Components of the frequency-following potential in man.

The scalp recorded frequency-following potentials (FFP) are a composite of several FFP's which may be distinguished by comparing simultaneously recorded waveforms from vertical and horizontal derivations in response to tones of very low frequently (below 350 Hz). The two most prominent FFP's were designated FFP1 and FFP2. FFP1 was recorded equally well in vertical and horizontal derivations and at a high stimulus intensities tended to be the predominant FFP. FFP2 followed FFP1 usually by about 1.7 msec and was optimally recorded in the vertical derivation. FFP2 threshold was about 10 dB lower than threshold for FFP1 and in several subjects, FFP2 was observed at 25 dB SL. Two other FFP's, a far-field recorded cochlear microphonic potential and a low-amplitude FFP, the latter presumably of neural origin, were also studied.