Minimum intensities of white noise which produce the vasomotor response

Twelve normal hearing awake adult subjects were tested to determine the minimum intensities of white noise which produce a detectable change in digital blood flow. A digital plethysmograph was utilised to detect and record these changes. The stimulus intensity was adjusted in 5 dB increments, beginning at an intensity below voluntary threshold, for a total of four data trials. The range of minimum intensities producing the response was 20 to 60 dB HTL, however, there was no significant variation in the mean intensities required to produce the response from trial to trial (F = 0.48, df-3.30, N.S.). The results support further research into the development of peripheral vascular techniques in determining the presence or absence of hearing for individuals who cannot be tested by voluntary audiometry.