Deep learning restores speech intelligibility in multi-talker interference for cochlear implant users.

Cochlear implants (CIs) do not offer the same level of effectiveness in noisy environments as in quiet settings. Current single-microphone noise reduction algorithms in hearing aids and CIs only remove predictable, stationary noise, and are ineffective against realistic, non-stationary noise such as multi-talker interference. Recent developments in deep neural network (DNN) algorithms have achieved noteworthy performance in speech enhancement and separation, especially in removing speech noise.

Optimized gain functions in ideal time-frequency masks and their application to dereverberation for cochlear implants.

The present study investigated three different reverberation suppression rules based on the parametric ideal ratio mask, which is a generalization of the classical Wiener filter with additional parameters controlling the threshold and slope. Automatic selection of parameter values for the ideal ratio mask was performed using particle swarm optimization. Three different parameter sets were tested using sentences corrupted by reverberation.

Listening benefits in speech-in-speech recognition are altered under reverberant conditions.

In speech-in-speech recognition, listeners' performance improves when spatial and linguistic properties of background and target speech differ. However, it is unclear if these benefits interact or whether they persist under reverberant conditions typical of indoor listening. To address these issues, these benefits were tested together in the presence and absence of reverberation.

Listeners Experience Linguistic Masking Release in Noise-Vocoded Speech-in-Speech Recognition.

Purpose: The purpose of this study was to evaluate whether listeners with normal hearing perceiving noise-vocoded speech-in-speech demonstrate better intelligibility of target speech when the background speech was mismatched in language (linguistic release from masking [LRM]) and/or location (spatial release from masking [SRM]) relative to the target. We also assessed whether the spectral resolution of the noise-vocoded stimuli affected the presence of LRM and SRM under these conditions.

Method: In Experiment 1, a mixed factorial design was used to simultaneously manipulate the masker language (within-subject, English vs.

Binaural Speech Understanding With Bilateral Cochlear Implants in Reverberation.

Purpose: The purpose of this study was to investigate whether bilateral cochlear implant (CI) listeners who are fitted with clinical processors are able to benefit from binaural advantages under reverberant conditions. Another aim of this contribution was to determine whether the magnitude of each binaural advantage observed inside a highly reverberant environment differs significantly from the magnitude measured in a near-anechoic environment.

Method: Ten adults with postlingual deafness who are bilateral CI users fitted with either Nucleus 5 or Nucleus 6 clinical sound processors (Cochlear Corporation) participated in this study.

Spatially separating language masker from target results in spatial and linguistic masking release.

Several studies demonstrate that in complex auditory scenes, speech recognition is improved when the competing background and target speech differ linguistically. However, such studies typically utilize spatially co-located speech sources which may not fully capture typical listening conditions. Furthermore, co-located presentation may overestimate the observed benefit of linguistic dissimilarity.

Evaluation of a spectral subtraction strategy to suppress reverberant energy in cochlear implant devices.

The smearing effects of room reverberation can significantly impair the ability of cochlear implant (CI) listeners to understand speech. To ameliorate the effects of reverberation, current dereverberation algorithms focus on recovering the direct sound from the reverberated signal by inverse filtering the reverberation process. This contribution describes and evaluates a spectral subtraction (SS) strategy capable of suppressing late reflections.

Reducing the impact of wind noise on cochlear implant processors with two microphones.

Behind-the-ear (BTE) processors of cochlear implant (CI) devices offer little to almost no protection from wind noise in most incidence angles. To assess speech intelligibility, eight CI recipients were tested in 3 and 9 m/s wind. Results indicated that speech intelligibility decreased substantially when the wind velocity, and in turn the wind sound pressure level, increased.

Classification of fricative consonants for speech enhancement in hearing devices.

Objective: To investigate a set of acoustic features and classification methods for the classification of three groups of fricative consonants differing in place of articulation.

Method: A support vector machine (SVM) algorithm was used to classify the fricatives extracted from the TIMIT database in quiet and also in speech babble noise at various signal-to-noise ratios (SNRs). Spectral features including four spectral moments, peak, slope, Mel-frequency cepstral coefficients (MFCC), Gammatone filters outputs, and magnitudes of fast Fourier Transform (FFT) spectrum were used for the classification.

Perception of consonants in reverberation and noise by adults fitted with bimodal devices.

Purpose: The purpose of this study was to evaluate the contribution of a contralateral hearing aid to the perception of consonants, in terms of voicing, manner, and place-of-articulation cues in reverberation and noise by adult cochlear implantees aided by bimodal fittings.

Method: Eight postlingually deafened adult cochlear implant (CI) listeners with a fully inserted CI in 1 ear and low-frequency hearing in the other ear were tested on consonant perception. They were presented with consonant stimuli processed in the following experimental conditions: 1 quiet condition, 2 different reverberation times (0.

Binaural advantages in users of bimodal and bilateral cochlear implant devices.

This paper investigates to what extent users of bilateral and bimodal fittings should expect to benefit from all three different binaural advantages found to be present in normal-hearing listeners. Head-shadow and binaural squelch are advantages occurring under spatially separated speech and noise, while summation emerges when speech and noise coincide in space. For 14 bilateral or bimodal listeners, speech reception thresholds in the presence of four-talker babble were measured in sound-field under various speech and noise configurations.

Effects of early and late reflections on intelligibility of reverberated speech by cochlear implant listeners.

The purpose of this study was to determine the overall impact of early and late reflections on the intelligibility of reverberated speech by cochlear implant listeners. Two specific reverberation times were assessed. For each reverberation time, sentences were presented in three different conditions wherein the target signal was filtered through the early, late or entire part of the acoustic impulse response.

Single and multiple microphone noise reduction strategies in cochlear implants.

To restore hearing sensation, cochlear implants deliver electrical pulses to the auditory nerve by relying on sophisticated signal processing algorithms that convert acoustic inputs to electrical stimuli. Although individuals fitted with cochlear implants perform well in quiet, in the presence of background noise, the speech intelligibility of cochlear implant listeners is more susceptible to background noise than that of normal hearing listeners. Traditionally, to increase performance in noise, single-microphone noise reduction strategies have been used.

The impact of reverberant self-masking and overlap-masking effects on speech intelligibility by cochlear implant listeners (L).

The purpose of this study is to determine the relative impact of reverberant self-masking and overlap-masking effects on speech intelligibility by cochlear implant listeners. Sentences were presented in two conditions wherein reverberant consonant segments were replaced with clean consonants, and in another condition wherein reverberant vowel segments were replaced with clean vowels. The underlying assumption is that self-masking effects would dominate in the first condition, whereas overlap-masking effects would dominate in the second condition.

A channel-selection criterion for suppressing reverberation in cochlear implants.

Little is known about the extent to which reverberation affects speech intelligibility by cochlear implant (CI) listeners. Experiment 1 assessed CI users' performance using Institute of Electrical and Electronics Engineers (IEEE) sentences corrupted with varying degrees of reverberation. Reverberation times of 0.

Multi-microphone adaptive noise reduction strategies for coordinated stimulation in bilateral cochlear implant devices.

Bilateral cochlear implant (BI-CI) recipients achieve high word recognition scores in quiet listening conditions. Still, there is a substantial drop in speech recognition performance when there is reverberation and more than one interferers. BI-CI users utilize information from just two directional microphones placed on opposite sides of the head in a so-called independent stimulation mode.

Selective-tap blind signal processing for speech separation.

In this paper, we propose a new blind multichannel adaptive filtering scheme, which incorporates a partial-updating mechanism in the error gradient of the update equation. The proposed blind processing algorithm operates in the time-domain by updating only a selected portion of the adaptive filters. The algorithm steers all computational resources to filter taps having the largest magnitude gradient components on the error surface.

Selective-Tap Blind Dereverberation for Two-Microphone Enhancement of Reverberant Speech.

In this letter we propose a novel approach for two-microphone enhancement of speech corrupted by reverberation. Our approach steers computational resources to filter coefficients having the largest impact on the error surface and therefore only updates a subset of coefficients in every iteration. Experimental results carried out in a realistically reverberant setup indicate that the performance of the proposed algorithm is comparable to the performance of its full-update counterpart.

Using blind source separation techniques to improve speech recognition in bilateral cochlear implant patients.

Bilateral cochlear implants seek to restore the advantages of binaural hearing by improving access to binaural cues. Bilateral implant users are currently fitted with two processors, one in each ear, operating independent of one another. In this work, a different approach to bilateral processing is explored based on blind source separation (BSS) by utilizing two implants driven by a single processor.