Uncomfortable loudness level on auditory-evoked responses and spontaneous activity in auditory pathway

UCL (Uncomfortable loudness level) is one of the important factors on hearing aid fitting and sound design of a notification sound signal. UCL can be measured by asking for subjective judgment. As this experiment needs a great deal of time with loudly sound, the heavy load is applied to the participants. Objective UCL estimation method without the load is looking for.In this study, to construct the neurophysiology index of uncomfortable loudness level, auditory evoked potential and auditory evoked neuro-magnetic response field which reflects auditory information processing, and level dependency characteristics of spontaneous brain magnetic field's alpha wave which reflect comfort of auditory stimuli, were conducted, the activity part on auditory pathway, which uncomfortable level sensitive reacts, were observed.