Three studies were performed to investigate the effects of auditory st
imuli (pure tones and environmental noise) of different intensities on
surface EMG activity recorded over five facial muscle regions (M. fro
ntalis lateralis, M. corrugator supercilii, M. orbicularis oculi, M. z
ygomaticus major, M. depressor anguli oris). The results show that wit
h presentation of tones and noises of high intensity (> 85 dB) strong
facial EMG reactions over muscles of the upper face (M. frontalis late
ralis, M. corrugator supercilii, M. orbicularis oculi) were evoked. Am
ong environmental noises of different valence but the same intensity,
baby's crying evoked EMG reactions over facial muscles in the mouth re
gion, possibly indicating that the subjects demonstrated expressions o
f dislike during this particular stimulation. It is also discussed whe
ther facial EMG reactions to auditory stimulation of different intensi
ties could be connected to changes in muscle tone of the middle ear mu
scles. The contraction of these muscles modulates sensitivity to audit
ory stimulation. Thus, facial EMG activity of the muscles of the upper
face could serve as an indicator of sensitivity to external auditory
stimuli. However, the evaluation of pleasant and unpleasant emotional
reactions in response to auditory stimulation seems to be impossible.