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Recognition of time-distorted sentences by normal-hearing and cochlear-implant listeners
1Department of Auditory Implants and Perception, House Ear Institute, Los Angeles, California 90057, USA. qfu@hei.org
The Journal of the Acoustical Society of America
|February 24, 2001
Summary
Time-compressed speech recognition is challenging for cochlear implant (CI) users due to limited spectral resolution. Some CI users struggle with rapid speech, impacting their auditory temporal processing abilities.
Area of Science:
- Auditory Neuroscience
- Speech Processing
- Hearing Technology
Background:
- Sentence recognition is crucial for effective communication.
- Time compression alters speech duration, posing challenges for auditory perception.
- Cochlear implants (CI) aim to restore hearing but have limitations in processing complex auditory signals.
Purpose of the Study:
- To evaluate the impact of time compression and expansion on sentence recognition in normal-hearing (NH) listeners and cochlear-implant (CI) recipients.
- To investigate the role of spectral resolution in processing time-altered speech.
- To identify factors contributing to difficulties in speech recognition for CI users.
Main Methods:
- Sentence recognition tests were administered to five CI users (Nucleus-22, 4-channel CIS processors) and five NH listeners (4-channel or 32-channel noise-band processors).
- Speech stimuli were subjected to time compression and expansion.
- Temporal gap detection tasks were used to assess auditory temporal processing in CI users.
Main Results:
- NH listeners showed minimal impact from time expansion but varied recognition of time-compressed speech based on spectral resolution.
- Fine spectral resolution (32 channels) allowed NH listeners to recognize time-compressed speech effectively, even at 40 ms/phoneme.
- Coarse spectral resolution (4 channels) required longer durations (60 ms/phoneme) for similar recognition in NH listeners.
- CI user performance was variable; poorer performers struggled with time-compressed speech and temporal gap detection.
Conclusions:
- Limited spectral resolution significantly impairs the ability to recognize time-compressed speech.
- Some CI users experience greater difficulty with rapid speech due to reduced spectral resolution and temporal processing deficits.
- These findings highlight the need for improved spectral and temporal processing in CI technology to enhance speech understanding in challenging listening conditions.