A
hearing aid device providing instantaneous
gain compression for sound signals and
adaptive control of nonlinear
waveform distortion, the device comprising: (a) at least one bandpass nonlinearity (BPNL)
amplifier comprising a first bandpass filter, a second bandpass filter, and a memoryless nonlinear (MNL) compressive audio
amplifier configured to receive a sound
signal from the first bandpass filter and provide an MNL compressive audio
amplifier output to the second bandpass filter, wherein the MNL compressive audio amplifier is configured to produce the MNL compressive audio amplifier output by providing memoryless
gain compression directly on a sound
signal that is (1) received from the first bandpass filter and (2) exhibits instantaneous amplitudes greater than a compression threshold, the BPNL amplifier thereby producing a desired
gain compression on the received sound
signal at an output of the second bandpass filter, and (b) a controller in communication with the BPNL amplifier, the controller being configured to adjust the compression threshold of the MNL compressive audio amplifier. Adjustment of the compression threshold in each BPNL amplifier may be achieved at least partially in response to a
user input and / or to sound signal changes. By adaptively controlling the compression threshold, performance of the device can by optimized to match its environment.