Individual variations in vocal and cognitive responses to simulated acoustic environments

Abstract

Humans “automatically” make vocal and speech adjustments in response to room acoustics; however, it is unclear whether these adjustments require additional cognitive load. Beyond this automatic adjustment, speakers may have to employ a speech production technique to enhance their intelligibility in situations such as public speaking. How does room acoustics challenge speakers on such occasions? Understanding the relationship between room acoustics, speech production, and cognitive load has practical implications for various areas, including speech training and room design. This study describes the associated change in cognitive load when speaking with and without a speech production technique at three levels of reverberation time (i.e., 0.05 s, 1.2 s, and 1.83 s at 125 Hz). Ten adult native speakers of American English were asked to read sentences in simulated acoustic environments using two types of speech production: habitual speech and clear speech, an intelligibility-enhancing technique. Cognitive load during the speech tasks was monitored with pupillometry and a subjective self-rating scale. Participants’ speech production behaviors were acoustically assessed via speech rate and alpha ratio. Preliminary results indicate that reverberation time significantly affects speech production behaviors and cognitive load and that the pattern of cognitive response varies substantially among the speakers.