The human frequency-following response: its behavior during continuous tone and tone burst stimulation.

The frequency following response (FFR) in humans has been elicited by continuous tones as well as tone bursts. The responses were observable over a range of frequencies extending from 70 c/sec to greater than 1.5 kc/sec. The threshold for the continuous response has a mean of about 40 dB SL and is perhaps several dB lower for the burst response. The response threshold as a function of sound pressure level (SPL) increases rapidly at frequencies below 125 c/sec and above 1 kc/sec. These thresholds are particularly sharp at the lower frequencies. Narrow-band noise that just produces subjective tone masking also masks the FFR. The latency of the FFR is about 6 msec when the tone burst intensity is 30 dB over FFR threshold. Comparison with click response latencies indicates that the onset of the FFR corresponds with early waves IV and V.