RELATION BETWEEN SOUND INTENSITY AND AMPLITUDE OF AER AT DIFFERENT STIMULUS FREQUENCIES

Summing computer technique was employed to study the relationship between sensation level and phons, and peak to peak (N2 P2) voltage of the auditory evoked response at different frequencies. The relationship of the frequencies 125, 500, 1000, 2000, 4000, and 8000 Hz was studied at five intensities (20, 40, 60, 80, and 100 dB) by sensation level and by phons. There has been some controversy as to whether the power law, a straight line in double logarithmic coordinates, is a better fit than a linear relation between the voltage of the N2 P2 peak amplitude and decibels (sensation level and phons). Our observations, however, led us to believe that the linear relation is the more accurate fit. The data also revealed a marked decrease in slope of the function from 500 to 8000 Hz. Slope ranged from 1.1 at 125 Hz to almost none (constant) at 8000 Hz. Peak to peak amplitude ranged from 3.8 μV at 20 dB to 8.9 μV at 100 dB for 500 Hz, to only 1.6 μV at 20 dB to 3.4 μV at 100 dB for 8000 Hz. The consistent growth in peak to peak amplitude with each increase in sound intensity at the low frequencies did not maintain above 2000 Hz. At 8000 Hz, for example, the average amplitude of N2 P2 was less at 100 dB than at 80 dB. As also reported in an earlier study, a consistent decrease in the peak to peak amplitude was observed under both conditions as the frequency was increased. © 1969, Acoustical Society of America. All rights reserved.