Objectives:The goal of this study was to determine if performance on speech and non-speech clinical measures of auditory perception differs between two groups of adults: self-identified native speakers of English and non-native speakers of English who speak Spanish as a first language. The overall objective was to establish whether auditory perception tests developed for native English speakers are appropriate for bilingual Spanish-speaking adults who self-identify as non-native speakers of English. A secondary objective was to determine whether relative performance on English- and Spanish-language versions of a closed-set speech perception in noise task could accurately predict native-like performance on a battery of English language-dependent tests of auditory perception.Design:Participants were young, normal-hearing adults who self-identified as either native speakers of American English (n = 50) or as non-native speakers of American English (NNE; n = 25) who spoke Spanish as their first language. Participants completed a battery of perceptual tests, including speech tests (e.g., Quick Speech-in-Noise, time-compressed reverberant Quick Speech-in-Noise, etc.) and non-speech tests (Gaps in Noise, Frequency Pattern test, Duration Pattern test, Masking Level Difference). The English version of the Oldenburg Sentence test (OLSA) was administered to both groups; NNE participants also completed the Spanish version of the OLSA.Results:Analyses indicate that the native speakers of the American English group performed significantly better than the NNE group on all speech-based tests and on the two pattern recognition tests. There was no difference between groups on the remaining non-speech tests. For the NNE group, a difference of more than 2 SD on group-normalized scores for the English and Spanish OLSA accurately predicted poorer than normal performance on two or more tests of auditory perception with a language-dependent component either in the instructions or the stimuli.Conclusions:The results indicate that a number of English-based tests designed to assess auditory perception may be inappropriate for some Spanish-English bilingual adults. That is, some bilingual adults may perform worse than expected on tests that involve perceiving spoken English, in part because of linguistic differences, and not because of unusually poor auditory perception. The results also support the use of preliminary speech-in-noise screening tests in each of a bilingual patient's languages to establish if auditory perception tests in English are appropriate for a given individual. If a non-native English speaker's screening performance is worse in English than in the native language, one suggested strategy is to select auditory perceptual tests that are impacted minimally or not at all by linguistic differences.

Purpose: Some bilinguals may exhibit lower performance when understanding speech in noise (SIN) in their second language (L2) compared to monolinguals in their first language. Poorer performance has been found mostly for late bilinguals (L2 acquired after childhood) listening to sentences containing linguistic context, and less so for simultaneous/early bilinguals (L2 acquired during childhood) and when testing context-free stimuli. However, most previous studies tested younger participants, meaning little is known about interactions with age; the purpose of this study was to address this gap.Method: Context-free SIN understanding was measured via the Modified Rhyme Test (MRT) in 3836 young and middle-aged bilingual and monolingual adults (ages 18–57; 19.5% bilinguals, all L2 English) with normal to near-normal hearing. Bilingual adults included simultaneous (n = 466), early (n = 185), and late (n = 97) bilinguals. Performance on the MRT was measured with both accuracy and response time. A self-reported measure of current English use was also collected for bilinguals to evaluate its impact on MRT performance.Results: Age impacted MRT accuracy scores differently for each listener group. Relative to monolinguals, simultaneous and early bilinguals showed decreased performance with older age. Response times slowed with older age at similar rates for all groups, despite faster overall response times for monolinguals. Among all bilingual listeners, greater current English language use predicted higher MRT accuracy. For simultaneous bilinguals, greater English use was associated with faster response times. Conclusions: Speech-in-noise outcomes in bilingual adults are impacted not only by fixed features of their language history (i.e. age of acquisition) but also by language practices which can shift over time (i.e. current language use), supporting routine querying of language history and use in the Audiology clinic.

Transcutaneous auricular vagus nerve stimulation (taVNS) is a neuromodulatory technique that may have numerous potential health and human performance benefits. However, optimal stimulation parameters for maximizing taVNS efficacy are unknown. Progress is impeded by disagreement on the identification of a biomarker that reliably indexes activation of neuromodulatory systems targeted by taVNS, including the locus coeruleus-norepinephrine (LC-NE) system. Pupil size varies with LC-NE activity and is one potential taVNS biomarker that has shown inconsistent sensitivity to taVNS in prior studies. The present study examined the relationship between pupil size and taVNS using stimulation parameters that have shown promising behavioral effects in prior studies but have received comparatively little attention. Participants received trains of 50 μs taVNS pulses delivered continuously below perceptual threshold at 300 Hz to the left external acoustic meatus (EAM) while pupil size was recorded during a pupillary light reflex task. Analysis of pupil size using generalized additive mixed modeling (GAMM) revealed a non-linear relationship between taVNS intensity and pupil diameter. Active taVNS increased pupil size during stimulation for participants who received taVNS between 2 and approximately 4.8 mA, but not for participants who received higher-intensity taVNS (up to 8.1 mA). In addition, taVNS effects persisted in subsequent blocks, mitigating decreases in pupil size over the course of the task. These findings suggest 300 Hz taVNS activates the LC-NE system when applied to the EAM, but its effects may be counteracted at higher intensities.

Virtual reality (VR) is usually used to simulate complex visual scenes with a head-mounted display (HMD). However, VR can also be used to obtain better control over the visual environment and to monitor ocular dynamics during listening experiments. In this study, a low-cost HMD was used to track eye gaze and pupil diameter during a dichotic listening task in a simple virtual environment that simulated a computer display. The pupillometry results from the VR environment were compared to those obtained on the same task with a desktop monitor research-grade eye tracker. Participants recalled digits in the right ear and ignored interfering digits in the left ear. It was hypothesized that greater pupil dilation would be observed for dichotic compared to monotic listening with both HMD and research-grade eye trackers. Preliminary data support this hypothesis. The HMD was also evaluated for its potential to collect eye-tracking data in tablet-based clinical speech-in-noise tasks not originally designed for pupillometry. Results suggest that the task-evoked pupil response can be measured with the HMD on clinical tasks and a VR-based system has potential as a low-cost clinical tool to collect objective measures of listening effort.

Transcutaneous auricular vagus nerve stimulation (taVNS) is a neuromodulatory technique that may have numerous potential health and human performance benefits. However, optimal stimulation parameters for maximizing taVNS efficacy are unknown. Progress is impeded by disagreement on the identification of a biomarker that reliably indexes activation of neuromodulatory systems targeted by taVNS, including the locus coeruleus-norepinephrine (LC-NE) system. Pupil size varies with LC-NE activity and is one potential taVNS biomarker that has shown inconsistent sensitivity to taVNS in prior studies. The present study examined the relationship between pupil size and taVNS using stimulation parameters that have shown promising behavioral effects in prior studies but have received comparatively little attention. Participants received 30-second trains of 50 μs taVNS pulses delivered below perceptual threshold at 300 Hz to the left external acoustic meatus (EAM) while pupil size was recorded during a pupillary light reflex task. Analysis of pupil size using generalized additive mixed modelling (GAMM) revealed a nonlinear relationship between taVNS intensity and pupil diameter. Active taVNS increased pupil size during stimulation for participants who received taVNS between 2 and approximately 4.8 mA, but not for participants who received higher intensity taVNS (up to 8.1 mA). In addition, taVNS effects persisted in subsequent blocks, mitigating decreases in pupil size over the course of the task. These findings suggest 300 Hz taVNS activates the LC-NE system when applied to the EAM, but its effects may be counteracted at higher intensities.### Competing Interest StatementThe authors have declared no competing interest.

Purpose: The purpose of this study was to explore potential differences in suprathreshold auditory function among native and nonnative speakers of English as a function of age. Method: Retrospective analyses were performed on three large datasets containing suprathreshold auditory tasks completed by 5572 participants who were self-identified native and nonnative speakers of English between the ages of 18–65, including a binaural tone detection task, a digit identification task, and a sentence recognition task.Results: The analyses show a significant interaction between increasing age and participant group on tasks involving speech-based stimuli (digit strings, sentences) but not on the binaural tone detection task. For both speech tasks, differences in speech recognition emerged between groups during early adulthood and increasing age had a more negative impact on word recognition for nonnative compared to native participants. Age-related declines in performance were 2.9 times faster for digit strings and 3.3 times faster for sentences for nonnative participants compared to native participants. Conclusions: This set of analyses extends the existing literature by examining interactions between aging and language background in several auditory domains in a cohort of adults spanning young adulthood through middle age. The finding that older nonnative English speakers in this age cohort may have greater than expected deficits on speech-in-noise perception may have clinical implications on how these individuals should be diagnosed and treated for hearing difficulties.

Some bilinguals may perform worse understanding speech in noise (SIN) in their second language (L2) compared to monolinguals. Poorer performance has been found mostly for late bilinguals (L2 acquired after childhood) listening to sentences containing linguistic context, and less so for simultaneous/early bilinguals (L2 acquired during childhood) and when testing context-free stimuli. However, most studies tested younger participants–little is known about interactions with age. This study addresses this gap by measuring context-free SIN understanding via the Modified Rhyme Test in over 2,000 normal-hearing young and middle-aged bilingual and monolingual adults (ages 18–58; 23% bilinguals, all L2 English). Data collection is ongoing. Interim analyses reveal an interaction of age and group. Word recognition accuracy decreased as age increased for simultaneous and early bilinguals, but was stable for monolinguals and late bilinguals (though worse for bilinguals than monolinguals). Response time was faster for monolinguals but all groups slowed with increasing age at similar rates. These findings suggest an exaggerated age effect for bilingual SIN understanding across early and middle adulthood. [The views expressed in this abstract are those of the author(s) and do not necessarily reflect the official policy of the Department of Defense or the U.S. Government.]

Pure-tone thresholds are often a poor predictor of hearing difficulties experienced by patients in audiology clinics. Approximately 25 million Americans may experience hearing difficulties despite having audiometric thresholds within normal limits. Pupil diameter increases with increasing listening effort and could provide an objective measure for determining the presence of such subclinical hearing problems. However, the cost and technical requirements of research-grade eye trackers have limited their use in audiology clinics. This study aims to determine the feasibility of using a commercially-available head mounted display (HMD) with integrated eye tracking to collect pupillometry measures during audiological testing. Pupillary data were collected for N = 46 younger normal-hearing adults while they completed clinically-relevant tests including pure tone audiometry, gaps-in-noise (GIN), dichotic digits, and speech-in-noise tests. Across tasks, task-evoked pupillary responses were generally sensitive to differences in listening demands. Results suggest audiologic testing with commercial HMD eye trackers is feasible and provides additional objective information related to listening effort that may help clinicians better understand and address patient needs. [The views expressed in this abstract are those of theauthors and do not reflect the official policy of the Department of Army/Navy/Air Force, Department of Defense, or U.S. Government.]

Speech recognition in noisy environments can be challenging and requires listeners to accurately segregate a target speaker from irrelevant background noise. Stochastic figure-ground (SFG) tasks in which temporally coherent inharmonic pure-tones must be identified from a background have been used to probe the non-linguistic auditory stream segregation processes important for speech-in-noise processing. However, little is known about the relationship between performance on SFG tasks and speech-in-noise tasks nor the individual differences that may modulate such relationships. In this study, 37 younger normal-hearing adults performed an SFG task with target figure chords consisting of four, six, eight, or ten temporally coherent tones amongst a background of randomly varying tones. Stimuli were designed to be spectrally and temporally flat. An increased number of temporally coherent tones resulted in higher accuracy and faster reaction times (RTs). For ten target tones, faster RTs were associated with better scores on the Quick Speech-in-Noise task. Individual differences in working memory capacity and self-reported musicianship further modulated these relationships. Overall, results demonstrate that the SFG task could serve as an assessment of auditory stream segregation accuracy and RT that is sensitive to individual differences in cognitive and auditory abilities, even among younger normal-hearing adults.

Abstract Difficulty perceiving phonological contrasts in a second language (L2) can impede initial L2 lexical learning. Such is the case for English speakers learning tonal languages, like Mandarin Chinese. Given the hypothesized role of reduced neuroplasticity in adulthood limiting L2 phonological perception, the current study examined whether transcutaneous auricular vagus nerve stimulation (taVNS), a relatively new neuromodulatory technique, can facilitate L2 lexical learning for English speakers learning Mandarin Chinese over 2 days. Using a double-blind design, one group of participants received 10 min of continuous priming taVNS before lexical training and testing each day, a second group received 500 msec of peristimulus (peristim) taVNS preceding each to-be-learned item in the same tasks, and a third group received passive sham stimulation. Results of the lexical recognition test administered at the end of each day revealed evidence of learning for all groups, but a higher likelihood of accuracy across days for the peristim group and a greater improvement in response time between days for the priming group. Analyses of N400 ERP components elicited during the same tasks indicate behavioral advantages for both taVNS groups coincided with stronger lexico-semantic encoding for target words. Comparison of these findings to pupillometry results for the same study reported in Pandža, N. B., Phillips, I., Karuzis, V. P., O'Rourke, P., and Kuchinsky, S. E. (Neurostimulation and pupillometry: New directions for learning and research in applied linguistics. Annual Review of Applied Linguistics, 40, 56–77, 2020) suggest that positive effects of priming taVNS (but not peristim taVNS) on lexico-semantic encoding are related to sustained attentional effort.

This paper begins by discussing new trends in the use of neurostimulation techniques in cognitive science and learning research, as well as the nascent research on their application in second language learning. To illustrate this, an experiment designed to investigate the impact of transcutaneous vagus nerve stimulation (tVNS), which is delivered via earbuds, on how learners process and learn Mandarin tones is reported. Pupillometry, which is an index of cognitive effort, is explained and illustrated as one way to assess the impact of tVNS. Participants in the study were native English speakers, naive to tone languages, pseudorandomly assigned to active or control conditions, while balancing for nonlinguistic pitch ability and musical experience. Their performance after tVNS was assessed using a range of more traditional language outcome measures, including accuracy and reaction times from lexical recognition and recall tasks and was triangulated with pupillometry during word-learning to help understand the mechanism through which tVNS operates. Findings are discussed in light of the literatures on lexical tone learning, cognitive effort, and neurostimulation, including specific benefits for learners of tone languages. Recommendations are made for future work on the increasingly popular area of neurostimulation for the field of applied linguistics in the 40th anniversary issue of ARAL.