Discrimination Thresholds of Duration, Intensity, and F0 for a Synthesized Vowel under Cognitive Load, 2018-2021

This dataset contains measures of just-noticeable differences, or JND, of duration (ms), intensity (dB), and pitch or F0 (Hz) for a synthetic vowel. JNDs were measured under 4 acoustic conditions: (1) Audio-only, i.e., with no secondary task, (2) Perceptual load, i.e., with concurrent visual stimuli but no requirement to pay attention to them, (3) Low cognitive load in the form of a 1-back task on visual stimuli, and (4) High cognitive load in the form of a 2-back task on visual stimuli. In addition, the 1-back and 2-back tasks involved either meaningless images or pronounceable nonwords. Performance on the 1-back and 2-back tasks, labelled CL accuracy, was also measured using the d' index from Signal Detection Theory. Below is a summary of the study and its rationale: Dual-tasking negatively impacts on speech perception by raising cognitive load (CL). Previous research has shown that CL increases reliance on lexical knowledge and decreases reliance on phonetic detail. Less is known about the effect of CL on the perception of acoustic dimensions below the phonetic level. This study tested the effect of CL 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 by N-back tasks at two levels of difficulty (one-back, two-back) and under two types of load (images, nonwords). Compared to a control condition with no CL, all N-back conditions increased JNDs across the three dimensions. JNDs were also higher under two-back than one-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 CL on the listening experience can be traced to distortions in the perception of core auditory dimensions.