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Speech degradation as measured by the Rapid Speech Transmission Index (RASTI)
Ear and Hearing
|April 1, 1991
Summary
Speech signal quality significantly degrades in typical classrooms, even close to the source. This degradation impacts hearing aid effectiveness by reducing available speech information.
Area of Science:
- Acoustics
- Audiology
- Speech Science
Background:
- Understanding speech in noisy or reverberant environments is crucial for hearing aid users.
- The impact of room acoustics on speech intelligibility requires further investigation in realistic settings.
Purpose of the Study:
- To quantify speech signal degradation in a typical classroom environment.
- To assess the performance of the Bruel and Kjaer Rapid Speech Transmission Index (RASTI) System in measuring speech intelligibility.
Main Methods:
- A modulated speech-like signal was used to measure the Speech Transmission Index (STI).
- Measurements were conducted in a college classroom with 34 adult participants at 17 different seating locations.
- The Bruel and Kjaer Rapid Speech Transmission Index (RASTI) System was employed for signal assessment.
Main Results:
- Significant degradation of the speech-like signal was observed across all measured locations.
- Even at the front-row center seat, the speech signal was substantially degraded.
- Speech information loss increased notably at less favorable seating positions.
Conclusions:
- Classroom acoustics can severely impair speech signal quality, limiting the effectiveness of hearing aids.
- The distance from the sound source and room acoustics are critical factors in speech intelligibility.
- Fitting amplification systems for hearing aids must account for environmental acoustic conditions and signal degradation.