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Effect of temporal envelope smearing on speech reception
R Drullman1, J M Festen, R Plomp
1Department of Oto-rhino-laryngology, Free University Hospital, Amsterdam, The Netherlands.
The Journal of the Acoustical Society of America
|February 1, 1994
Summary
Smearing the temporal envelope severely impacts speech intelligibility, especially with narrow frequency bands and low cutoff frequencies. Modulation frequencies above 16 Hz offer limited benefit for sentence recognition.
Area of Science:
- Auditory Perception
- Speech Processing
- Psychoacoustics
Background:
- Temporal envelope processing is crucial for speech understanding.
- The impact of temporal envelope smearing on speech reception threshold (SRT) and phoneme identification is not fully understood.
Purpose of the Study:
- To investigate the effect of smearing the temporal envelope on SRT for sentences in noise.
- To examine the impact of temporal envelope smearing on phoneme identification in normal-hearing listeners.
Main Methods:
- Speech was divided into frequency bands (1/4, 1/2, or 1 oct).
- Amplitude envelopes were low-pass filtered at various cutoff frequencies (0-64 Hz).
- Sentence intelligibility and phoneme identification (vowels, consonants) were assessed.
Main Results:
- Narrow bands and low cutoff frequencies (0-2 Hz) severely reduced sentence intelligibility.
- Modulation frequencies above 16 Hz had minimal impact on intelligibility.
- Consonant identification was more affected than vowel identification, with specific confusions noted for vowels and stop consonants.
Conclusions:
- Temporal envelope smearing significantly degrades speech perception, particularly at low modulation frequencies and narrow bandwidths.
- Consonants, especially stop consonants, are more vulnerable to temporal envelope distortions than vowels.
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