Effects of Expanding Envelope Fluctuations on Consonant Perception in Hearing-Impaired Listeners

Abstract

This study examined the perceptual consequences of three speech enhancement schemes based on multiband nonlinear expansion of temporal envelope fluctuations between 10 and 20 Hz: (a) “idealized” envelope expansion of the speech before the addition of stationary background noise, (b) envelope expansion of the noisy speech, and (c) envelope expansion of only those time-frequency segments of the noisy speech that exhibited signal-to-noise ratios (SNRs) above −10 dB. Linear processing was considered as a reference condition. The performance was evaluated by measuring consonant recognition and consonant confusions in normal-hearing and hearing-impaired listeners using consonant-vowel nonsense syllables presented in background noise. Envelope expansion of the noisy speech showed no significant effect on the overall consonant recognition performance relative to linear processing. In contrast, SNR-based envelope expansion of the noisy speech improved the overall consonant recognition performance equivalent to a 1- to 2-dB improvement in SNR, mainly by improving the recognition of some of the stop consonants. The effect of the SNR-based envelope expansion was similar to the effect of envelope-expanding the clean speech before the addition of noise.

Improved tactile speech perception and noise robustness using audio-to-tactile sensory substitution with amplitude envelope expansion

“…Performance for consonant pairs differing by manner and place of articulation was improved in noise but not in quiet. This improved performance was anticipated, as envelope expansion improves the salience of fast onset amplitude envelope changes, which are crucial to these contrasts 22 . Like for voicing cues, these cues may have been sufficiently salient in quiet even without envelope expansion (as indicated by the high performance in this and previous work 12 , 14 ), but have been made more salient by envelope expansion in noise.…”

“…This enhancement would be expected to apply for both consonants and vowels for phonemes in noise. Envelope expansion was also expected to enhance onset cues and other fast amplitude envelope changes and thereby particularly aid performance in noise for consonants differing by both manner and place of articulation, which heavily rely on these cues 22 .…”

A robust speech enhancement method in noisy environments

“…The significance of the temporal envelope and its application in speech enhancement has been extensively explored in various studies [27][28][29]. The objective of this step is to verify and validate the hypothesis that "enhancing the temporal envelope of noisy speech can considerably enhance speech quality".…”