Objective and subjective efficacy of hearing aids in patients with mild-to-moderate unilateral hearing loss: a prospective study.

PURPOSE: In patients with unilateral sensorineural hearing loss (USNHL), we explored both objective functional audiological gains and subjective satisfaction, indicating when a unilateral hearing aid is valuable. METHODS: Thirty-seven patients with mild-to-moderate USNHL (mean pure-tone thresholds between 25 and 70 dB) were prescribed unilateral hearing aids. Functional gain, the aided speech discrimination score (SDS), the Hearing in Noise Test (HINT) score, and the sound localization test score were collected, and a questionnaire (the Hearing Handicap Inventory for the Elderly, HHIE) completed after 1, 2, and 3 months of hearing aid use. We classified the participants as having 'no handicap' (HHIE < 17), 'mild-to-moderate handicap' (17-42), and 'significant handicap' (> 42). RESULTS: The decrease in handicap afforded by unilateral hearing aids was largest in the 'significant handicap' group (the HHIE total score fell from 59.1 to 37.2; P = 0.007). There were no between-group differences in either functional gain or the aided SDS. Only the 'significant handicap' group evidenced an improved HINT score; the composite signal-to-noise ratio (SNR) fell from - 1.5 to - 2.2 dB [S/N] (P = 0.023). The HHIE usefully indicated when a hearing aid alleviated the discomfort of USNHL; patients with unaided HHIE scores ≥ 20 evidenced significant decreases in the composite SNR (- 1.7 to - 2.0 dB [S/N]; P = 0.045). CONCLUSIONS: When considering whether to prescribe a unilateral hearing aid for patients with mild-to-moderate USNHL, it is helpful to use the HHIE to evaluate discomfort. If the total score is ≥ 20, a hearing aid is appropriate.

The German hearing in noise test with a female talker: development and comparison with German male speech test.

PURPOSE: The aim of the study was to develop the German Hearing in Noise Test (HINT) with female speaker by fulfilling the recommendations by International Collegium of Rehabilitative Audiology (ICRA) for using a female speaker to create new multilingual speech tests and to determine norms and to compare these norms with German male speech tests-the male speakers HINT and the Oldenburg Sentence Test (OLSA). METHODS: The HINT with a female speaker consists of the same speech material as the male speaking HINT. After recording the speech material, 10 normal hearing subjects were included to determine the performance-intensity function (PI function). 24 subjects were part of the measurements to determine the norms and compare them with the norms of male HINT and OLSA. Comparably, adaptive, open-set methods under headphones (HINT) and sound field (OLSA) were used. RESULTS: Acoustic phonetic analysis demonstrated significant difference in mean fundamental frequency, its range and mean speaking rate between both HINT speakers. The calculated norms by three of the tested four conditions of the HINT with a female speaker are not significantly different from the norms with a male speaker. No significant effect of the speaker's gender of the first HINT measurement and no significant correlation between the threshold results of the HINT and the OLSA were determined. CONCLUSIONS: The Norms for German HINT with a female speaker are comparable to the norms of the HINT with a male speaker. The speech intelligibility score of the HINT does not depend on the speakers' gender despite significant difference of acoustic-phonetic parameters between the female and male HINT speaker's voice. Instead, the speech intelligibility rating must be seen as a function of the used speech material.

Can visual capture of sound separate auditory streams?

In noisy contexts, sound discrimination improves when the auditory sources are separated in space. This phenomenon, named Spatial Release from Masking (SRM), arises from the interaction between the auditory information reaching the ear and spatial attention resources. To examine the relative contribution of these two factors, we exploited an audio-visual illusion in a hearing-in-noise task to create conditions in which the initial stimulation to the ears is held constant, while the perceived separation between speech and masker is changed illusorily (visual capture of sound). In two experiments, we asked participants to identify a string of five digits pronounced by a female voice, embedded in either energetic (Experiment 1) or informational (Experiment 2) noise, before reporting the perceived location of the heard digits. Critically, the distance between target digits and masking noise was manipulated both physically (from 22.5 to 75.0 degrees) and illusorily, by pairing target sounds with visual stimuli either at same (audio-visual congruent) or different positions (15 degrees offset, leftward or rightward: audio-visual incongruent). The proportion of correctly reported digits increased with the physical separation between the target and masker, as expected from SRM. However, despite effective visual capture of sounds, performance was not modulated by illusory changes of target sound position. Our results are compatible with a limited role of central factors in the SRM phenomenon, at least in our experimental setting. Moreover, they add to the controversial literature on the limited effects of audio-visual capture in auditory stream separation.

Development and evaluation of the Cantonese matrix sentence test.

OBJECTIVE: To develop the Cantonese matrix (YUEmatrix) test according to the international standard procedure and examine possible different outcomes in another tonal language. DESIGN: A 50-word Cantonese base-matrix was established. Word-specific speech recognition functions, speech recognition thresholds (SRT), and slopes were obtained. The speech material was homogenised in intelligibility by applying level corrections up to ± 3 dB. Subsequently, the YUEmatrix test was evaluated in five aspects: training effect, test-list equivalence, test-retest reliability, establishment of reference data for normal-hearing Cantonese-speakers, and comparison with the Cantonese-Hearing-In-Noise-Test. STUDY SAMPLE: Overall, 64 normal-hearing native Cantonese-speaking listeners. RESULTS: SRT measurements with adaptive procedures resulted in a reference SRT of -9.7 ± 0.7 dB SNR for open-set and -11.1 ± 1.2 dB SNR for the closed-set response format. Fixed SNR measurements suggested a test-specific speech intelligibility function slope of 15.5 ± 0.7%/dB. Seventeen 10-sentences base test lists were confirmed to be equivalent with respect to speech intelligibility. Training effect was not observed after two measurements of 20-sentences lists. CONCLUSIONS: The YUEmatrix yields comparable results to matrix tests in other languages including Mandarin. Level adjustments to homogenise sentences appear to be less effective for tonal languages than for most other languages developed so far.

Envelope following responses predict speech-in-noise performance in normal-hearing listeners.

Permanent threshold elevation after noise exposure or aging is caused by loss of sensory cells; however, animal studies show that hair cell loss is often preceded by degeneration of the synapses between sensory cells and auditory nerve fibers. Silencing these neurons is likely to degrade auditory processing and may contribute to difficulties understanding speech in noisy backgrounds. Reduction of suprathreshold ABR amplitudes can be used to quantify synaptopathy in inbred mice. However, ABR amplitudes are highly variable in humans, and thus more challenging to use. Since noise-induced neuropathy preferentially targets fibers with high thresholds and low spontaneous rate and because phase locking to temporal envelopes is particularly strong in these fibers, measuring envelope following responses (EFRs) might be a more robust measure of cochlear synaptopathy. A recent auditory model further suggests that modulation of carrier tones with rectangular envelopes should be less sensitive to cochlear amplifier dysfunction and, therefore, a better metric of cochlear neural damage than sinusoidal amplitude modulation. In this study, we measure performance scores on a variety of difficult word-recognition tasks among listeners with normal audiograms and assess correlations with EFR magnitudes to rectangular versus sinusoidal modulation. Higher harmonics of EFR magnitudes evoked by a rectangular-envelope stimulus were significantly correlated with word scores, whereas those evoked by sinusoidally modulated tones did not. These results support previous reports that individual differences in synaptopathy may be a source of speech recognition variability despite the presence of normal thresholds at standard audiometric frequencies.NEW & NOTEWORTHY Recent studies suggest that millions of people may be at risk of permanent impairment from cochlear synaptopathy, the age-related and noise-induced degeneration of neural connections in the inner ear. This study examines electrophysiological responses to stimuli designed to improve detection of neural damage in subjects with normal hearing sensitivity. The resultant correlations with word recognition performance are consistent with a contribution of cochlear neural damage to deficits in hearing in noise abilities.

Acute Alcohol Intake Deteriorates Hearing Thresholds and Speech Perception in Noise.

OBJECTIVES: The hearing process involves complex peripheral and central auditory pathways and could be influenced by various situations or medications. To date, there is very little known about the effects of alcohol on the auditory performances. The purpose of the present study was to evaluate how acute alcohol administration affects various aspects of hearing performance in human subjects, from the auditory perceptive threshold to the speech-in-noise task, which is cognitively demanding. METHODS: A total of 43 healthy volunteers were recruited, and each of the participants received calculated amounts of alcohol according to their body weight and sex with a targeted blood alcohol content level of 0.05% using the Widmark formula. Hearing was tested in alcohol-free conditions (no alcohol intake within the previous 24 h) and acute alcohol conditions. A test battery composed of pure-tone audiometry, speech reception threshold (SRT), word recognition score (WRS), distortion product otoacoustic emission (DPOAE), gaps-in-noise (GIN) test, and Korean matrix sentence test (testing speech perception in noise) was performed in the 2 conditions. RESULTS: Acute alcohol intake elevated pure-tone hearing thresholds and SRT but did not affect WRS. Both otoacoustic emissions recorded with DPOAE and the temporal resolution measured with the GIN test were not influenced by alcohol intake. The hearing performance in a noisy environment in both easy (-2 dB signal-to-noise ratio [SNR]) and difficult (-8 dB SNR) conditions was decreased by alcohol. CONCLUSIONS: Acute alcohol elevated auditory perceptive thresholds and affected performance in complex and difficult auditory tasks rather than simple tasks.

Benefits in noise from sound processor upgrade in thirty-three cochlear implant users for more than 20 years.

PURPOSE: Some oldest patients rehabilitated with a cochlear implant more than 20 years ago could still be upgraded with new generations of speech processor (SP). The aim of this study was to show the benefit of a recent generation of SP in this population. METHODS: A monocentric prospective study was designed to evaluate the performance of 33 ancient CI22M users implanted between 1989 and 1997 and upgraded with the late compatible sound processor CP900. Performance was evaluated in quiet and noise with Framatix, an automated adaptative test. RESULTS: Performance using Framatix significantly improved with the CP900, with a decrease of the median speech perception threshold of 6 dB in quiet (p < 0.05) and 5,3 dB in noise (p < 0.0005). No subjective benefit using the APHAB questionnaire was observed. CONCLUSION: Upgrading of cochlear implant recipients who were implanted more than 20 years ago with recent compatible and new technological SP provide benefit in speech recognition in noise.

Effect of eye closure on speech recognition in noise: in light and in darkness.

OBJECTIVE: This study evaluated whether listening with an eye closure (EC) strategy improves speech recognition in noise (SRN) under different visual conditions. Previous research suggests EC may enhance activation of cortical systems involved in listening and attention. Study hypotheses were that EC listening leads to better SRN than eyes open listening, that listening in darkness leads to better SRN than in light, and EC listening leads to more improved SRN in light compared to darkness. DESIGN: SRN with the Cantonese Hearing in Noise Test (CHINT) under four conditions was assessed: (1) eyes open with lights on, (2) EC with lights on, (3) eyes open in darkened room, and (4) EC in darkened room. ANOVA determined potential differences among conditions and effect sizes were calculated. STUDY SAMPLE: Fifty-six young adults (age range 18-35 years) with bilaterally normal hearing. RESULTS: Significant effects for EC and presence/absence of an external visual stimulus on SRN were found. Post-hoc analysis found a statistically significant difference between eyes open and closed in light, with a large effect size, indicating EC resulted in the greatest improvement in SRN when in the presence of an external visual stimulus. However, differences compared with known CHINT inter-list variability lacked clinical importance. CONCLUSIONS: EC did significantly improve SRN and is a potential strategy for challenging listening situations when feasible, although no changes are needed for CHINT norms or testing procedures in relation to EC status.

Electrophysiological markers of cochlear function correlate with hearing-in-noise performance among audiometrically normal subjects.

Hearing loss caused by noise exposure, ototoxic drugs, or aging results from the loss of sensory cells, as reflected in audiometric threshold elevation. Animal studies show that loss of hair cells can be preceded by loss of auditory-nerve peripheral synapses, which likely degrades auditory processing. While this condition, known as cochlear synaptopathy, can be diagnosed in mice by a reduction of suprathreshold cochlear neural responses, its diagnosis in humans remains challenging. To look for evidence of cochlear nerve damage in normal hearing subjects, we measured their word recognition performance in difficult listening environments and compared it to cochlear function as assessed by otoacoustic emissions and click-evoked electrocochleography. Several electrocochleographic markers were correlated with word scores, whereas distortion product otoacoustic emissions were not. Specifically, the summating potential (SP) was larger and the cochlear nerve action potential (AP) was smaller in those with the worst word scores. Adding a forward masker or increasing stimulus rate reduced SP in the worst performers, suggesting that this potential includes postsynaptic components as well as hair cell receptor potentials. Results suggests that some of the variance in word scores among listeners with normal audiometric threshold arises from cochlear neural damage.NEW & NOTEWORTHY Recent animal studies suggest that millions of people may be at risk of permanent impairment from cochlear synaptopathy, the age-related and noise-induced degeneration of neural connections in the inner ear that "hides" behind a normal audiogram. This study examines electrophysiological responses to clicks in a large cohort of subjects with normal hearing sensitivity. The resultant correlations with word recognition performance are consistent with an important contribution cochlear neural damage to deficits in hearing in noise abilities.

Development of the Farsi Hearing in Noise Test.

Objectives: Develop sentences in Farsi for use in the Hearing In Noise Test (HINT); equalise the difficulty of the sentences; form twelve 20-sentence lists; and determine the reliability and norms for these materials.Design: The same study design as used in the development of HINT in other languages was followed. Sentences were sampled from elementary school reading materials. Sentence difficulty was matched by scaling sentence levels. Equivalent sentence lists were formed. Speech reception thresholds were measured under headphones in quiet and in three noise conditions that differed in the spatial locations of the speech and noise sources. Spatial locations were simulated using head-related transfer functions.Study sample: Subjects were 24 adult native speakers of Farsi with pure-tone thresholds ≤25 dB HL at audiometric frequencies from 0.25 to 8.00 kHz.Results: Reliability, the variability of test-retest score differences, was 1.28 dB in quiet and 1.08 dB in noise. Average speech reception thresholds in Quiet = 19.4 dB(A). Average signal/noise ratios at threshold were Noise Front = -5.4 dB, Noise Right = -13.7 dB, and Noise Left = -13.7.Conclusions: The reliability and norms for the Farsi HINT are comparable to those for other languages, enabling comparison of test results across languages.

The cocktail party effect in the domestic dog (Canis familiaris).

Like humans, canine companions often find themselves in noisy environments, and are expected to respond to human speech despite potential distractors. Such environments pose particular problems for young children, who have limited linguistic knowledge. Here, we examined whether dogs show similar difficulties. We found that dogs prefer their name to a stress-matched foil in quiet conditions, despite hearing it spoken by a novel talker. They continued to prefer their name in the presence of multitalker human speech babble at signal-to-noise levels as low as 0 dB, when their name was the same intensity as the foil. This surpasses the performance of 1-year-old infants, who fail to prefer their name to a foil at 0 dB (Newman in Dev Psychol 41(2):352-362, 2005). Overall, we find better performance at name recognition in dogs that were trained to do tasks for humans, like service dogs, search-and-rescue dogs, and explosives detection dogs. These dogs were of several different breeds, and their tasks were widely different from one another. This suggests that their superior performance may be due to generally more training and better attention. In summary, these results demonstrate that dogs can recognize their name even in relatively difficult levels of multitalker babble, and that dogs who work with humans are especially adept at name recognition in comparison with companion dogs. Future studies will explore the effect of different types of background noise on word recognition in dogs.

Long-term evaluation of sound localisation in single-sided deaf adults fitted with a BAHA device.

OBJECTIVE: To perform a long-term evaluation of the localisation capabilities in the horizontal plane of single-sided deaf patients fitted with a BAHA device. DESIGN: Single-centre retrospective study. PARTICIPANTS: Twenty-one adults with single-sided deafness (SSD) with normal hearing in the contralateral ear (pure tone average <20 dB, SDS > 90%) rehabilitated with a Cochlear BAHA device from 2003 to 2012 on the deaf side over a median follow-up of 8 years. OUTCOME MEASURES: The task used in this paper is a sound localisation identification task with a set-up of seven loudspeakers on a semi-circular array at 30-degree intervals performed at three periods: before BAHA, initially and at last follow-up. Our main criterion of judgement was the root-mean-square (RMS) localisation error. In addition, the Bern Benefit in Single-Sided Deafness Questionnaire (BBSS) was administered. RESULTS: The mean RMS localisation error was initially estimated at 64° without any rehabilitation (for a chance level RMS estimated at 81°). Initially, with the BAHA device, the RMS localisation error dropped to 51°. At the last follow-up evaluation, a significant decrease at 23° was noted. Concerning the Bern Questionnaire, 19% of the patients (n = 4) did not report any change (score of 0), 33% (n = 7) are satisfied (score of +1 or +2) and 48% (n = 10) are very satisfied with the BAHA device (score better than +3). CONCLUSION: Improvement of sound localisation in the horizontal plane for some SSD patients is likely related to altered processing of monaural spectral cues. The time needed to learn to use the azimuth-dependent spectral cues takes time. Long-term follow-up should be considered for studies investigating sound localisation performance.

Extended bandwidth nonlinear frequency compression in Mandarin-speaking hearing-aid users.

BACKGROUND/PURPOSE: The high frequency information of consonant messages is important for recognition of speech. Recently, the nonlinear frequency compression (NLFC) technique has been shown to improve the speech perception in patients with high frequency hearing loss. In Mandarin, seven consonants are located over 10-16 kHz. Extended-bandwidth (EB) NLFC may provide an additional benefit for recognition of Mandarin words. The purpose of this study was to explore the effects of NLFC and EB-NLFC on Mandarin word recognition in patients with high frequency hearing loss. METHODS: Fourteen native Mandarin-speaking adult patients, aged 20-65 years with bilateral, moderate to severe, sensorineural hearing loss, specifically high frequency hearing loss were included in single-blind randomized study. The assessment tools included the Mandarin Monosyllable Recognition Test (MMRT), Mandarin Hearing in Noise Test (MHINT), and International Outcome Inventory for Hearing Aids (IOI-HA) and sound quality scale of the hearing aids. The patients were tested under unaided condition, after which they were randomly assigned to wear NLFC and EB-NLFC hearing aids, alternatively, in a crossover fashion. After each 4-week block, the patients were tested again to obtain the test outcomes. RESULTS: Patients with hearing aids with EB-NLFC had a significantly better word and consonant recognition using the MMRT (p<0.05). The MHINT was better for the EB-NLFC group without significant differences. The EB-NLFC group had better scores in both the IOI-HA and sound quality scale but not statistically significant. CONCLUSION: Patients with high-frequency hearing loss may benefit more from using EB-NLFC for word and consonant recognition; however, the improvement was small under a noisy listening environment. The subjective questionnaires did not show significant benefit of EB-NLFC either.

Contribution of spiking activity in the primary auditory cortex to detection in noise.

A fundamental problem in hearing is detecting a "target" stimulus (e.g., a friend's voice) that is presented with a noisy background (e.g., the din of a crowded restaurant). Despite its importance to hearing, a relationship between spiking activity and behavioral performance during such a "detection-in-noise" task has yet to be fully elucidated. In this study, we recorded spiking activity in primary auditory cortex (A1) while rhesus monkeys detected a target stimulus that was presented with a noise background. Although some neurons were modulated, the response of the typical A1 neuron was not modulated by the stimulus- and task-related parameters of our task. In contrast, we found more robust representations of these parameters in population-level activity: small populations of neurons matched the monkeys' behavioral sensitivity. Overall, these findings are consistent with the hypothesis that the sensory evidence, which is needed to solve such detection-in-noise tasks, is represented in population-level A1 activity and may be available to be read out by downstream neurons that are involved in mediating this task.NEW & NOTEWORTHY This study examines the contribution of A1 to detecting a sound that is presented with a noisy background. We found that population-level A1 activity, but not single neurons, could provide the evidence needed to make this perceptual decision.

Baha implant as a hearing solution for single-sided deafness after retrosigmoid approach for the vestibular schwannoma: audiological results.

Skull base tumors and, in particular, vestibular schwannoma (VS) are among the etiological reasons for single-sided deafness (SSD). Patients with SSD have problems in understanding speech in a noisy environment and cannot localize the direction of sounds. For the majority, this is the handicap for which they try to find a solution. Apart from CROS hearing aids, Baha is one of the most frequently used systems for SSD compensation. 38 patients with single-sided deafness after retrosigmoid removal of a vestibular schwannoma underwent testing with a Baha softband from September 2010 to August 2014. Sixteen patients (42 %) finally decided to accept Baha implantation. Subjective experience with the Baha softband was evaluated by patients using the BBSS questionnaire immediately after testing. Objective evaluation of the effect was performed as a measurement of the sentence discrimination score in noise and side horizontal discrimination without a Baha and 6 weeks and 12 months after a sound processor fitting. There was a significant improvement in sentence discrimination in the 6 week (64.0 %) and 1 year (74.6 %) interval of follow-up in comparison with understanding without Baha (24.0 %, p = 0.001) in situations when sentences are coming from the side of the non-hearing ear and noise contralaterally with SNR -5 dB. Baha can significantly improve sentence discrimination in complex-listening situation in patients with SSD after the VS surgery.

The effect of non-native and non-regional speech testing on a multi-lingual population.

OBJECTIVE: This study was conducted to evaluate the speech perception of Malaysian Chinese adults using the Taiwanese Mandarin HINT (MHINT-T) and the Malay HINT (MyHINT). DESIGN: The MHINT-T and the MyHINT were presented in quiet and noise (front, right and left) conditions under headphones. Results for the two tests were compared with each other and with the norms for each test. STUDY SAMPLE: Malaysian Chinese native speakers of Mandarin (N = 58), 18-31 years of age with normal hearing. RESULTS: On average, subjects demonstrated poorer speech perception ability than the normative samples for these tests. Repeated measures ANOVA showed that speech reception thresholds (SRTs) were slightly poorer on the MHINT-T than on the MyHINT for all test conditions. However, normalized SRTs were poorer by 0.6 standard deviations for MyHINT as compared with MHINT-T. CONCLUSIONS: MyHINT and MHINT-T can be used as norm-referenced speech perception measures for Mandarin-speaking Chinese in Malaysia.

Speech Masking in Normal and Impaired Hearing: Interactions Between Frequency Selectivity and Inherent Temporal Fluctuations in Noise.

Recent studies in normal-hearing listeners have used envelope-vocoded stimuli to show that the masking of speech by noise is dominated by the temporal-envelope fluctuations inherent in noise, rather than just overall power. Because these studies were based on vocoding, it was expected that cochlear-implant (CI) users would demonstrate a similar sensitivity to inherent fluctuations. In contrast, it was found that CI users showed no difference in speech intelligibility between maskers with and without inherent envelope fluctuations. Here, these initial findings in CI users were extended to listeners with cochlear hearing loss and the results were compared with those from normal-hearing listeners at either equal sensation level or equal sound pressure level. The results from hearing-impaired listeners (and in normal-hearing listeners at high sound levels) are consistent with a relative reduction in low-frequency inherent noise fluctuations due to broader cochlear filtering. The reduced effect of inherent temporal fluctuations in noise, due to either current spread (in CI users) or broader cochlear filters (in hearing-impaired listeners), provides a new way to explain the loss of masking release experienced in CI users and hearing-impaired listeners when additional amplitude fluctuations are introduced in noise maskers.

Quantification of the effects of Mandarin dialect differences on the use of norm-referenced speech perception tests.

OBJECTIVE: Determine the effects of Chinese dialects on results for the Mandarin HINT recorded with a talker speaking Standard Mandarin (Putonghua). DESIGN: Normally-hearing subjects with different dialect exposure histories and usage preferences were administered the Mandarin HINT, and results were compared with published norms. Additional published measures of the intelligibility and mutual intelligibility of Chinese dialects were used to identify dialects for which Putonghua is highly intelligible. STUDY SAMPLE: One sample (N = 19) was exposed to a variety of dialects throughout China during childhood, and used Putonghua as adults. A second sample (N = 22) was exposed to Sichuanhua (the dialect found in Sichuan province) during childhood, and used Sichuanhua as adults. RESULTS: The average difference in SRTs for the Putonghua and Sichuanhua groups was 0.66 dB, with the Sichuanhua group's SRTs slightly higher. Means for neither group fell outside the confidence intervals for the norms. Putonghua is intelligible for 98% of Sichuanhua dialect users, and for over 90% of the users of two-thirds of the remaining Chinese regional dialects. CONCLUSIONS: Norm-referenced speech perception tests, such as the Mandarin HINT, can be used with speakers of Chinese regional dialects for whom Putonghua is highly intelligible. Small differences in dialect-specific norms are not clinically significant.

Exploring the Differences Between an Immature and a Mature Human Auditory System Through Auditory Late Responses in Quiet and in Noise.

Children are disadvantaged compared to adults when they perceive speech in a noisy environment. Noise reduces their ability to extract and understand auditory information. Auditory-Evoked Late Responses (ALRs) offer insight into how the auditory system can process information in noise. This study investigated how noise, signal-to-noise ratio (SNR), and stimulus type affect ALRs in children and adults. Fifteen participants from each group with normal hearing were studied under various conditions. The findings revealed that both groups experienced delayed latencies and reduced amplitudes in noise but that children had fewer identifiable waves than adults. Babble noise had a significant impact on both groups, limiting the analysis to one condition: the /da/ stimulus at +10 dB SNR for the P1 wave. P1 amplitude was greater in quiet for children compared to adults, with no stimulus effect. Children generally exhibited longer latencies. N1 latency was longer in noise, with larger amplitudes in white noise compared to quiet for both groups. P2 latency was shorter with the verbal stimulus in quiet, with larger amplitudes in children than adults. N2 latency was shorter in quiet, with no amplitude differences between the groups. Overall, noise prolonged latencies and reduced amplitudes. Different noise types had varying impacts, with the eight-talker babble noise causing more disruption. Children's auditory system responded similarly to adults but may be more susceptible to noise. This research emphasizes the need to understand noise's impact on children's auditory development, given their exposure to noisy environments, requiring further exploration of noise parameters in children.

Enhancing Cochlear Implant Outcomes across Age Groups: The Interplay of Forward Focus and Advanced Combination Encoder Coding Strategies in Noisy Conditions.

Background: Hearing in noise is challenging for cochlear implant users and requires significant listening effort. This study investigated the influence of ForwardFocus and number of maxima of the Advanced Combination Encoder (ACE) strategy, as well as age, on speech recognition threshold and listening effort in noise. Methods: A total of 33 cochlear implant recipients were included (age ≤ 40 years: n = 15, >40 years: n = 18). The Oldenburg Sentence Test was used to measure 50% speech recognition thresholds (SRT50) in fluctuating and stationary noise. Speech was presented frontally, while three frontal or rear noise sources were used, and the number of ACE maxima varied between 8 and 12. Results: ForwardFocus significantly improved the SRT50 when noise was presented from the back, independent of subject age. The use of 12 maxima further improved the SRT50 when ForwardFocus was activated and when noise and speech were presented frontally. Listening effort was significantly worse in the older age group compared to the younger age group and was reduced by ForwardFocus but not by increasing the number of ACE maxima. Conclusion: Forward Focus can improve speech recognition in noisy environments and reduce listening effort, especially in older cochlear implant users.