Frequency-Specific Whole-Nerve Response in Human by Use of Frequency-Modulated Tone

Abstract

A human study of the compound action potential (AP) to frequency-modulated tone (FM tone) was achieved in order to obtain frequency-specific APs using the transtympanic electrode. Clearly recognizable APs were elicited by a downward shift of 20% in the frequency of 515Hz, 1150Hz or 2230Hz pure tone. The latency is greater for lower frequency tones and this latency increase agrees with the traveling delay for the intensity range used in this study. The latency-intensity curves of these three frequencies did not show the convergence with increase in the intensity of tones. The latency at moderate intensity of the FM tone was similar to that for the short tone burst at threshold intenisty. These findings suggest that the FM tone in downward direction can be a frequency-specific stimulus even at relatively high intensities.