Table 1.

Audiometric curve configuration classification.

Curve configuration	Definition
Flat	High, middle and low frequencies differ in less than 10 dBHL
Sudden drop in the high frequencies	The mean difference at 4.000, 6.000 and 8.000 and the mean value at 500, 1.000 and 2.000 Hz is higher than 25 dBHL, or the difference between any octave of a frequency is higher than 25 dBHL
Mild drop in the high Frequencies	The mean difference at 4.000, 6.000 and 8.000 and the mean value at 500, 1.000 and 2.000 Hz is between 10 and 24 dBHL
Residual	Remaining in the low frequencies
U type	Mid-range frequencies are worse than their high and low counterparts in 15 dBHL or more
Ascending	Low frequencies are worse than high frequencies in 10 dBHL or more

Source: West China University of Medical Sciences, China e Manchester University, England.