Effects of speaker s and listener s acoustic environments on speech intelligibility and annoyance
Speech signal modification to increase intelligibility in noisy environments may cause discomfort in quieter environments. Human speech production in noise is known to improve intelligibility in noise. The socalled Lombard effect might cause annoyance in quiet environments. However, the effect disappears in quiet environments. This suggests that humans might modify their voices depending on the acoustic environment considering intelligibility and discomfort. The speech modification algorithms which use rules obtained from human speech production are expected to meet the demand for both of high intelligibility and reducing discomfort in various acoustic environments. This paper examined the influence of the coincidence between speaker's and listener's acoustic environments on speech intelligibility and the level of annoyance and to confirm the expectation. Speech produced by four Japanese speakers in quiet and noisy environments (at non, 66, 78, 90 dB) were presented to Japanese listeners in quiet and noisy environments (at non, 66, 78 90 dB) to measure intelligibility of words and the level of annoyance. The results showed that speech is less intelligible or more annoying when the listener's environment is different from the speaker's one. This supports that mimicking human speech production would meet the demand for high intelligibility and less annoyance.