Automatic detection of frequency changes depends on auditory stimulus intensity

A cortical cognitive auditory evoked potential, mismatch negativity (MMN), reflects automatic discrimination and echoic memory functions of the auditory system. For this study, we examined whether this potential is dependent on the stimulus intensity.

The MMN potentials were recorded from 10 subjects with normal hearing using a sine tone of 1000 Hz as the standard stimulus and a sine tone of 1141 Hz as the deviant stimulus, with probabilities of 90% and 10%, respectively. The intensities were 40, 50, 60, 70, and 80 dB HL for both standard and deviant stimuli in separate blocks.

Stimulus intensity had a statistically significant effect on the mean amplitude, rise time parameter, and onset latency of the MMN.

Automatic auditory discrimination seems to be dependent on the sound pressure level of the stimuli.