Speech Reception In Noise Research Articles

Investigating the Utility of a Compact Loudspeaker Array for Audiometric Testing.

This project addressed the uses of a loudspeaker array for audiometric measurements. It sought to evaluate a prototype compact array in terms of the reliability of test results across sound booths. A seven-loudspeaker array was developed to deliver sounds from -60° to +60° on an arc with a radius of 0.5 m. The system was equipped with a head position sensing system to maintain the listener's head near the optimal test position. Three array systems were distributed to each of the two test sites for within-subject assessments of booth equivalence on tests of sound localization, speech reception in noise, and threshold detection. A total of 36 subjects participated, 18 at each test site. Results showed excellent interbooth consistency on tests of sound localization using speech and noise signals, including conditions in which one or both ears were covered with a muff. Booth consistency was also excellent on sound field threshold measurements for detecting quasi-diffuse noise bands. Nonequivalence was observed in some cases of speech-in-noise tests, particularly with a small one-person booth. Acoustic analyses of in situ loudspeaker responses indicated that some of the nonequivalent comparisons on speech-in-noise tests could be traced to the effects of reflections. Overall, the results demonstrate the utility and reliability of a compact array for the assessment of localization ability, speech reception in noise, and sound field thresholds. However, the results indicate that researchers and clinicians should be aware of the reflection effects that can influence the results of sound field tests in which signal and noise levels from separate loudspeakers are critical.

Computational Modeling of Synchrony in the Auditory Nerve in Response to Acoustic and Electric Stimulation.

Cochlear implants are medical devices that provide hearing to nearly one million people around the world. Outcomes are impressive with most recipients learning to understand speech through this new way of hearing. Music perception and speech reception in noise, however, are notably poor. These aspects of hearing critically depend on sensitivity to pitch, whether the musical pitch of an instrument or the vocal pitch of speech. The present article examines cues for pitch perception in the auditory nerve based on computational models. Modeled neural synchrony for pure and complex tones is examined for three different electric stimulation strategies including Continuous Interleaved Sampling (CIS), High-Fidelity CIS (HDCIS), and Peak-Derived Timing (PDT). Computational modeling of current spread and neuronal response are used to predict neural activity to electric and acoustic stimulation. It is shown that CIS does not provide neural synchrony to the frequency of pure tones nor to the fundamental component of complex tones. The newer HDCIS and PDT strategies restore synchrony to both the frequency of pure tones and to the fundamental component of complex tones. Current spread reduces spatial specificity of excitation as well as the temporal fidelity of neural synchrony, but modeled neural excitation restores precision of these cues. Overall, modeled neural excitation to electric stimulation that incorporates temporal fine structure (e.g., HDCIS and PDT) indicates neural synchrony comparable to that provided by acoustic stimulation. Discussion considers the importance of stimulation rate and long-term rehabilitation to provide temporal cues for pitch perception.

Acoustic analysis of the effect of personal protective equipment on speech understanding: lessons for clinical environments

Objective The use of various types of filtering facepiece class 3 (FFP3) mask have become commonplace since the Covid-19 outbreak. These have been evaluated in terms of efficacy regarding aerosol filtration but less emphasis has been placed on the acoustic effects of such masks and their consequences for clinical communication. Design A microphone 65 cm from a sound-producing Head and Torso Simulator (wearing the masks) was used to measure attenuation via a tone sweep. Predicted impact on speech reception in noise was assessed by weighting the attenuations of cochlear excitation patterns by the frequency importance function of the Speech Intelligibility Index. Study sample We evaluated acoustic attenuation properties of seven FFP3 masks and a Type IIR surgical mask (as a comparator). Results The Type IIR mask had the smallest impact on SNR (2.6 dB with visor). Most FFP3s with an addition of a visor (if not already face covering) impacted SNR by approximately 6 dB. The 3 M 6000 was significantly worse (15.8 dB). Conclusions Mouth-and-nose covering FFP3s masks had similar effects on SNR (≈6.2 dB with visor). The Tecmen TM-H2 had several advantages over other masks evaluated. It was reusable, allowed lipreading clues and the attenuation was similar to other FFP3s.

Chronic Bilateral Cochlear Implant Stimulation Partially Restores Neural Binaural Sensitivity in Neonatally-Deaf Rabbits.

Cochlear implant (CI) users with a prelingual onset of hearing loss show poor sensitivity to interaural time differences (ITDs), an important cue for sound localization and speech reception in noise. Similarly, neural ITD sensitivity in the inferior colliculus (IC) of neonatally-deafened animals is degraded compared with animals deafened as adults. Here, we show that chronic bilateral CI stimulation during development can partly reverse the effect of early-onset deafness on ITD sensitivity. The prevalence of ITD sensitive neurons was restored to the level of adult-deaf (AD) rabbits in the early-deaf rabbits of both sexes that received chronic stimulation and behavioral training with wearable bilateral sound processors during development. We also found a partial improvement in neural ITD sensitivity in the early-deaf and stimulated rabbits compared with unstimulated rabbits. In contrast, chronic CI stimulation did not improve temporal coding in early-deaf rabbits. The present study is the first report showing functional restoration of ITD sensitivity with CI stimulation in single neurons and highlights the importance of auditory experience during development on the maturation of binaural circuitry.SIGNIFICANCE STATEMENT Although cochlear implants (CI) are highly successful in providing speech reception in quiet for many profoundly deaf people, CI users still face difficulty in noisy everyday environment. This is partly because of their poor sensitivity to differences in the timing of sounds arriving at the two ears [interaural time differences (ITDs)], which help to identify where the sound is coming from. This problem is especially acute in those who lost hearing early in life. Here, we present the first report that sensitivity of auditory neurons to ITDs is restored by CI stimulation during development in an animal model of neonatal deafness. These findings highlight the importance of providing early binaural auditory experience with CIs in deaf children.

Effects of age on psychophysical measures of auditory temporal processing and speech reception at low and high levels

Age-related cochlear synaptopathy (CS) has been shown to occur in rodents with minimal noise exposure, and has been hypothesized to play a crucial role in age-related hearing declines in humans. It is not known to what extent age-related CS occurs in humans, and how it affects the coding of supra-threshold sounds and speech in noise. Because in rodents CS affects mainly low- and medium-spontaneous rate (L/M-SR) auditory-nerve fibers with rate-level functions covering medium-high levels, it should lead to greater deficits in the processing of sounds at high than at low stimulus levels. In this cross-sectional study the performance of 102 listeners across the age range (34 young, 34 middle-aged, 34 older) was assessed in a set of psychophysical temporal processing and speech reception in noise tests at both low, and high stimulus levels. Mixed-effect multiple regression models were used to estimate the effects of age while partialing out effects of audiometric thresholds, lifetime noise exposure, cognitive abilities (assessed with additional tests), and musical experience. Age was independently associated with performance deficits on several tests. However, only for one out of 13 tests were age effects credibly larger at the high compared to the low stimulus level. Overall these results do not provide much evidence that age-related CS, to the extent to which it may occur in humans according to the rodent model of greater L/M-SR synaptic loss, has substantial effects on psychophysical measures of auditory temporal processing or on speech reception in noise.

Benefits from different types of acoustic beamforming in bilateral cochlear-implant listeners

Acoustic beamforming improves speech reception in noise at the cost of removing spatial cues. Recently, novel approaches have been proposed for enhancing speech reception via beamforming while preserving sound localization by reintroducing natural binaural cues to the beamformer output. It is, however, unclear whether such a hybrid approach will improve performance for bilateral cochlear-implant (BICI) listeners because they receive little benefit from natural spatial cues. Here, effects of beamforming on masked speech reception thresholds (SRTs) were determined in BICI and normal-hearing (NH) listeners for a standard single-channel beamformer and a new triple-beamformer comprising a diotic central beam, -40 deg left-ear-only beam, and + 40 deg right-ear-only beam [Jennings and Kidd, JASA 143, 1743]. Speech targets and maskers were co-located (0 deg) or maskers were symmetrically separated at ±30 deg or ±90 deg. Natural binaural listening, single-channel beamformer, and triple-beamformer conditions were tested. Both beamformers were better than natural cues. For BICI listeners, single-channel beamforming improved SRTs by 5 (±30 deg) and 15 dB (±90 deg). SRTs for the triple-beam were best for NH but were 5 dB worse than the single-channel beam for BICI listeners. These preliminary findings suggest beamforming provides significant spatial release from masking for BICI listeners but assessing overall benefit, including localization, awaits further study.

A method for degrading sound localization while preserving binaural advantages for speech reception in noise.

This study developed and tested a real-time processing algorithm designed to degrade sound localization (LocDeg algorithm) without affecting binaural benefits for speech reception in noise. Input signals were divided into eight frequency channels. The odd-numbered channels were mixed between the ears to confuse the direction of interaural cues while preserving interaural cues in the even-numbered channels. The LocDeg algorithm was evaluated for normal-hearing listeners performing sound localization and speech-reception tasks. Results showed that the LocDeg algorithm successfully degraded sound-localization performance without affecting speech-reception performance or spatial release from masking for speech in noise. The LocDeg algorithm did, however, degrade speech-reception performance in a task involving spatially separated talkers in a multi-talker environment, which is thought to depend on differences in perceived spatial location of concurrent talkers. This LocDeg algorithm could be a valuable tool for isolating the importance of sound-localization ability from other binaural benefits in real-world environments.

Improving Localization and Speech Reception in Noise for Bilateral Cochlear Implant Recipients.

This study looked at different methods to preserve interaural level difference (ILD) cues for bilateral cochlear implant (BiCI) recipients. One possible distortion to ILD is from automatic gain control (AGC). Localization accuracy of BiCI recipients using default versus increased AGC threshold and linked AGCs versus independent AGCs was examined. In addition, speech reception in noise was assessed using linked versus independent AGCs and enabling and disabling Autosensitivity™ Control. Subjective information via a diary and questionnaire was also collected about maps with linked and independent AGCs during a take-home experience. Localization accuracy improved in the increased AGC threshold and the linked AGCs conditions. Increasing the AGC threshold resulted in a 4° improvement in root mean square error averaged across all speaker locations. Using linked AGCs, BiCI participants experienced an 8° improvement for all speaker locations and a 19° improvement at the speaker location most affected by the AGC. Speech reception threshold in noise improved by an average of 2.5 dB when using linked AGCs versus independent AGCs. In addition, the effect of linked AGCs on speech in noise was compared with that of Autosensitivity™ Control. The Speech, Spatial, and Qualities of Hearing Scale-12 question comparative survey showed an improvement when using maps with linked AGCs. These findings support the hypothesis that ILD cues may be preserved by increasing the AGC threshold or linking AGCs.

Objective speech transmission improvements with a binaural cochlear implant sound-coding strategy inspired by the contralateral medial olivocochlear reflex.

It has been recently shown that cochlear implant users could enjoy better speech reception in noise and enhanced spatial unmasking with binaural audio processing inspired by the inhibitory effects of the contralateral medial olivocochlear (MOC) reflex on compression [Lopez-Poveda, Eustaquio-Martin, Stohl, Wolford, Schatzer, and Wilson (2016). Ear Hear. 37, e138-e148]. The perceptual evidence supporting those benefits, however, is limited to a few target-interferer spatial configurations and to a particular implementation of contralateral MOC inhibition. Here, the short-term objective intelligibility index is used to (1) objectively demonstrate potential benefits over many more spatial configurations, and (2) investigate if the predicted benefits may be enhanced by using more realistic MOC implementations. Results corroborate the advantages and drawbacks of MOC processing indicated by the previously published perceptual tests. The results also suggest that the benefits may be enhanced and the drawbacks overcome by using longer time constants for the activation and deactivation of inhibition and, to a lesser extent, by using a comparatively greater inhibition in the lower than in the higher frequency channels. Compared to using two functionally independent processors, the better MOC processor improved the signal-to-noise ratio in the two ears between 1 and 6 decibels by enhancing head-shadow effects, and was advantageous for all tested target-interferer spatial configurations.

Adaptive spatial filtering improves speech reception in noise while preserving binaural cues.

Hearing loss greatly reduces an individual's ability to comprehend speech in the presence of background noise. Over the past decades, numerous signal-processing algorithms have been developed to improve speech reception in these situations for cochlear implant and hearing aid users. One challenge is to reduce background noise while not introducing interaural distortion that would degrade binaural hearing. The present study evaluates a noise reduction algorithm, referred to as binaural Fennec, that was designed to improve speech reception in background noise while preserving binaural cues. Speech reception thresholds were measured for normal-hearing listeners in a simulated environment with target speech generated in front of the listener and background noise originating 90° to the right of the listener. Lateralization thresholds were also measured in the presence of background noise. These measures were conducted in anechoic and reverberant environments. Results indicate that the algorithm improved speech reception thresholds, even in highly reverberant environments. Results indicate that the algorithm also improved lateralization thresholds for the anechoic environment while not affecting lateralization thresholds for the reverberant environments. These results provide clear evidence that this algorithm can improve speech reception in background noise while preserving binaural cues used to lateralize sound.

Long-term use benefits of personal frequency-modulated systems for speech in noise perception in patients with stroke with auditory processing deficits: a non-randomised controlled trial study

ObjectivesApproximately one in five stroke survivors suffer from difficulties with speech reception in noise, despite normal audiometry. These deficits are treatable with personal frequency-modulated systems (FMs). This study aimed to...

On the Etiology of Listening Difficulties in Noise Despite Clinically Normal Audiograms.

Many people with difficulties following conversations in noisy settings have “clinically normal” audiograms, that is, tone thresholds better than 20 dB HL from 0.1 to 8 kHz. This review summarizes the possible causes of such difficulties, and examines established as well as promising new psychoacoustic and electrophysiologic approaches to differentiate between them. Deficits at the level of the auditory periphery are possible even if thresholds remain around 0 dB HL, and become probable when they reach 10 to 20 dB HL. Extending the audiogram beyond 8 kHz can identify early signs of noise-induced trauma to the vulnerable basal turn of the cochlea, and might point to “hidden” losses at lower frequencies that could compromise speech reception in noise. Listening difficulties can also be a consequence of impaired central auditory processing, resulting from lesions affecting the auditory brainstem or cortex, or from abnormal patterns of sound input during developmental sensitive periods and even in adulthood. Such auditory processing disorders should be distinguished from (cognitive) linguistic deficits, and from problems with attention or working memory that may not be specific to the auditory modality. Improved diagnosis of the causes of listening difficulties in noise should lead to better treatment outcomes, by optimizing auditory training procedures to the specific deficits of individual patients, for example.

Development and validation of the Speech Reception in Noise (SPRINT) Test

Since 1992, the Speech Recognition in Noise Test, or SPRINT, has been the standard speech-in-noise test for assessing auditory fitness-for-duty of US Army Soldiers with hearing loss. The original SPRINT test consisted of 200 monosyllabic words presented at a Signal-to-Noise Ratio (SNR) of +9 dB in the presence of a six-talker babble noise. Normative data for the test was collected on 319 hearing impaired Soldiers, and a procedure for making recommendations about the disposition of military personnel on the basis of their SPRINT score and their years of experience was developed and implemented as part of US Army policy. In 2013, a new 100-word version of the test was developed that eliminated words that were either too easy or too hard to make meaningful distinctions among hearing impaired listeners. This paper describes the development of the original 200-word SPRINT test, along with a description of the procedure used to reduce the 200-word test to 100 words and the results of a validation study conducted to evaluate how well the shortened 100-word test is able to capture the results from the full 200-word version of the SPRINT.

Spectrotemporal modulation sensitivity as a predictor of speech intelligibility in noise for hearing-impaired listeners

The audiogram accounts for only a portion of the variance in speech-reception performance in noise for hearing-impaired listeners. The remaining variance is often attributed to a combination of suprathreshold auditory distortion and non-auditory factors such as cognitive processing. This talk describes a series of studies demonstrating that a suprathreshold measure of sensitivity to spectro-temporal modulation (STM) can account for individual differences in speech-reception scores that are not predicted by the audiogram. STM stimuli are spectrally rippled noises with spectral-peak frequencies that shift over time, akin to modulations in a speech signal. The results show that STM sensitivity correlates to speech-reception performance in noise; that the correlation is ascribed mainly to the low-frequency portion of the stimulus (<2 kHz); and that STM sensitivity can account for individual differences in speech-reception thresholds for hearing-impaired listeners properly fit with individualized frequency-dependent gain. Hearing loss has the largest impact on STM sensitivity for low temporal rates and low carrier frequencies, suggesting a reduced ability to use temporal fine-structure information to detect slow-moving spectral peaks. STM detection is a fast, simple test of suprathreshold auditory function that complements the high-frequency audiogram to account for a substantial proportion of individual variability in speech reception in noise.

Selecting Appropriate Tests to Assess the Benefits of Bilateral Amplification With Hearing Aids.

The aim of this study was to investigate the effect of bilateral hearing aids (HA) in subjects with mild and moderate-to-severe hearing loss. This study was designed as a within-subject feasibility study. Bilateral HA use was assessed using different laboratory tests on speech reception, listening effort, noise tolerance, and localization. All data were evaluated with bilateral and unilateral HA fittings. Forty experienced bilateral HA users were included with hearing impairment ranging from mild to moderate-to-severe. Subjects were stratified into two groups based on the degree of hearing loss. Speech reception in noise, listening effort, and localization tests showed a bilateral benefit for the moderate-to-severely hearing-impaired subjects. A bilateral benefit was also observed for listening effort in the mildly hearing-impaired group. The assessment of listening effort shows promise as a measure of bilateral HA benefit for mild hearing impairment. Localization and speech reception in noise tests provide additional value for larger losses. The next step is to compare experienced unilateral with bilateral HA users.

The Galker test of speech reception in noise; associations with background variables, middle ear status, hearing, and language in Danish preschool children

PurposeWe tested “the Galker test”, a speech reception in noise test developed for primary care for Danish preschool children, to explore if the children's ability to hear and understand speech was associated with gender, age, middle ear status, and the level of background noise. MethodsThe Galker test is a 35-item audio-visual, computerized word discrimination test in background noise. Included were 370 normally developed children attending day care center. The children were examined with the Galker test, tympanometry, audiometry, and the Reynell test of verbal comprehension. Parents and daycare teachers completed questionnaires on the children's ability to hear and understand speech. As most of the variables were not assessed using interval scales, non-parametric statistics (Goodman–Kruskal's gamma) were used for analyzing associations with the Galker test score. For comparisons, analysis of variance (ANOVA) was used. Interrelations were adjusted for using a non-parametric graphic model. ResultsIn unadjusted analyses, the Galker test was associated with gender, age group, language development (Reynell revised scale), audiometry, and tympanometry. The Galker score was also associated with the parents’ and day care teachers’ reports on the children's vocabulary, sentence construction, and pronunciation. Type B tympanograms were associated with a mean hearing 5–6dB below that of than type A, C1, or C2. In the graphic analysis, Galker scores were closely and significantly related to Reynell test scores (Gamma (G)=0.35), the children's age group (G=0.33), and the day care teachers’ assessment of the children's vocabulary (G=0.26). ConclusionsThe Galker test of speech reception in noise appears promising as an easy and quick tool for evaluating preschool children's understanding of spoken words in noise, and it correlated well with the day care teachers’ reports and less with the parents’ reports.

A speech reception in noise test for preschool children (the Galker-test): Validity, reliability and acceptance

PurposeThis study evaluates initial validity and reliability of the “Galker test of speech reception in noise” developed for Danish preschool children suspected to have problems with hearing or understanding speech against strict psychometric standards and assesses acceptance by the children. MethodsThe Galker test is an audio-visual, computerised, word discrimination test in background noise, originally comprised of 50 word pairs. Three hundred and eighty eight children attending ordinary day care centres and aged 3–5 years were included. With multiple regression and the Rasch item response model it was examined whether the total score of the Galker test validly reflected item responses across subgroups defined by sex, age, bilingualism, tympanometry, audiometry and verbal comprehension. ResultsA total of 370 children (95%) accepted testing and 339 (87%) completed all 50 items. The analysis showed that 35 items fitted the Rasch model. Reliability was 0.75 before and after exclusion of the 15 non-fitting items. In the stepwise linear regression model age group of children could explain 20% of the variation in Galker-35-score, sex 1%, second language at home 4%, tympanometry in best ear 2%, and parental education another 2%. Other variable did not reach significance. ConclusionThe Galker-35 was well accepted by children down to the age of 3 years and results indicate that the scale represents construct valid and reliable measurement.

Audiometric Characteristics of a Dutch Family with a New Mutation in GATA3 Causing HDR Syndrome

We present the case of a Dutch family with a new mutation (c523_528dup) in GATA3 causing HDR syndrome. HDR syndrome is characterised by hypoparathyroidism, deafness and renal defects. In this study, we describe the audiometric characteristics of 5 patients from this family. Their hearing impairment was congenital, bilateral and symmetric. Audiograms showed mild-to-moderate hearing impairment with a flat audiogram configuration. Higher frequencies tended to be affected more strongly. Cross-sectional analyses showed no progression, and a mean audiogram was established. Psychophysical measurements in 3 HDR patients - including speech reception in noise, loudness scaling, gap detection and difference limen for frequency - were obtained to assess hearing function in greater detail. Overall, the results of the psychophysical measurements indicated characteristics of outer hair cell loss. CT scanning showed no anomalies in 3 of the HDR patients. Although 2 patients displayed vestibular symptoms, no anomalies in the vestibular system were found by vestibulo-ocular examination. Our results are in agreement with the theory that outer hair cell malfunctioning can play a major role in HDR syndrome.

Adaptation of Scoring Methods for Testing Cochlear Implant Users Using the Cantonese Hearing In Noise Test (CHINT)

It is often difficult to use an adaptive approach to evaluate speech reception in noise in cochlear implant (CI) users, because of variations in performance. Thus, two studies were conducted to develop an alternative method for scoring the Cantonese Hearing In Noise Test (CHINT) and to use this method for evaluating speech reception in CI users. In Study 1, 20 normal-hearing adults were tested using four scoring methods, including three modified and the standard HINT scoring method. The speech was presented in the front, and noise originated from the front, the right, or the left loudspeakers, as a standard HINT protocol. Threshold signal-to-noise ratio (S/N) and word intelligibility percent score (word score) were measured in each CHINT noise condition using each rule. In Study 2, depending on the word score of the individual CI user in the quiet CHINT condition, different adaptive rules were selected to score the responses from 12 CI users in the three noise conditions. The percentage of CI users who could successfully be tested using these scoring methods was evaluated. In Study 1, threshold S/Ns obtained using different rules were significantly different and consistent with expectations. The slopes of the performance-intensity function relating mean word scores and threshold S/Ns were linear and agreed well with previous findings. These results showed that the modified rules could be used to adaptively measure CHINT thresholds in noise. In Study 2, these modified rules were successful in measuring CHINT thresholds in 10 of the 12 participants, whose word scores in quiet exceeded 40%. These modified rules could be used in CI users whose speech reception ability could not have been measured otherwise.

Tinnitus in a Single-Sided Deaf Ear Reduces Speech Reception in the Nontinnitus Ear

The influence of tinnitus on speech reception is under debate. A few previous studies addressed this issue and compared speech reception in groups with and without tinnitus, with tinnitus arising in both ears or in the same test ear. Recently, we demonstrated that loudness of tinnitus in single-sided deafness (SSD) could be reduced dramatically by implanting and activating a cochlear implant (CI). The aim of the study was to evaluate whether changing the level of tinnitus in the SSD ear by disenabling or enabling the CI changes the speech reception in noise in the non-tinnitus ear. Fifteen CI users (MED-EL multichannel) with SSD and incapacitating tinnitus participated. They had an initial score of 6 or greater out of 10 on the Visual Analogue Scale (VAS) and an average total score of 58.05 (standard deviation [SD], 13.68) on the Tinnitus Questionnaire. The outcome measure, speech reception threshold (SRT) in noise using an adaptive procedure was measured in the nontinnitus ear using insert earphones. The measurements were performed with a high tinnitus level and a low tinnitus level in the SSD ear, realized by switching the CI off or on. Tinnitus loudness was assessed on a VAS, and tinnitus loudness was also matched using an audiometer. Speech reception in noise is significantly worse in case of high tinnitus loudness. The mean difference in SRT in the nontinnitus ear between the 2 conditions (SRTCI off-SRTCI on) of the 15 subjects was 1.98 dB SNR (SD, 3.01 dB SNR). The mean tinnitus loudness on the VAS was 7.2 (SD, 2.6) in the CI-off condition. In the CI-on condition, the mean VAS score significantly declined to 3.4 (SD, 2.5). Also, the tinnitus loudness match improved from 22 dB SL (SD, 14.4 dB SL) to 10 dB SL (SD, 10.1 dB SL) in the CI-on condition. Unilateral tinnitus can significantly decrease speech reception in noise in the nontinnitus ear.