P300 from auditory stimuli: intensity and frequency effects.

Auditory stimulus intensity (45, 60, 75 dB SPL) and standard/target frequency (250/500) and 1000/2000 Hz) were manipulated factorially to assess their effects on the P3(00) event-related brain potential (ERP). For the target stimuli, intensity increases produced reliable increases in P3 amplitude and decreases in peak latency. P3 latency at the lowest intensity level was marginally longer for the low frequency condition. For the standard stimuli, intensity increases produced reliable P3 amplitude increases, low frequency stimuli yielded smaller components than high frequency stimuli, and several interactions with the electrode factor were obtained. P3 latency decreased as intensity increased, and low frequency tones produced longer latencies than high frequency tones. The N1, P2, and N2 components from both stimulus types generally were affected in the same manner: intensity increases producing larger amplitudes and shorter latencies, with some effects of tone frequency also observed. The findings suggest that auditory stimulus parameters contribute to both P3 amplitude and latency measures in important ways and are discussed in relation to the use of ERPs in applied contexts.