Effect of background noise on perception of English speech for Japanese listeners

To avoid the accidents induced by confusions of non-native speech perception in the presence of noise at work, this study examined the effect of background noise on the discrimination of English speech for Japanese listeners.

Normal hearing Japanese subjects, who have English learning experience to the level of college graduates, were tested with the CID W-22 word list in quiet settings and in the presence of white, low-frequency weighted (pink noise), or aircraft noise.

The discrimination scores were reduced as S/N ratio decreased, and more adversely affected by background white noise than pink or aircraft noise. The individual variability of English word discrimination scores for Japanese listeners was much larger as the S/N ratio decreased. The typical confusions among phoneme were /m/, /n/, and /s/.

The results of this study suggested that ineffective use of speech cues and difference in composition of English phonemes from Japanese could be responsible for degraded speech discrimination of non-native speech in noise. Moreover, it was expected that Japanese workers with age related hearing loss at higher frequencies might have great difficulty in perceiving English speech sounds in the presence of noise.