A method of signal processing to generate hearing implant stimulation signals for a hearing implant system includes transforming an input sound signal into band pass signals each representing an associated frequency band of audio frequencies. The band pass signals are processed in a sequence of sampling time frames and iterative steps to produce a noise power estimate. This includes using a noise prediction model to determine if a currently observed signal sample includes a target signal, and if so, then updating a current noise power estimate without using the currently observed signal sample, and otherwise updating the current noise power estimate using the currently observed signal sample. The noise prediction model also is adapted based on the updated noise power estimate. The hearing implant stimulation signals are then developed from the band pass signals and the noise power estimate.