The auditory N1 component can be recorded to gaps in continuous narrowband noises whose gap thresholds are grossly similar to those obtained psychophysically. The differences found between PGTs and EGTs with different narrowband noise center frequencies call for further investigation of narrowband noise stimuli for the study of temporal resolution.

Middle components (la6tency 8–50 msec) of the averaged auditory electroencephalic response (AAER), evoked by brief duration tone bursts, were recorded from 11 normal-hearing subjects. Latency and amplitude measurements were made on five peaks (N a , P a , N b , P b , and N c ) of the AAER waveforms recorded for 27 experimental conditions: three conditions of stimulus frequency (250, 1000, and 4000 Hz) at each of nine conditions of signal intensity (a no-stimulus control and 10, 20, 30, 40, 50, 60, 70, and 80 dB re: group thresholds). Latency for each peak decreased with increased stimulus frequency, and it tended to decrease slightly with increases in stimulus intensity. Amplitude input-output characteristics varied with stimulus frequency and response peak. In general, the most linear input-output characteristics occurred for the early peaks and high stimulus frequencies. Characteristics for later peaks and lower frequencies tended to asymptote at moderate stimulus intensities. Between-subject variability was not much greater than within-subject variability for the single event auditory evoked potential (AEP). The variance of the AEP, however, was nearly as great (as much as two-thirds) as the variance of the background EEG, despite the large difference between AEP and background EEG amplitude.

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Electrical activity was recorded from adult subjects during four consecutive nights of natural sleep. Ongoing EEG activity was recorded from an electrode on the vertex referred to electrodes on the right and left mastoids. An electrode placed near the outer canthus of each eye was referred to the left mastoid and used to record eye movements (EOG). The early components of the averaged electroencephalic response (AER) were examined during the third and fourth nights, with 50 dB SL clicks at a rate of 9.6/sec presented continuously from a loudspeaker during the entire night. Each average consisted of 1024 responses. Sleep stages were subsequently scored from the EEG and EOG, and AERs were selected for analysis based on predetermined sampling rules. The response during sleep differs only slightly in latency from that found in waking subjects. Latencies of the major peaks remain constant regardless of stage of sleep. Amplitude generally varies with stage of sleep: the deeper the stage of sleep, the smaller the amplitude. REM sleep does not interfere with responsivity and, in fact, may enhance clarity of response. In addition, overall response patterns from stages of sleep compared early in the night to those from the early morning show no evidence of long-term habituation during the course of the night.