Reaction-time procedure for measurement of hearing. II. Threshold functions

The reaction-time (RT) procedure applied to the measurement of suprathreshold functions in the preceding paper may also be used to measure threshold. This paper examines threshold contours measured by the RT procedure in human and monkey subjects with normal and impaired hearing. In the human subjects, thresholds obtained using the RT procedure closely paralleled those obtained in the clinic but were an average of 2.7 dB lower; RT thresholds were an average of 5 dB above thresholds obtained in a forced-choice procedure. Thresholds obtained from monkey subjects paralleled the normal human contours within the human frequency range of hearing, but were slightly higher at frequencies below 4 kHz and lower at frequencies above 4 kHz. The monkeys' hearing extended approximately 1 1/4 octaves above the humans'. Thresholds measured using the RT procedure in human and monkey subjects agreed well with thresholds previously reported in the literature. The effects of sound presentation and calibration procedures on the shape and position of the threshold contours are examined in an appendix.