Evaluation of speech intelligibility on subway platforms from horizontally positioned line-array loudspeakers

摘要

The goal of any public address system should be to provide the listener with highly intelligible information; unfortunately that is not the case on many subway platforms and in other large public indoor spaces. High background noise levels combined with excessive reverberation and poor PA-system design result in low speech intelligibility and listener dissatisfaction. Stockholm Public Transport (SL) is in the process of upgrading the existing PA-systems on the underground platforms of Stockholm's subway system. The proposed PA-design consists of four horizontally placed line-array type loudspeakers per 180 m long platform. The design of the new PA-system has been evaluated through calculations of speech intelligibility metrics in room acoustic modeling software (ODEON, CATT-A) and STIPa measurements on several subway platforms. This paper presents the results of the evaluation; calculation and measurement results are compared and discussed. The proposed system design proved to be quite successful in terms of achieved speech intelligibility and system design efficiency.