, as the coronavirus disease 2019 pandemic negatively affected enrollment and likely affected the incidence of otitis media. Further prospective research is needed to better understand these relationships.

This study reports the effects of stimulation level and stimulation rate on the phase locking value (PLV)-an index quantifying neural synchrony of the cochlear nerve (CN)-in postlingually deafened adult cochlear implant users. PLVs were measured at three to four electrode locations at five stimulation levels or at six stimulation rates in 17 participants. Linear mixed-effects models were used to assess the effects of these two parameters on the PLV. Smaller PLVs were measured at the base compared with more apical electrodes across stimulation levels and stimulation rates. The PLV increased with stimulation level but was not affected by stimulation rate up to 120 Hz. In human cochlear implant users, neural synchrony of the CN increases with stimulation level and is not affected by stimulation rate up to 120 Hz. In electrical hearing, these parametric effects are not altered by the pathological changes in the CN.