An algorithm that improves speech intelligibility in noise for normal-hearing listeners.
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ABSTRACT:
SUBMITTER: Kim G
PROVIDER: S-EPMC2757424 | biostudies-other | 2009 Sep
REPOSITORIES: biostudies-other
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Project description:Reverberation can have a strong detrimental effect on speech intelligibility in noise. Two main monaural effects were studied here: the temporal smearing of the target speech, which makes the speech less understandable, and the temporal smearing of the noise, which reduces the opportunity for listening in the masker dips. These phenomena have been shown to affect normal-hearing (NH) listeners. The aim of this study was to understand whether hearing-impaired (HI) listeners are more affected by reverberation, and if so to identify which of these two effects is responsible. They were investigated separately and in combination, by applying reverberation either on the target speech, on the noise masker, or on both sources. Binaural effects were not investigated here. Intelligibility scores in the presence of stationary and modulated noise were systematically compared for both NH and HI listeners in these situations. At the optimal signal-to-noise ratios (SNRs) (that is to say, the SNRs with the least amount of floor and ceiling effects), the temporal smearing of both the speech and the noise had a similar effect for the HI and NH listeners, so that reverberation was not more detrimental for the HI listeners. There was only a very limited dip listening benefit at this SNR for either group. Some differences across group appeared at the SNR maximizing dip listening, but they could not be directly related to an effect of reverberation, and were rather due to floor effects or to the reduced ability of the HI listeners to benefit from dip listening, even in the absence of reverberation.
| S-EPMC9428532 | biostudies-literature
Project description:Purpose Age-related sensorineural hearing loss can dramatically affect speech recognition performance due to reduced audibility and suprathreshold distortion of spectrotemporal information. Normal aging produces changes within the central auditory system that impose further distortions. The goal of this study was to characterize the effects of aging and hearing loss on perceptual representations of speech. Method We asked whether speech intelligibility is supported by different patterns of spectrotemporal modulations (STMs) in older listeners compared to young normal-hearing listeners. We recruited 3 groups of participants: 20 older hearing-impaired (OHI) listeners, 19 age-matched normal-hearing listeners, and 10 young normal-hearing (YNH) listeners. Listeners performed a speech recognition task in which randomly selected regions of the speech STM spectrum were revealed from trial to trial. The overall amount of STM information was varied using an up-down staircase to hold performance at 50% correct. Ordinal regression was used to estimate weights showing which regions of the STM spectrum were associated with good performance (a "classification image" or CImg). Results The results indicated that (a) large-scale CImg patterns did not differ between the 3 groups; (b) weights in a small region of the CImg decreased systematically as hearing loss increased; (c) CImgs were also nonsystematically distorted in OHI listeners, and the magnitude of this distortion predicted speech recognition performance even after accounting for audibility; and (d) YNH listeners performed better overall than the older groups. Conclusion We conclude that OHI/older normal-hearing listeners rely on the same speech STMs as YNH listeners but encode this information less efficiently. Supplemental Material https://doi.org/10.23641/asha.7859981.
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Project description:Cubick and Dau [(2016). Acta Acust. Acust. 102, 547-557] showed that speech reception thresholds (SRTs) in noise, obtained with normal-hearing listeners, were significantly higher with hearing aids (HAs) than without. Some listeners reported a change in their spatial perception of the stimuli due to the HA processing, with auditory images often being broader and closer to the head or even internalized. The current study investigated whether worse speech intelligibility with HAs might be explained by distorted spatial perception and the resulting reduced ability to spatially segregate the target speech from the interferers. SRTs were measured in normal-hearing listeners with or without HAs in the presence of three interfering talkers or speech-shaped noises. Furthermore, listeners were asked to sketch their spatial perception of the acoustic scene. Consistent with the previous study, SRTs increased with HAs. Spatial release from masking was lower with HAs than without. The effects were similar for noise and speech maskers and appeared to be accounted for by changes to energetic masking. This interpretation was supported by results from a binaural speech intelligibility model. Even though the sketches indicated a change of spatial perception with HAs, no direct link between spatial perception and segregation of talkers could be shown.
| S-EPMC6246072 | biostudies-other
Project description:Despite considerable effort, monaural (single-microphone) algorithms capable of increasing the intelligibility of speech in noise have remained elusive. Successful development of such an algorithm is especially important for hearing-impaired (HI) listeners, given their particular difficulty in noisy backgrounds. In the current study, an algorithm based on binary masking was developed to separate speech from noise. Unlike the ideal binary mask, which requires prior knowledge of the premixed signals, the masks used to segregate speech from noise in the current study were estimated by training the algorithm on speech not used during testing. Sentences were mixed with speech-shaped noise and with babble at various signal-to-noise ratios (SNRs). Testing using normal-hearing and HI listeners indicated that intelligibility increased following processing in all conditions. These increases were larger for HI listeners, for the modulated background, and for the least-favorable SNRs. They were also often substantial, allowing several HI listeners to improve intelligibility from scores near zero to values above 70%.
| S-EPMC3799726 | biostudies-other
Project description:In recent years, a growing body of literature has explored the effect of hearing impairment on the neural processing of speech, particularly related to the neural tracking of speech envelopes. However, only limited work has focused on the potential usage of the method for evaluating the effect of hearing aids designed to amplify and process the auditory input provided to hearing-impaired listeners. The current study investigates how directional sound processing in hearing-aids, denoted directionality, affects the neural tracking and encoding of speech in EEG recorded from 11 older hearing-impaired listeners. Behaviorally, the task performance improved when directionality was applied, while subjective ratings of listening effort were not affected. The reconstruction of the to-be-attended speech envelopes improved significantly when applying directionality, as well as when removing the background noise altogether. When inspecting the modelled response of the neural encoding of speech, a faster transition was observed between the early bottom-up response and the later top-down attentional-driven responses when directionality was applied. In summary, hearing-aid directionality affects both the neural speech tracking and neural encoding of to-be-attended speech. This result shows that hearing-aid signal processing impacts the neural processing of sounds and that neural speech tracking is indicative of the benefits associated with applying hearing-aid processing algorithms.
| S-EPMC9228639 | biostudies-literature
Project description:The present investigation carried out acoustic analyses of vowels in clear and conversational speech produced by 41 talkers. Mixed-effects models were then deployed to examine relationships among acoustic and perceptual data for these vowels. Acoustic data include vowel duration, steady-state formant frequencies, and two measures of dynamic formant movement. Perceptual data consist of vowel intelligibility in noise for young normal-hearing and elderly hearing-impaired listeners, as reported by Ferguson in 2004 and 2012 [J. Acoust. Soc. Am. 116, 2365-2373 (2004); J. Speech Lang. Hear. Res. 55, 779-790 (2012)], respectively. Significant clear speech effects were observed for all acoustic metrics, although not all measures changed for all vowels and considerable talker variability was observed. Mixed-effects analyses revealed that the contribution of duration and steady-state formant information to vowel intelligibility differed for the two listener groups. This outcome is consistent with earlier research suggesting that hearing loss, and possibly aging, alters the way acoustic cues are used for identifying vowels.
| S-EPMC4048446 | biostudies-other
Project description:Speech understanding in noisy environments is still one of the major challenges for cochlear implant (CI) users in everyday life. We evaluated a speech enhancement algorithm based on neural networks (NNSE) for improving speech intelligibility in noise for CI users. The algorithm decomposes the noisy speech signal into time-frequency units, extracts a set of auditory-inspired features and feeds them to the neural network to produce an estimation of which frequency channels contain more perceptually important information (higher signal-to-noise ratio, SNR). This estimate is used to attenuate noise-dominated and retain speech-dominated CI channels for electrical stimulation, as in traditional n-of-m CI coding strategies. The proposed algorithm was evaluated by measuring the speech-in-noise performance of 14 CI users using three types of background noise. Two NNSE algorithms were compared: a speaker-dependent algorithm, that was trained on the target speaker used for testing, and a speaker-independent algorithm, that was trained on different speakers. Significant improvements in the intelligibility of speech in stationary and fluctuating noises were found relative to the unprocessed condition for the speaker-dependent algorithm in all noise types and for the speaker-independent algorithm in 2 out of 3 noise types. The NNSE algorithms used noise-specific neural networks that generalized to novel segments of the same noise type and worked over a range of SNRs. The proposed algorithm has the potential to improve the intelligibility of speech in noise for CI users while meeting the requirements of low computational complexity and processing delay for application in CI devices.
| S-EPMC5256482 | biostudies-literature
Project description:Speech perception in background noise is difficult for many individuals, and there is considerable performance variability across listeners. The combination of physiological and behavioral measures may help to understand sources of this variability for individuals and groups and prove useful clinically with hard-to-test populations. The purpose of this study was threefold: (1) determine the effect of signal-to-noise ratio (SNR) and signal level on cortical auditory evoked potentials (CAEPs) and sentence-level perception in older normal-hearing (ONH) and older hearing-impaired (OHI) individuals, (2) determine the effects of hearing impairment and age on CAEPs and perception, and (3) explore how well CAEPs correlate with and predict speech perception in noise.Two groups of older participants (15 ONH and 15 OHI) were tested using speech-in-noise stimuli to measure CAEPs and sentence-level perception of speech. The syllable /ba/, used to evoke CAEPs, and sentences were presented in speech-spectrum background noise at four signal levels (50, 60, 70, and 80 dB SPL) and up to seven SNRs (-10, -5, 0, 5, 15, 25, and 35 dB). These data were compared between groups to reveal the hearing impairment effect and then combined with previously published data for 15 young normal-hearing individuals to determine the aging effect.Robust effects of SNR were found for perception and CAEPs. Small but significant effects of signal level were found for perception, primarily at poor SNRs and high signal levels, and in some limited instances for CAEPs. Significant effects of age were seen for both CAEPs and perception, while hearing impairment effects were only found with perception measures. CAEPs correlate well with perception and can predict SNR50s to within 2 dB for ONH. However, prediction error is much larger for OHI and varies widely (from 6 to 12 dB) depending on the model that was used for prediction.When background noise is present, SNR dominates both perception-in-noise testing and cortical electrophysiological testing, with smaller and sometimes significant contributions from signal level. A mismatch between behavioral and electrophysiological results was found (hearing impairment effects were primarily only seen for behavioral data), illustrating the possible contributions of higher order cognitive processes on behavior. It is interesting that the hearing impairment effect size was more than five times larger than the aging effect size for CAEPs and perception. Sentence-level perception can be predicted well in normal-hearing individuals; however, additional research is needed to explore improved prediction methods for older individuals with hearing impairment.
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Project description:Sensory and motor skills can be improved with training, but learning is often restricted to practice stimuli. As an exception, training on closed-loop (CL) sensorimotor interfaces, such as action video games and musical instruments, can impart a broad spectrum of perceptual benefits. Here we ask whether computerized CL auditory training can enhance speech understanding in levels of background noise that approximate a crowded restaurant. Elderly hearing-impaired subjects trained for 8 weeks on a CL game that, like a musical instrument, challenged them to monitor subtle deviations between predicted and actual auditory feedback as they moved their fingertip through a virtual soundscape. We performed our study as a randomized, double-blind, placebo-controlled trial by training other subjects in an auditory working-memory (WM) task. Subjects in both groups improved at their respective auditory tasks and reported comparable expectations for improved speech processing, thereby controlling for placebo effects. Whereas speech intelligibility was unchanged after WM training, subjects in the CL training group could correctly identify 25% more words in spoken sentences or digit sequences presented in high levels of background noise. Numerically, CL audiomotor training provided more than three times the benefit of our subjects' hearing aids for speech processing in noisy listening conditions. Gains in speech intelligibility could be predicted from gameplay accuracy and baseline inhibitory control. However, benefits did not persist in the absence of continuing practice. These studies employ stringent clinical standards to demonstrate that perceptual learning on a computerized audio game can transfer to "real-world" communication challenges.
| S-EPMC5997394 | biostudies-literature
Project description:Purpose This study investigated methods used to simulate factors associated with reduced audibility, increased speech levels, and spectral shaping for aided older adults with hearing loss. Simulations provided to younger normal-hearing adults were used to investigate the effect of sensation level, speech presentation level, and spectral shape in comparison to older adults with hearing loss. Method Measures were assessed in quiet, steady-state noise, and speech-modulated noise. Older adults with hearing loss listened to speech that was spectrally shaped according to their hearing thresholds. Younger adults with normal hearing listened to speech that simulated the hearing-impaired group's (a) reduced audibility, (b) increased speech levels, and (c) spectral shaping. Group comparisons were made based on speech recognition performance and masking release. Additionally, younger adults completed measures of listening effort and perceived speech quality to assess if differences across simulations in these outcome measures were similar to those for speech recognition. Results Across the various simulations employed, testing in the presence of a threshold matching noise best matched differences in speech recognition and masking release between younger and older adults. This result remained consistent across the other two outcome measures. Conclusions A combination of audibility, speech level, and spectral shape factors is required to simulate differences between listeners with normal and impaired hearing in recognition, listening effort, and perceived speech quality. The use of spectrally shaped and amplified speech in the presence of threshold matching noise best provided this simulated control. Supplemental Material https://doi.org/10.23641/asha.13224632.
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