Understanding Of Noise Research Articles

Evaluation of a personalized auditory-cognitive training on the improvement of speech understanding in noise in cochlear implanted patients

Objective The cochlear implant is a commonly used implantable device for the auditory rehabilitation of severe bilateral sensorineural hearing loss. The effectiveness of the implant, depends on many factors, including intensive auditory training, which is crucial. Intelligibility in a noisy environment is a current issue and poses a major difficulty for implanted patients. The aim of this study is to evaluate the improvement in auditory performance in noise among cochlear implant patients who underwent personalized auditory-cognitive training for speech understanding tasks in noise. Design This was a prospective study involving cochlear implanted patients divided into two groups. One group underwent auditory training in a noisy environment at home for 2 months (G1) while the other group served as a control (G0). A test of intelligibility performance in noise was conducted at inclusion and two months later. Results 52 patients were included in the study. The trained group, G1, showed a significant improvement with an increase of 4.8 dB in signal-to-noise ratio (SNR) between the two tests (P < 0.01). There was no significant improvement in the control group (G0) (P = 0.756). Conclusions This study demonstrated a significantly positive impact of personalized auditory training in a noisy environment for cochlear implant patients.

Virtual reality games for spatial hearing training in children and young people with bilateral cochlear implants: the "Both Ears (BEARS)" approach.

Spatial hearing relies on the encoding of perceptual sound location cues in space. It is critical for communicating in background noise, and understanding where sounds are coming from (sound localization). Although there are some monoaural spatial hearing cues (i.e., from one ear), most of our spatial hearing skills require binaural hearing (i.e., from two ears). Cochlear implants (CIs) are often the most appropriate rehabilitation for individuals with severe-to-profound hearing loss, with those aged 18 years of age and younger typically receiving bilateral implants (one in each ear). As experience with bilateral hearing increases, individuals tend to improve their spatial hearing skills. Extensive research demonstrates that training can enhance sound localization, speech understanding in noise, and music perception. The BEARS (Both Ears) approach utilizes Virtual Reality (VR) games specifically designed for young people with bilateral CIs to train and improve spatial hearing skills. This paper outlines the BEARS approach by: (i) emphasizing the need for more robust and engaging rehabilitation techniques, (ii) presenting the BEARS logic model that underpins the intervention, and (iii) detailing the assessment tools that will be employed in a clinical trial to evaluate the effectiveness of BEARS in alignment with the logic model.

Quality of life improvement in Cochlear implant outpatients: a non-randomized clinical trial of an auditory music training program

Objective Research on Cochlear implant (CI) outcomes has been mainly focused on verbal communication, whereas music perception has been less extensively explored. This study evaluated a music rehabilitation program, based on the mobile phone app Meludia (Meludia, France) to improve quality of life (QoL) and verbal perception in CI patients. Design In this non-randomised clinical trial, the experimental group underwent 16 Meludia sessions, while controls did not receive any music-specific rehabilitation. Patient-reported outcome (PRO) measures, including the MUSQUAV questionnaire and NCIQ domains, were utilised alongside Matrix speech perception tests (which measure speech understanding in noise). Study sample Forty patients with CI were considered: experimental group (21 patients) and control group (19 patients). Results Significant improvements (p = 0.017, and p < 0.001) in music-related PRO (MUSQUAV), and general CI PRO measures (NCIQ), respectively, were found in the experimental group. No significant differences were found in Matrix speech perception tests post-rehabilitation. Overall, 57% of participants in the experimental group reported subjective improvements in music perception. Conclusions This study showed the potential of home-based music rehabilitation in enhancing QoL for CI patients, supporting the possibility of implementing specific musical training programs in audiological care. Larger, randomised, controlled trials are necessary for further characterisation of this topic.

Active piezoelectric bone conduction implant Osia® 2 - evaluation of surgery and one-year audiological and quality of life benefits.

To present the surgical outcomes and one-year audiological and quality of life results of implantation of the Osia®2 active piezoelectric bone conduction implant. Twenty adults with mixed and conductive hearing loss were implanted with the Osia® 2 system and followed up for at least one year. The surgical course, healing, and soft tissue condition were assessed. Audiometric tests included pure tone audiometry, speech audiometry and direct bone conduction measurements. Participants completed the APHAB and SSQ questionnaires. All surgeries were successful. No soft tissue problems were observed. Pure tone audiometry showed a mean functional gain of 47.4 ± 5.6 dB HL (p = 0.000089). The Polish Monosyllabic Word Test showed mean improvements for silent, medium and loud speech of 59.5 ± 1.8%, 46.5 ± 32.3% and 13.3 ± 20.9% in quiet and 38.5 ± 24.4%, 62.0 ± 9.1%, and 36.5 ± 34.4% in noise (all p < 0.05). The Polish Matrix Test indicated a mean SNR improvement of 8.78 ± 2.31 dB SPL (p = 0.000155). BC in situ measurements were significantly better post-implantation compared to preoperative levels with Baha®6Max on the Softband. APHAB scores showed significant improvements in global, ease of communication, background noise and reverberation scores (all p < 0.001). SSQ scores improved significantly in speech, spatial and quality subscales (all p < 0.000001). The Osia®2 implantation is an effective treatment for patients with mixed and conductive hearing loss. The surgery is relatively easy and safe, with no significant postoperative or magnet pressure-related complications. Osia®2 significantly improves speech understanding in noise and reduces communication problems.

Clinical Outcomes for Adult Single-Sided Deafness Cochlear Implantees Exceeding the 5% Candidacy Criterion.

While single-sided deafness cochlear implants (SSD-CIs) have now received regulatory approval in the United States, candidate-ear candidacy criteria (no better than 5% word-recognition score) are stricter than for traditional CI candidates (50 to 60% speech recognition, best-aided condition). SSD implantation in our center began before regulatory approval, using a criterion derived from traditional candidacy: 50% consonant-nucleus-consonant (CNC) word-identification score in the candidate ear. A retrospective analysis investigated whether SSD patients exceeding the 5% CNC criterion nevertheless benefitted from a CI as assessed by spatial-hearing tests (speech understanding in noise [SIN] and localization) and by a patient-reported outcome measure quality-of-life instrument validated for patients with CIs. A retrospective chart review assessed the clinical experience of a single CI center. Subjects consisted of 27 adult CI recipients with SSD (N = 21) or asymmetric hearing loss (AHL; N = 6) implanted since September 2019 with at least 3 months of postoperative follow-up. Patients with revision surgery or simultaneous labyrinthectomy and CI surgery were excluded from the sample. Subjects were divided into 2 groups based on preoperative CNC scores measured under best-aided conditions with a behind-the-ear hearing aid in the sound field at 0.9 m from a front loudspeaker, and the better ear masked using an insert earphone with 45 dB HL speech-weighted noise. The "MEETS" group had preoperative CNC word scores <5%; the "EXCEEDS" group had scores >5%. The clinical protocol also included intelligibility tests using AzBio sentences in the same test conditions as CNC; binaural spatial testing (broadband-noise sound localization, and matrix-sentence speech-reception thresholds in spatially separated noise) using a custom-built 7-speaker array; and the CI Quality of Life (CIQOL) instrument. To evaluate CI benefit, preoperative unaided performance was compared with postoperative binaural (acoustic ear + CI ear) performance at a clinic visit closest to 6 months postsurgery. Of 27 SSD-CI recipients, 11 subjects exceeded the 5% preoperative CNC candidacy criterion. Both the MEETS and EXCEEDS groups improved significantly on all 5 primary study outcome measures (CI-alone CNC and AzBio, binaural SIN and sound localization, and CIQOL). The only statistically significant differences observed between the MEETS and EXCEEDS groups were that preoperative CNC and AzBio scores were significantly higher for the EXCEEDS group, as expected given that the groups were defined based on preoperative speech-perception scores in quiet. There were no statistically significant differences between the MEETS and EXCEEDS groups in postoperative scores in any test or in the magnitude of the improvement from preoperative to postoperative assessment. SSD- and AHL-CI recipients exceeding the 5% CNC preoperative candidacy criterion significantly improved in CI-alone speech perception, spatial hearing, and subjectively reported CIQOL outcomes and the observed benefits were indistinguishable from SSD- and AHL-CI recipients who met the 5% criterion. A less-restrictive SSD-CI and AHL-CI candidacy criterion should be considered, and larger-scale clinical trials to evaluate CI efficacy using a less-stringent candidate-ear criterion are warranted.

Hearing Aid apps: are they safe, practical and beneficial for children and teens in challenging situations?

An adult version of an app giving users the control over the level of the volume, microphone directionality and noise reduction was adapted for children. The main purpose of this study was to evaluate the effect of changes made to microphone directionality and noise reduction in the myPhonak Junior (the app) on Speech intelligibility in challenging listening environments in children and teens. The randomized, non-blinded interventional study with a single group of subjects involved two study visits with a home trial in-between. In the final study session speech assessment in noise was conducted in three different, randomly assigned conditions: default mode (Autosense Sky OS), preffered (self-adjusted) and the extreme condition. Questionnaire based assessment was conducted to assess the subjective benefit of using the app in different daily situations. The best scores (speech results in noise) were achieved with the preferred setting and the default Autosense Sky OS setting was significantly better than the extreme setting. The self-reported benefit through the questionnaire indicates significantly better result when adjusting the hearing aids through the app. The app is an easy-to-use way of controlling the level of noise reduction and the beam forming for children 11 years and older. It has the potential to help customizing the hearing aids beyond the default setting and helping to improve speech understanding in noise.

Predictors of Speech-in-Noise Understanding in a Population of Occupationally Noise-Exposed Individuals.

Understanding speech in noise is particularly difficult for individuals occupationally exposed to noise due to a mix of noise-induced auditory lesions and the energetic masking of speech signals. For years, the monitoring of conventional audiometric thresholds has been the usual method to check and preserve auditory function. Recently, suprathreshold deficits, notably, difficulties in understanding speech in noise, has pointed out the need for new monitoring tools. The present study aims to identify the most important variables that predict speech in noise understanding in order to suggest a new method of hearing status monitoring. Physiological (distortion products of otoacoustic emissions, electrocochleography) and behavioral (amplitude and frequency modulation detection thresholds, conventional and extended high-frequency audiometric thresholds) variables were collected in a population of individuals presenting a relatively homogeneous occupational noise exposure. Those variables were used as predictors in a statistical model (random forest) to predict the scores of three different speech-in-noise tests and a self-report of speech-in-noise ability. The extended high-frequency threshold appears to be the best predictor and therefore an interesting candidate for a new way of monitoring noise-exposed professionals.

The Output Signal-to-Noise Ratio and Speech Perception in Noise: The Effect of Multichannel and Free-Channel Hearing Aids

Background and Aim: The output Signal-to-Noise Ratio (SNR) is one of the essential factors in hearing aid benefits. There is limited evidence regarding SNR improvement by the Channel-Free (CFHA) and Multi-Channel Hearing Aid (MCHA) and the speech understanding in noise through them. This study aimed to investigate the extent to which output SNR was modified by CFHA and MCHA processing and the variation in aided speech recognition abilities with a change in output SNR. Methods: Thirty-six participants aged 50–65 years were included. A chosen CFHA and MCHA were used to obtain the output SNR and sentence recognition in noise in four different processing algorithms (linear, linear+noise reduction, WDRC, WDRC+noise reduction). Hagerman’s phase inversion technique was used to measure the attenuation of noise and, in turn, to obtain the output SNR of the hearing aid. Results: In all hearing aid processing algorithms among those with normal hearing and people with hearing loss, the output of CFHA revealed higher attenuation values than that of MCHA. There was a significant effect of the hearing aids and processing algorithms in both normal and individuals with hearing impairment on the mean SNR. Further, multiple linear regression analysis results showed that whether the hearing is channel-free or multi- channel significantly predicted speech recognition scores, while output SNR and processing algorithms did not. Conclusion: The signal processing algorithms in CFHA had greater noise attenuation values, better output SNR, and speech recognition scores, showing an advantage over the modern MCHA among individuals with hearing impairment. Keywords: Channel-free hearing aids; multi-channel hearing aids; sensorineural hearing loss; speech recognition

Speech Comprehension by Cochlear Implant Users Assessed with Evoked Potentials and Response Times

Introduction: Cochlear implant (CI) users differ greatly in their rehabilitation outcomes, including speech understanding in noise. This variability may be related to brain changes associated with intact senses recruiting cortical areas from stimulation-deprived senses. Numerous studies have demonstrated such cross-modal reorganization in individuals with untreated hearing loss. How it is affected by regular use of hearing devices remains unclear, however. To shed light on this, the current study measured cortical responses reflecting comprehension abilities in experienced CI users and normal-hearing controls. Methods: Using multichannel electroencephalography, we tested CI users who had used their devices for at least 12 months and closely matched controls (N = 2 × 13). Cortical responses reflecting comprehension abilities – the N400 and late positive complex (LPC) components – were evoked using congruent and incongruent digit-triplet stimuli. The participants’ task was to assess digit-triplet congruency by means of timed button presses. All measurements were performed in speech-shaped noise 15 dB above individually measured speech recognition thresholds. Three stimulus presentation modes were used: auditory-only, visual-only, and visual-then-auditory. Results: The analyses revealed no group differences in the N400 and LPC responses. In terms of response times, the CI users were slower and differentially affected by the three stimulus presentation modes relative to the controls. Conclusion: Compared to normal-hearing controls, experienced CI users may need more time to comprehend speech in noise. Response times can serve as a proxy for speech comprehension by CI users.

The Benefit of Bimodal Hearing and Beamforming for Cochlear Implant Users

Plain Language SummaryCochlear implantation is the standard treatment for severe to profound hearing loss. While cochlear implant (CI) users can communicate effectively in quiet environments, speech understanding in noise remains challenging. Bimodal hearing, combining a CI in one ear and a hearing aid (HA) in the other, has shown advantages over unilateral electrical hearing, especially for speech understanding in noisy conditions. We analyzed the effect of the addition of the HA to the CI in this paper. There are also other processing techniques available to improve speech understanding in noise for this population. In this paper, one of these techniques, beamforming, is studied in different configurations. Therefore, 17 participants with a CI in one ear and a HA in the other ear are included. They performed a speech test for different configurations with and without beamforming to be able to analyze the effect of beamforming.

Speech-in-Noise Assessment in the Routine Audiologic Test Battery: Relationship to Perceived Auditory Disability.

Self-assessment of perceived communication difficulty has been used in clinical and research practices for decades. Such questionnaires routinely assess the perceived ability of an individual to understand speech, particularly in background noise. Despite the emphasis on perceived performance in noise, speech recognition in routine audiologic practice is measured by word recognition in quiet (WRQ). Moreover, surprisingly little data exist that compare speech understanding in noise (SIN) abilities to perceived communication difficulty. Here, we address these issues by examining audiometric thresholds, WRQ scores, QuickSIN signal to noise ratio (SNR) loss, and perceived auditory disability as measured by the five questions on the Speech Spatial Questionnaire-12 (SSQ12) devoted to speech understanding (SSQ12-Speech5). We examined data from 1633 patients who underwent audiometric assessment at the Stanford Ear Institute. All individuals completed the SSQ12 questionnaire, pure-tone audiometry, and speech assessment consisting of ear-specific WRQ, and ear-specific QuickSIN. Only individuals with hearing threshold asymmetries ≤10 dB HL in their high-frequency pure-tone average (HFPTA) were included. Our primary objectives were to (1) examine the relationship between audiometric variables and the SSQ12-Speech5 scores, (2) determine the amount of variance in the SSQ12-Speech5 scores which could be predicted from audiometric variables, and (3) predict which patients were likely to report greater perceived auditory disability according to the SSQ12-Speech5. Performance on the SSQ12-Speech5 indicated greater perceived auditory disability with more severe degrees of hearing loss and greater QuickSIN SNR loss. Degree of hearing loss and QuickSIN SNR loss were found to account for modest but significant variance in SSQ12-Speech5 scores after accounting for age. In contrast, WRQ scores did not significantly contribute to the predictive power of the model. Degree of hearing loss and QuickSIN SNR loss were also found to have moderate diagnostic accuracy for determining which patients were likely to report SSQ12-Speech5 scores indicating greater perceived auditory disability. Taken together, these data indicate that audiometric factors including degree of hearing loss (i.e., HFPTA) and QuickSIN SNR loss are predictive of SSQ12-Speech5 scores, though notable variance remains unaccounted for after considering these factors. HFPTA and QuickSIN SNR loss-but not WRQ scores-accounted for a significant amount of variance in SSQ12-Speech5 scores and were largely effective at predicting which patients are likely to report greater perceived auditory disability on the SSQ12-Speech5. This provides further evidence for the notion that speech-in-noise measures have greater clinical utility than WRQ in most instances as they relate more closely to measures of perceived auditory disability.

Masked Speech Perception with Bone Conduction Device, Contralateral Routing of Signals Hearing Aid, and Cochlear Implant Use in Adults with Single-Sided Deafness: A Prospective Hearing Device Comparison using a Unified Testing Framework

Introduction: For the treatment of single-sided deafness (SSD), common treatment choices include a contralateral routing of signals (CROS) hearing aid, a bone conduction device (BCD), and a cochlear implant (CI). The primary aim of this study was to compare speech understanding in noise and binaural benefits in adults with postlingual SSD between preoperative unaided baseline, preoperative CROS and BCD trial devices, and CI, following recommendations from a consensus protocol. In addition, we investigated the effect of masker type on speech understanding. Methods: This was a prospective study with twelve participants. Binaural effects of head shadow, squelch, summation, and spatial release from masking were assessed by measuring speech reception thresholds (SRTs) in five different spatial target-masker configurations using two different maskers: two-talker babble (TTB), and speech-shaped noise (SSN). Preoperatively, participants were assessed unaided and with CROS and BCD trial devices. After cochlear implantation, participants were assessed at 1, 3, and 6 months post-activation. Results: For TTB, significant improvements in SRT with a CI relative to preoperatively unaided were found in all spatial configurations. With CI at 6 months, median benefits were 7.8 dB in SSSDNAH and 5.1 dB in S0NAH (head shadow), 3.4 dB in S0N0 (summation), and 4.6 dB in S0NSSD and 5.1 dB in SAHNSSD (squelch). CROS yielded a significant head shadow benefit of 2.4 dB in SSSDNAH and a significant deterioration in squelch of 2.5 dB in S0NSSD and SAHNSSD, but no summation effect. With BCD, there was a significant summation benefit of 1.5 dB, but no head shadow nor squelch effect. For SSN, significant improvements in SRT with CI compared to preoperatively unaided were found in three spatial configurations. Median benefits with CI at 6 months were: 8.5 dB in SSSDNAH and 4.6 dB in S0NAH (head shadow), 1.4 dB in S0N0 (summation), but no squelch. CROS showed a significant head shadow benefit of 1.7 dB in SSSDNAH, but no summation effect, and a significant deterioration in squelch of 2.9 dB in S0NSSD and 3.2 dB in SAHNSSD. With BCD, no binaural effect was obtained. Longitudinally, we found significant head shadow benefits with a CI in SSSDNAH in both maskers at all postoperative intervals and in S0NAH at 3 and 6 months post-activation. Conclusion: With a CI, a clear benefit for masked speech perception was observed for all binaural effects. Benefits with CROS and BCD were more limited. CROS usage was detrimental to the squelch effect.

Speech Understanding and Subjective Listening Effort in Noise With Different OTEs and Sound Processing Technologies.

To determine speech reception thresholds (SRTs) in noise and subjective listening effort (LE) in cochlear implant (CI) recipients for application of three sound processing (SP) technologies with two off-the-ear (OTE) CI sound processors, a fixed moderately directional microphone (Standard), an adaptive directional microphone (Beam), and the spatial noise-reduction setting ForwardFocus, with the Kanso 2 (OTE2), and Beam with the Kanso (OTE1). Prospective repeated measures, within-subject design. Single tertiary-referral center. Twenty CI recipients with bilateral severe-to-profound sensorineural hearing loss. SRTs were assessed in two spatial configurations with frontal speech and noise from 90-180-270 degrees (S0N90-180-270) or from the CI side (S0NCI). SRTs were obtained for sentences of the Oldenburg sentence test presented in International Collegium of Rehabilitative Audiology (ICRA) noise ICRA5-250. LE for speech understanding in noise was evaluated in S0N90-180-270 and assessed in effort scale categorical units (ESCUs) by using Adaptive Categorical Listening Effort Scaling (ACALES). LEs at 5-dB signal-to-noise ratio (SNR) were calculated from fitted psychometric curves. With OTE2 in S0N90-180-270, SRT with ForwardFocus (-4.28 dB SNR) was better than with Beam (-3.13 dB SNR) and Standard (0.43 dB SNR). ForwardFocus showed lower LE5dB (2.61 ESCU) compared with Beam (4.60 ESCU) and Standard (5.32 ESCU). In a comparison of both OTEs in S0N90-180-270 regarding best-performing SP technology, ForwardFocus with OTE2 yielded a better SRT and better LE5dB than Beam with OTE1 (SRT: -1.70 dB SNR; LE5dB: 4.00 ESCU). With OTE2 in S0NCI, SRT was improved with ForwardFocus (-2.78 dB SNR) compared with Beam (-1.23 dB SNR) and Standard (1.83 dB SNR). With respect to SP technology and OTE, CI recipients experience best SRT and lowest LE in S0N90-180-270 when using ForwardFocus with OTE2. ACALES is feasible for assessing subjective LE in CI recipients.

Review of Binaural Processing With Asymmetrical Hearing Outcomes in Patients With Bilateral Cochlear Implants.

Bilateral cochlear implants (BiCIs) result in several benefits, including improvements in speech understanding in noise and sound source localization. However, the benefit bilateral implants provide among recipients varies considerably across individuals. Here we consider one of the reasons for this variability: difference in hearing function between the two ears, that is, interaural asymmetry. Thus far, investigations of interaural asymmetry have been highly specialized within various research areas. The goal of this review is to integrate these studies in one place, motivating future research in the area of interaural asymmetry. We first consider bottom-up processing, where binaural cues are represented using excitation-inhibition of signals from the left ear and right ear, varying with the location of the sound in space, and represented by the lateral superior olive in the auditory brainstem. We then consider top-down processing via predictive coding, which assumes that perception stems from expectations based on context and prior sensory experience, represented by cascading series of cortical circuits. An internal, perceptual model is maintained and updated in light of incoming sensory input. Together, we hope that this amalgamation of physiological, behavioral, and modeling studies will help bridge gaps in the field of binaural hearing and promote a clearer understanding of the implications of interaural asymmetry for future research on optimal patient interventions.

Comprehensive behavioral and physiologic assessment of peripheral and central auditory function in individuals with mild traumatic brain injury

Auditory complaints are frequently reported by individuals with mild traumatic brain injury (mTBI) yet remain difficult to detect in the absence of clinically significant hearing loss. This highlights a growing need to identify sensitive indices of auditory-related mTBI pathophysiology beyond pure-tone thresholds for improved hearing healthcare diagnosis and treatment. Given the heterogeneity of mTBI etiology and the diverse peripheral and central processes required for normal auditory function, the present study sought to determine the audiologic assessments sensitive to mTBI pathophysiology at the group level using a well-rounded test battery of both peripheral and central auditory system function. This test battery included pure-tone detection thresholds, word understanding in quiet, sentence understanding in noise, distortion product otoacoustic emissions (DPOAEs), middle-ear muscle reflexes (MEMRs), and auditory evoked potentials (AEPs), including auditory brainstem responses (ABRs), middle latency responses (MLRs), and late latency responses (LLRs). Each participant also received magnetic resonance imaging (MRI). Compared to the control group, we found that individuals with mTBI had reduced DPOAE amplitudes that revealed a compound effect of age, elevated MEMR thresholds for an ipsilateral broadband noise elicitor, longer ABR Wave I latencies for click and 4 kHz tone burst elicitors, longer ABR Wave III latencies for 4 kHz tone bursts, larger MLR Na and Nb amplitudes, smaller MLR Pb amplitudes, longer MLR Pa latencies, and smaller LLR N1 amplitudes for older individuals with mTBI. Further, mTBI individuals with combined hearing difficulty and noise sensitivity had a greater number of deficits on thalamic and cortical AEP measures compared to those with only one/no self-reported auditory symptoms. This finding was corroborated with MRI, which revealed significant structural differences in the auditory cortical areas of mTBI participants who reported combined hearing difficulty and noise sensitivity, including an enlargement of left transverse temporal gyrus (TTG) and bilateral planum polare (PP). These findings highlight the need for continued investigations toward identifying individualized audiologic assessments and treatments that are sensitive to mTBI pathophysiology.

Behavioral characterization of the cochlear amplifier lesion due to loss of function of stereocilin (STRC) in human subjects

Loss of function of stereocilin (STRC) is the second most common cause of inherited hearing loss. The loss of the stereocilin protein, encoded by the STRC gene, induces the loss of connection between outer hair cells and tectorial membrane. This only affects the outer hair cells (OHCs) function, involving deficits of active cochlear frequency selectivity and amplifier functions despite preservation of normal inner hair cells. Better understanding of cochlear features associated with mutation of STRC will improve our knowledge of normal cochlear function, the pathophysiology of hearing impairment, and potentially enhance hearing aid and cochlear implant signal processing. Nine subjects with homozygous or compound heterozygous loss of function mutations in STRC were included, age 7–24 years. Temporal and spectral modulation perception were measured, characterized by spectral and temporal modulation transfer functions. Speech-in-noise perception was studied with spondee identification in adaptive steady-state noise and AzBio sentences with 0 and -5 dB SNR multitalker babble. Results were compared with normal hearing (NH) and cochlear implant (CI) listeners to place STRC−/− listeners’ hearing capacity in context. Spectral ripple discrimination thresholds in the STRC−/− subjects were poorer than in NH listeners (p < 0.0001) but remained better than for CI listeners (p < 0.0001). Frequency resolution appeared impaired in the STRC−/− group compared to NH listeners but did not reach statistical significance (p = 0.06). Compared to NH listeners, amplitude modulation detection thresholds in the STRC−/− group did not reach significance (p= 0.06) but were better than in CI subjects (p < 0.0001). Temporal resolution in STRC−/− subjects was similar to NH (p = 0.98) but better than in CI listeners (p = 0.04). The spondee reception threshold in the STRC−/− group was worse than NH listeners (p = 0.0008) but better than CI listeners (p = 0.0001). For AzBio sentences, performance at 0 dB SNR was similar between the STRC−/− group and the NH group, 88 % and 97 % respectively. For -5 dB SNR, the STRC−/− performance was significantly poorer than NH, 40 % and 85 % respectively, yet much better than with CI who performed at 54 % at +5 dB SNR in children and 53 % at + 10 dB SNR in adults. To our knowledge, this is the first study of the psychoacoustic performance of human subjects lacking cochlear amplification but with normal inner hair cell function. Our data demonstrate preservation of temporal resolution and a trend to impaired frequency resolution in this group without reaching statistical significance. Speech-in-noise perception compared to NH listeners was impaired as well. All measures were better than those in CI listeners. It remains to be seen if hearing aid modifications, customized for the spectral deficits in STRC−/− listeners can improve speech understanding in noise. Since cochlear implants are also limited by deficient spectral selectivity, STRC−/− hearing may provide an upper bound on what could be obtained with better temporal coding in electrical stimulation.

A Transparent Mask and Clear Speech Benefit Speech Intelligibility in Individuals With Hearing Loss.

The purpose of the study is to investigate the impacts of a surgical mask and a transparent mask on audio-only and audiovisual speech intelligibility in noise (i.e., 0 dB signal-to-noise ratio) in individuals with mild-to-profound hearing loss. The study also examined if individuals with hearing loss can benefit from using a transparent mask and clear speech for speech understanding in noise. Thirty-one individuals with hearing loss (from 22 to 74 years old) completed keyword identification tasks to measure face-masked speech intelligibility in noise. A mixed-effects logistic regression model was used to examine the effects of face masks (no mask, transparent mask, surgical mask), presentation modes (audio only, audiovisual), speaking styles (conversational, clear), noise type (speech-shaped noise [SSN], four-talker babble [4-T babble]), hearing groups (mild hearing loss [MHL], greater than MHL: GHL), and their interactions on binary accuracy of keyword identification. In the audio-only mode, the GHL group showed reduced speech intelligibility regardless of other factors, whereas the MHL group showed decreased speech intelligibility for the transparent mask more than for the surgical mask. The use of a transparent mask was advantageous for both hearing loss groups. Clear speech remediated the detrimental effects of face masks on speech intelligibility in noise. Both groups tended to perform better in SSN versus 4-T babble. The findings indicate that, when using face masks, either a transparent mask or a surgical mask negatively affects speech understanding in noise for individuals with hearing loss. Using a transparent mask and clear speech could be a potential solution to improve speech intelligibility in communication with face masks in noise.

A comparison of binaural cues transmitted by clinically available cochlear-implant stimulation strategies

Cochlear implants (Cis) effectively restore speech understanding in quiet for many recipients. However, bilateral CI listeners continue to perform poorer than acoustic-hearing listeners on spatial-hearing tasks (e.g., speech understanding in noise and sound localization). One explanation is that current clinically available stimulation strategies and unsynchronized sound processors degrade the fidelity of binaural cues. However, no conclusive comparison of the binaural cues transmitted by different stimulation strategies has been made. Therefore, this study compared binaural cues transmitted by two clinically available cochlear implant stimulation strategies. Two unsynchronized Cochlear Ltd. Nucleus 6 sound processors were placed on a binaural mannequin centered in a horizontal ring of loudspeakers in an anechoic chamber. Acoustic stimuli were presented from the loudspeakers and the resulting electrical pulse trains were recorded for both a peak-picking stimulation strategy and constantly stimulating strategy. Envelope interaural time differences and interaural level differences were extracted from the recordings and compared between stimulation strategies. Compared to the constantly stimulating strategy, results show that the peak-picking strategy led to more variable and less monotonic binaural cues, which could constrain sound-localization abilities. These findings argue for the bilateral synchronization of CIs in multiple domains, including electrode selection in peak-picking stimulation strategies and pulse timing.

Listening to the room: Disrupting activity of dorsolateral prefrontal cortex impairs learning of room acoustics

Navigating complex sensory environments is critical to survival, and brain mechanisms have evolved to cope with the wide range of surroundings. In noisy spaces listeners place more emphasis on early-arriving sound energy, nevertheless, reverberant energy is highly informative about those spaces per se, and human listeners show improved speech understanding when re-encountering known reverberant environments. We assessed the ability of listeners to perceive speech (Coordinate Response Measure corpus) in noisy and reverberant rooms. We mimicked the acoustic characteristics of real rooms using loudspeakers positioned within an anechoic chamber. Listeners were also exposed to repetitive transcranial stimulation (rTMS) to disrupt the dorsolateral prefrontal cortex activity (DLFPC), a region believed to play a role in statistical learning. Our data suggest listeners rapidly adapt to statistical characteristics of an acoustic environment to improve speech understanding. This ability is impaired when rTMS is applied bilaterally to the DLPFC. The data demonstrate that speech understanding in noise is best when exposed to a room with reverberant characteristics common to human-built environments. Our findings provide evidence for a reverberation “sweet spot” and the presence of brain mechanisms that might have evolved to cope with the acoustic characteristics of listening environments encountered every day.

Speech understanding in noise for cochlear implant recipients using a spatial noise reduction setting in an off the ear sound processor with directional microphones

Purpose Cochlear implant (CI) recipients struggle to hear in competing background noise. ForwardFocus is a spatial noise reduction setting from Cochlear Ltd. (Sydney) that can simultaneously attenuate noise from multiple sources behind the listener. This study assessed hearing performance with ForwardFocus in an off-the-ear (OTE) sound processor. Method Twenty-two experienced adult CI recipients participated. Speech reception data was collected in fixed noise acutely in the clinic. After three to five weeks take home experience, subjective impressions were recorded, and evaluations were conducted for speech reception in quiet and roving noise. Results Group mean speech reception thresholds (SRT) were below 0 dB in two spatially-separated noise test conditions when using ForwardFocus in the OTE sound processor. SRT were −8.5 dB (SD 2.9) in 4-talker babble roving in a rear hemi-field (S0Nrearhemi) and −3.9 dB (SD 3.3) in 12-talker babble presented laterally and behind (S0N3). Results in S0N3 were significantly better with ForwardFocus On (p = 0.0018). Subjective ratings with the OTE were comparable to, or better than, with their walk-in BTE or OTE sound processor. Conclusions ForwardFocus provides significant benefits for speech recognition in competing background noise in an OTE sound processor. These results support clinicians in counselling CI recipients on potential sound processor options to consider.