Rationale

The rationale in GO is chosen because it is well known and tested throughout the world.
 
The implementation of NAL-NL1 in GO (including compression strategy - attack and release times and the adaptation manager) is designed by Oticon. This makes GO a true Oticon hearing aid, which delivers good long-term benefits and quick acceptance for the user and good fitting flexibility for the dispenser.
 
NAL-NL1
NAL-NL1 is a non-linear version of the NAL-RP rationale developed by National Acoustics Laboratories in Australia. The aim of the rationale is to optimize speech understanding and provide the hearing impaired with the same relative loudness in speech signals as a normal hearing person would have.
 
The rationale uses a Speech Intelligibility Index (SII), which was used to optimize insertion gain for 52 different audiograms. Based on these optimizations, the rationale calculates insertion gain at each frequency, based on hearing loss at the specific frequency, three-frequency average hearing loss, audiogram slope and overall speech input.