Related Experiment Videos
Effect of reducing temporal intensity modulations on sentence intelligibility
1Dept. of Otolaryngology, University Hospital VU, Amsterdam, The Netherlands.
The Journal of the Acoustical Society of America
|January 1, 1997
Summary
Reducing speech modulation significantly impacts intelligibility. Deterministic modulation reduction lowers speech reception threshold (SRT) more than stochastic reduction, indicating other factors beyond modulation loss affect understanding.
Area of Science:
- Acoustics
- Speech Perception
- Signal Processing
Background:
- Temporal intensity envelope modulations are crucial for speech intelligibility.
- Understanding how modulation reduction affects speech perception is key for auditory research.
- Previous studies suggest additive noise impacts intelligibility through mechanisms beyond simple modulation reduction.
Purpose of the Study:
- To investigate the effect of deterministic modulation reduction on speech intelligibility.
- To compare the impact of deterministic versus stochastic modulation reduction on the speech-reception threshold (SRT).
- To analyze the contribution of modulation reduction to the overall effect of additive noise on speech intelligibility.
Main Methods:
- Modulations in 24 1/4-octave bands were deterministically reduced by adjusting peaks and troughs.
- Speech-reception threshold (SRT) in noise was measured to assess intelligibility under varying degrees of modulation reduction.
- Performance was also scored by counting correctly received sentences in quiet for severe modulation reduction.
- Deterministic modulation reduction was compared against stochastic modulation reduction (achieved by adding noise).
Main Results:
- Intelligibility dropped to 50% at a modulation-transfer factor of 0.10 for deterministic modulation reduction.
- For modulation reduction by adding noise, 50% intelligibility was reached at a modulation-transfer factor of 0.27.
- These results indicate that additive noise has a greater detrimental effect on intelligibility than solely modulation reduction.
Conclusions:
- The impact of additive noise on speech intelligibility is not fully explained by modulation reduction alone.
- Factors such as the introduction of irrelevant modulations and corruption of the fine structure by noise also significantly affect intelligibility.
- Further research should consider these additional factors to fully understand noise's effect on speech perception.