Bin Zhou
David M. Green
Psychoacoust. Lab., Psychol. Dept., Univ. of Florida, Gainesville, FL 32611
The effect of standing waves in the ear canal on the intrasubject reliability of pure-tone thresholds was investigated. Sound was transmitted to the ear canal through a hard-wall source and a 3-cm plastic tube. This created a standing wave field between the hard-wall source and the eardrum. In response to a broadband stimulus, the measured sound pressure at the entrance to the ear canal showed several maxima and minima for frequencies between 7000 and 14 000 Hz. Thresholds were measured at three frequencies where successive maxima and minima occurred and also at 1000 Hz. Four subjects were tested. The intrasubject reliability of the thresholds was tested across five sessions with the hard-wall source located at the same position or moved by as much as (plus or minus)0.5 cm. Thresholds were not significantly different across the sessions when the hard-wall source had the same position. The movement of the hard-wall source across the five sessions resulted in significant changes in the high-frequency thresholds ((plus or minus)3 dB), but not in the low-frequency thresholds ((plus or minus)0.5 dB). [Research supported by NIH.]