1. WDRC
Provides compression prescribed by the selected fitting target.
2. Semi-linear
Reduces compression ratios prescribed by the selected fitting target by reducing the gain for soft inputs and increasing gain for loud inputs. Both WDRC and semi-linear modes use compression limiting to control maximum output, for the least distortion (most commonly preferred by hearing aid wearers).
3. Linear
Provides a compression ratio of 1:1, setting the gains for soft and loud inputs to the same targets as for moderate level. In this mode, Soft Peak Clipping and Hard Peak Clipping are options for limiting the output of the hearing aid. Despite that both options create more distortion in the output of the hearing aid (Hard Peak Clipping creates the most) it is sometimes preferred by those with severe and profound hearing losses.