Frye FONIX 7000 - Manual (Page 199)

Fitting Formula Tables
191
1/3, 1/2, 2/3 Gain
The 1/3-2/3 Insertion Gain Hearing Aid Selection Guide
by: Robert Libby
Hearing Instruments vol 37 #3, 1986
Required insertion gain is calculated as follows:
FREQ. INS GAIN INS GAIN INS GAIN
(Hz) (dB)
(dB) (dB)
(2/3 rule) (1/3 rule) (1/2 rule)
250 2/3 HTL - 5 dB 1/3 HTL - 5 dB 1/2 HTL -5 dB
500 2/3 HTL - 3 dB 1/3 HTL - 3 dB 1/2 HTL -3 dB
750* 2/3 HTL
1/3 HTL 1/2 HTL
1000 2/3 HTL 1/3 HTL 1/2 HTL
1500* 2/3 HTL 1/3 HTL 1/2 HTL
2000 2/3 HTL 1/3 HTL 1/2 HTL
3000 2/3 HTL 1/3 HTL 1/2 HTL
4000 2/3 HTL 1/3 HTL 1/2 HTL
6000 2/3 HTL - 5 dB 1/3 HTL - 5 dB 1/2 HTL -5 dB
8000* 2/3 HTL - 5 dB 1/3 HTL - 5 dB 1/2 HTL -5 dB
Note: Frequencies marked by an asterisk ( * ) are
interpolated because the article does not reference them.