Speech degradation as measured by the Rapid Speech Transmission Index (RASTI)

This study demonstrates degradation of a modulated speech-like signal in a typical listening environment as measured by the new Bruel and Kjaer Rapid Speech Transmission Index (RASTI) System. Thirty-four adults were seated in a typical college classroom. Measurements of the RASTI signal were made at 17 different seating locations. Results showed that the speech-like signal was substantially degraded, even at the front-row center seat. Loss of critical speech information was greater at less favorable locations. These results suggest that because hearing aids cannot amplify nonexistent speech information, the effects of distance must be considered when fitting amplification systems.