Interaural coherence based cochlear stimulation using adapted fine structure processing

A signal processing arrangement for signal processing comprising a bilateral hearing implant system having left side and right side hearing implants with electrode contacts, the arrangement comprising:

• at least one sensing microphone for each of the left side and right side hearing implants configured for sensing a sound environment for that hearing implant to develop a corresponding microphone signal output;
• a filter bank for each of the left side and right side hearing implants configured for processing the microphone signal to generate a plurality of band pass signals for that hearing implant, wherein each band pass signal represents an associated band of audio frequencies, and wherein each band pass signal has characteristic temporal fine structure features and a characteristic band pass envelope reflecting time varying amplitude of the band pass signal;
• at least one interaural coherence analysis module configured to receive input signals from each of the left side and right side hearing implants including the microphone signals and the band pass signals and configured to analyze the input signals to produce an interaural coherence signal output characterizing reverberation-related similarity of the input signals;
• a stimulation timing and coding module for each of the left side and right side hearing implants configured for processing the band pass signals to develop stimulation timing signals, wherein the processing includes selecting from the band pass signals a subset of one or more selected band pass signals, and wherein for the one or more selected band pass signals, the processing includes:
• i. selecting as a function of the interaural coherence signal a stimulation coding strategy from a plurality of different stimulation coding strategies including an envelope-based stimulation coding strategy based on the band pass envelope, and an event-based stimulation coding strategy based on the temporal fine structure features,
• ii. producing the stimulation timing signals using the selected stimulation coding strategy, and
• iii. switching between different selected stimulation coding strategies as a function of changes in the interaural coherence signal;
• and
• a pulse generation module for each of the left side and right side hearing implants configured for processing the stimulation timing signals to develop electrode stimulation signals to electrode stimulation contacts of the left side and right side hearing implants implanted in a patient cochlea for perception as sound.