Far-field recorded frequency-following responses: correlates of low pitch auditory perception in humans.

The recent demonstration that auditory frequency-following responses (FFR) can be recorded by signal averaging from the human scalp, opened the way for studies correlating FFR with auditory experience. This report describes FFR amplitude changes as a function of stimulus intensity and the addition of masking noise. The first experiment revealed a high degree of consistency both within and across subjects in the latency, phase and waveform of averaged FFR. This experiment also demonstrated a monotonic relationship between average FFR amplitude and stimulus intensity between 40 and 65 dB SL. Results of the second experiment showed a close correlation between the detectability of a tone in a noise masker and FFR amplitude. FFR amplitude diminishes precipitously as noise intensity approaches or exceeds the threshold for masking of the tone. These results are interpreted as emphasizing the role of neural periodicity mechanisms in the preception of low frequencies.