Appropriate background noise level regarding speech privacy and annoyance in a train cabin

Abstract

The background noise levels in passenger cars of high-speed trains were investigated in relation to speech privacy and noise annoyance. Auditory experiments were conducted for speech signals with background sounds varying speech to noise ratios (SNR). The results showed that speech privacy decreased considerably and noise annoyance increased as the SNR increased from -6 to -3 dBA. In addition, annoyance increased significantly for the increase of background noise level over 63 dBA. The optimal level of interior noise was suggested as 60-63 dBA for enhancement of acoustic comfort with normal speech level in high speed trains.