Time‐intensity envelope cues for consonant recognition

Abstract

A primary source of perceptual information for the cochlear implant user in the time‐intensity envelope of the speech waveform. The purpose of this study was to estimate the amount and type of information for consonant recognition potentially available in the time‐intensity envelope of speech. The experimental stimuli were generated from the time‐intensity envelopes of 19 /aCa/ utterances (C = /p, t, k, b, d, g, f, θ, s, ∫, v, ð, z, ȝ, m, n, r, l, j/), spoken by a male talker. The envelopes were obtained by full‐wave rectifying and low‐pass filtering the speech waveforms at 2000, 200, and 20 Hz. These envelopes were used to multiply noise with a 3‐kHz bandwidth, producing three sets of envelope stimuli with identical, flat spectra that differed in the amount of time‐varying in their amplitude envelopes. The unprocessed speech waveforms and the three sets of envelope stimuli were presented to 12 normal‐hearing subjects in blocked, closed‐set consonant recognition tests. Individual and group confusion matrices from each test were submitted to multidimensional scaling analyses (SINDSCAL) and information transmission analyses (SINFA). The results of these analyses revealed that three different envelope features account for most of the consonant information in the time‐intensity envelope of speech.