Abstract:

The speech transmission index (STI) can be used to describe acoustical quality in classrooms. The objective of the work reported here was to establish the relationship between STI and user subjective perception of the listening environment by studying thirty university classrooms. STI measurements were made in these rooms when unoccupied. A questionnaire was developed to create a summary measure of perceived listening quality (PLQ) and to enquire about user-related factors that could affect PLQ. The questionnaire was administered to over 5700 students in 107 classes in the 30 rooms. Preliminary results suggest that the main factors contributing to increased PLQ are the perceived instructor speech level, the perceived quality of the classroom air and lighting, the proportion of time that the instructor speaks toward the audience, and the ``unoccupied'' STI. Use of a speech-reinforcement system reduced PLQ. [See NOISE-CON Proceedings for full paper.]