A long-latency comnponent of the averaged evoked potential recorded from the human scalp varied in close relationship with subjects' perceptual reports in an auditory signal detection task. Detected signals evoked potentials several times larger than did undetected signals, falsely reported signals, or correctly reported nonsignals. The threshold signal intensity at which detection perfornmance exceeded chance levels was identical with concurrently obtained electro-physiological measures of threshold.

To test the adequacy of French regulations for sound isolation in buildings, subjects were asked to rate their annoyance with samples of music filtered by electronic "insulation curves" representing different party walls. The insulation curves differed in their shape but all provided an A-weighted le•,el difference of 51 dB with a pink noise source, measured over a 1/3-octave bandwidth of 40 Hz-10 kHz. However, the different insulation curves did not provide the same degree of sound isolation with various music samples due to source spectral differences. A statistically significant correlation was observed between annoyance and the A-weighted level difference ratings of the insulation curves when bandlimited pink noise (125 Hz-4 kHz)was used as a source. This correlation was not present when broadband (40 Hz-10 kHz) pink noise was used for the performance rating. Subjects showed a preference for insulation curves with steeper slopes (9 and 12 dB/oct), thus preferring a greater relative attenuation at higher frequencies. Additionally, the presence of coincidence dips was found to have an effect on subject preference that appeared to depend upon both the frequency range at which they occurred and the slope. The bandwidth of the music signals and the intelligibility of speech in the intruding sounds were also found to influence the annoyance ratings. These results indicate that the level difference method for rating sound insulation could better predict occupant response if the above results were accounted for in the procedure.

The apparent loudness of a tone pip can be increased by a prior toneburst presented to the contralateral ear. A listener receives two tone pips S1 and S2 separated by 1.5 sec, and he adjusts the intensity of S2 to equal S1 in loudness. When a toneburst to the contralateral ear precedes S1 by an interval ΔT, the loudness of S1 is enhanced by as much as 14 dB. This enhancement (1) increases as the frequency of the contralateral toneburst approaches S1 from above or below; (2) decreases to zero as ΔT is increased up to 1 sec; (3) increases as the contralateral stimulus duration is increased up to 200 msecs; and (4) is monotonically related to contralateral intensity greater than 70 dB SPL. In a particular case with S1 at 8 kHz, changing the frequency of the contralateral toneburst from 8 to 8.2 kHz cut the loudness enhancement to one-half. The possible physiological basis and psychological significance of this phenomenon will be discussed.

Twenty-eight audiologically normal adult subjects participated in a study designed to assess how well six noise-rating indices would predict the annoyance caused by 3-min recorded samples of traffic noise obtained from both nominally constant-speed and stop-and-go traffic. The study was performed in a laboratory simulating a home environment. Annoyance judgments were obtained through the use of a magnitude estimation technique involving a 10-point scale. Subjects were also asked if they could accept each of the 24 traffic sounds if heard on a regular basis in their homes. Data obtained indicate that the simpler noise-rating indices, such as the average sound level and the level exceeded 10% of the time, predict annoyance as well as, if not better than, complicated schemes incorporating a measure of either variability or rate-of-change of levels with time. Thus it appears that the measurement and computational burdens associated with these complicated schemes are unwarranted.

The apparent loudness of a tone pip can be increased by 15 dB or more if it is preceded by a tone burst to the contralateral ear. The experiment is done by delaying the pip, S•, by a variable time, AT, after the offset of a contralateral tone; the listener assesses the loudness of S• by adjusting the intensity of a second tone pip, S•., that follows S• by 1500 msec. Some parametric explorations of the phenomenon are reported here.