Facial electromyographic reactions and autonomic activity to auditory stimuli.

This study explored whether high- and low-intensity auditory stimuli evoke different facial electromyographic reactions and autonomic responses. Subjects were repeatedly exposed to 95-dB and 75-dB tones (1000 Hz, 40 ms rise and fall times) while their facial electromyograms from the corrugator and zygomatic muscle regions, heart rate, skin conductance responses, skin conductance half recovery time and ratings were measured. The 95-dB tone evoked a "negative" reaction with increased corrugator activity and an autonomic response pattern that carried aspects of a defense reaction, that is, slowly habituating skin conductance responses with retarded recovery rate and an initial tendency to heart rate acceleration. Furthermore, the 95-dB tone was rated as unpleasant. The 75-dB tone elicited an orienting response indicated by a distinct heart rate deceleration and fast habituating skin conductance responses with a relatively short recovery time. Thus, the present study demonstrated that the facial electromyographic technique is sensitive to simple environmental stimuli such as auditory stimuli and that the facial response is consistent with the autonomic response patterns and the experience of the stimuli.