Level variations in speech: Effect on masking release in hearing-impaired listeners
Charlotte M Reed1, Joseph G Desloge1, Louis D Braida1
1Research Laboratory of Electronics, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA.
The Journal of the Acoustical Society of America
|August 1, 2016
Summary
Reducing amplitude variations in speech signals can significantly improve speech understanding for individuals with hearing impairments, especially in noisy environments. This processing enhances masking release and consonant identification.
Area of Science:
- Auditory Neuroscience
- Speech Processing
- Hearing Impairment Research
Background:
- Acoustic speech features time-varying amplitude envelopes, which can impede speech comprehension for hearing-impaired individuals.
- Previous research suggests temporal fine-structure (TFS) processing may improve speech reception in noise.
- Minimizing amplitude variations could be a key factor in enhancing speech intelligibility.
Purpose of the Study:
- To investigate the impact of reduced amplitude variations on speech masking release in hearing-impaired listeners.
- To compare the effectiveness of different speech processing techniques (peak clipping, TFS processing) with minimal level variations.
- To determine if decreased stimulus level variations improve consonant identification in noise.
Main Methods:
- Measured consonant identification for hearing-impaired listeners in continuous and fluctuating speech-shaped noise.
- Utilized speech processed to minimize amplitude variations, including peak clipping and TFS processing of envelope signals.
- Quantified normalized masking release for different speech processing conditions.
Main Results:
- Speech processed to have minimal level variations yielded substantially greater normalized masking release compared to speech with normal variations.
- Consonant identification performance was positively correlated with the reduction in stimulus level variations.
- The findings align with previous observations on the benefits of TFS processing.
Conclusions:
- Signal processing techniques that reduce stimulus level variations can significantly improve speech perception for hearing-impaired listeners in fluctuating noise.
- Minimizing amplitude envelope fluctuations is a promising strategy for enhancing speech intelligibility in challenging listening conditions.
- Further research into amplitude normalization techniques could lead to improved assistive listening devices.
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