Abstract:

The quality of speech transmission in an auditorium equipped with a public address system is determined by the characteristics of both the electro-acoustic system and the acoustics of the auditorium. Potentially, various types of distortions and interferences in the sound transmission from talker to listener may have a negative effect on speech intelligibility. Assessment of the intelligibility by means of subjective tests with speakers and listeners offers a representative quality measure of the total chain, without however providing diagnostic information on the underlying type of distortion. Objective methods, like the speech transmission index (STI) [H. J. M. Steeneken and T. Houtgast, J. Acoust. Soc. Am. 67, 318--326 (1980)] may not only predict overall speech intelligibility, but may also provide valuable diagnostic information. However, in order to properly represent the effect of all potential types of distortion in a single index, and to obtain relevant diagnostic information, the test signal and the measuring procedure should be chosen very careful. In this context the STI and other methods, like the use of impulse response measurements (MLSSA), will be discussed. Examples will be presented of results obtained in various environments (e.g., railway stations, highway tunnels, and aircraft cabins). [See NOISE-CON Proceedings for full paper.]