The Perception of Speech Under Adverse Conditions

Talker intelligibility and perceptual adaptation under cochlear implant ͑CI͒-simulation and speech in multi-talker babble were compared. The stimuli consisted of 100 sentences produced by 20 native English talkers. The sentences were processed to simulate listening with an eight-channel CI or were mixed with multi-talker babble. Stimuli were presented to 400 listeners in a sentence transcription task ͑200 listeners in each condition͒. Perceptual adaptation was measured for each talker by comparing intelligibility in the first 20 sentences of the experiment to intelligibility in the last 20 sentences. Perceptual adaptation patterns were also compared across the two degradation conditions by comparing performance in blocks of ten sentences. The most intelligible talkers under CI-simulation also tended to be the most intelligible talkers in multi-talker babble. Furthermore, listeners demonstrated a greater degree of perceptual adaptation in the CI-simulation condition compared to the multi-talker babble condition although the extent of adaptation varied widely across talkers. Listeners reached asymptote later in the experiment in the CI-simulation condition compared with the multi-talker babble condition. Overall, these two forms of degradation did not differ in their effect on talker intelligibility, although they did result in differences in the amount and time-course of perceptual adaptation.

Section: A Speech Intelligibilitymentioning

confidence: 99%

Perceptual adaptation and intelligibility of multiple talkers for two types of degraded speech

Bent

Buchwald

Pisoni

2009

“…In Kiefte and Kluender (2008) and Alexander and Kluender (2010), acoustic energy at the vowel's F 2 was made reliable in the precursor sound by amplifying this frequency region by 20 dB or more. Assmann and Summerfield (2004) suggested that perceptual compensation reported by Darwin et al (1989) may occur only under extreme conditions, since it was only present for 30-dB changes in spectral slope. Perceptual sensitivity to more modest but still reliable signal properties is unknown.…”

Section: Introductionmentioning

confidence: 98%

Modest, reliable spectral peaks in preceding sounds influence vowel perception

Stilp

Anderson

2014

When a spectral property is reliable across an acoustic context and subsequent vowel target, perception deemphasizes this cue and shifts toward less predictable, more informative cues. This phenomenon (auditory perceptual calibration) has been demonstrated for reliable spectral peaks +20 dB or larger, but psychoacoustic findings predict sensitivity to more modest spectral peaks. Listeners identified vowel targets following a sentence with a reliable +2 to +15 dB spectral peak centered at F2 of the vowel. Vowel identifications weighted F2 significantly less when reliable peaks were at least +5 dB. Results demonstrate high sensitivity to reliable acoustic properties in the sensory environment.

“…A distant microphone collects, in addition to direct sound, the early and late reflections arriving after the direct sound. The early and late reflections fill the gaps in the temporal envelope of speech and reduce envelope modulation depth (Assmann and Summerfield, 2004). Although speech intelligibility is not affected much by reverberation for normal hearing (NH) listeners, it is degraded significantly for hearing impaired, cochlear implant (CI) users, and elderly people (Nabelek and Letowski, 1988;Kokkinakis et al, 2011;Nabelek and Letowski, 1985).…”

Section: Introductionmentioning

confidence: 99%

Blind binary masking for reverberation suppression in cochlear implants

Hazrati

Lee

Loizou

2013

A monaural binary time-frequency (T-F) masking technique is proposed for suppressing reverberation. The mask is estimated for each T-F unit by extracting a variance-based feature from the reverberant signal and comparing it against an adaptive threshold. Performance of the estimated binary mask is evaluated in three moderate to relatively high reverberant conditions (T 60 ¼ 0.3, 0.6, and 0.8 s) using intelligibility listening tests with cochlear implant users. Results indicate that the proposed T-F masking technique yields significant improvements in intelligibility of reverberant speech even in relatively high reverberant conditions (T 60 ¼ 0.8 s). The improvement is hypothesized to result from the recovery of the vowel/consonant boundaries, which are severely smeared in reverberation.