Fig. 6.

Békésy threshold as a function of the EDPT. The measurements shown are for EDPT derived from conventional pressure in a closed sound field (▵) and for EDPT derived from umbo vibration measurements in an open sound field. n = 30 I/O functions from 14 subjects; f₂ = 4–9.5 kHz. Regression lines for both the sound (dashed line) and the vibration (solid line) data have fixed slopes at 1.18 dB/dB, equal to the value derived by Boege and Janssen (19) for pressure DPOAEs. Their data set contained 4,236 points and exhibited a standard deviation of the Békésy thresholds from the regression line of 10.9 dB SPL. Here, the standard deviation of the Békésy thresholds from the regression line is 16.7 dB SPL for the sound pressure and 8.6 dB SPL for the umbo vibration measurements.