William F. Dolphin
Dept. of Biomed. Eng., Boston Univ., Boston, MA 02215
Auditory-evoked potentials (AEPs) recorded from the scalp surface are neurogenic potentials arising from the massed discharge of neural populations in response to acoustic stimuli and provide a ``window'' on the physiological basis of auditory processing. AEPs, in particular the transient-evoked auditory brain-stem response (ABR) have been widely used in human clinical settings for the evaluation of auditory functioning. Recently, several new techniques using continuous amplitude-modulated tonal stimuli have been investigated. Many of these techniques take advantage of auditory nonlinearities which result in the auditory system acting as an envelope extractor. This envelope following response (EFR), phase locking of neural discharge to waveform periodicities, has been measuring using two-tone, sinusoidal amplitude-modulated, and multitone, multiple envelope components signals. The EFR offers great promise for frequency specific threshold measurements, especially for low-frequency audiometry and for the examination of auditory processing of complex sounds.