Cognitive load distorts the perception of core acoustic dimensions of speech

Abstract

Dual-tasking negatively impacts on speech perception by raising cognitive load. Previous research has shown that cognitive load increases reliance on lexical knowledge and decreases reliance on phonetic detail. Less is known about the effect of cognitive load on the perception of acoustic dimensions below the phonetic level. This study tested the effect of cognitive load on the ability to discriminate differences in duration, intensity, and fundamental frequency of a synthesized vowel. A psychophysical adaptive procedure was used to obtain just noticeable differences (JNDs) on each dimension under load and no load. Load was imposed via N-back tasks at two levels of difficulty (1-back, 2-back) and under two types of load (images, written nonwords). Compared to a control condition with no cognitive load, all N-back conditions increased JNDs across the three dimensions. JNDs were also higher under 2-back than 1-back load. Nonword load was marginally more detrimental than image load for intensity and fundamental frequency discrimination. Overall, the decreased auditory acuity demonstrates that the effect of cognitive load on the listening experience can be traced to distortions in the perception of core auditory dimensions.Dual-tasking negatively impacts on speech perception by raising cognitive load. Previous research has shown that cognitive load increases reliance on lexical knowledge and decreases reliance on phonetic detail. Less is known about the effect of cognitive load on the perception of acoustic dimensions below the phonetic level. This study tested the effect of cognitive load on the ability to discriminate differences in duration, intensity, and fundamental frequency of a synthesized vowel. A psychophysical adaptive procedure was used to obtain just noticeable differences (JNDs) on each dimension under load and no load. Load was imposed via N-back tasks at two levels of difficulty (1-back, 2-back) and under two types of load (images, written nonwords). Compared to a control condition with no cognitive load, all N-back conditions increased JNDs across the three dimensions. JNDs were also higher under 2-back than 1-back load. Nonword load was marginally more detrimental than image load for intensity and fundamen...