Neural coding of perceptual temporal asymmetry for sounds with rising vs. falling intensity envelopes in non-attentive and attentive listening conditions

Abstract

Behavioral studies have shown that ramped sounds are judged to be louder and longer than damped sounds. Here we employed magnetoencephalography (MEG) to examine cortical processing of the perceptual temporal asymmetry. The participants were 6 normal-hearing right-handed male adults. The synthesized stimuli included three kinds, pure tone, piano note, and broadband noise with time-reversed intensity envelopes for the ramped vs. damped comparison. Each stimulus was 200 ms. In the non-attentive condition, subjects were instructed to watch a silent movie and ignore the randomly presented tones. In the attentive condition, listeners were required to judge whether the first or the second of paired sounds was longer. The stimuli were presented at 50 dB SL. The behavioral results replicated previous temporal asymmetry findings for all three types of stimuli. There were significant effects of stimulus type and stimulus order in the MEG ON and OFF responses. Despite the stimulus type effect, the ramped tonal stimul...