ANOTHER LOOK AT THE RELATIONSHIPS BETWEEN FREQUENCY RESPONSE AND THE SPEECH TRANSMISSION INDEX, WITH RESPECT TO WORD SCORES AND ROAD TUNNELS

摘要

This paper takes another look at the relationships between frequency response and the speech transmission index (STI). Experience gained by the author and colleagues over many years of designing and commissioning sound systems has shown that a degraded frequency response can greatly reduce speech intelligibility. In reverberant, low noise environments, major degradation in responses can make speech essentially not understandable, and this loss of intelligibility is often barely reflected in the STI performance. Additionally, relatively small changes over an octave bandwidth, sometimes as small as 1 dB, can noticeably improve the perceived intelligibility of conversational speech and this change in perceived intelligibility is virtually not reflected in the STI.