Analysis of spatiotemporal pattern correction using a computational model of the auditory periphery

Area of Science:

• Auditory Neuroscience
• Signal Processing
• Hearing Aid Technology

Background:

• Spatiotemporal pattern correction (SPC) is a proposed hearing aid algorithm to address altered auditory nerve responses.
• Theoretical models suggest SPC could improve speech intelligibility by compensating for phase and delay differences.
• Preliminary studies showed listeners preferred unprocessed speech, indicating issues with the SPC scheme.

Purpose of the Study:

• Determine the cause of poor experimental performance of the SPC scheme.
• Identify contexts where SPC may offer benefits for hearing aid users.
• Evaluate the effectiveness of an improved SPC algorithm.

Main Methods:

• An improved SPC algorithm was tested using a computational auditory model with synthesized vowels at various sound pressure levels (SPLs).
• Auditory nerve responses in an impaired model were compared to a healthy model for spectrotemporal similarity.
• Analyses included synchronized neural firing rates and relative phase response of auditory nerve fibers.

Main Results:

• SPC improved relative phase response at low SPLs but decreased spectrotemporal response similarity and neural synchrony.
• Identified technical issues: non-flat filterbank response, incorrect frequency corrections due to neural synchrony spread, and induced frequency modulations.
• The algorithm's performance was limited by fundamental technical and conceptual problems.

Conclusions:

• Despite identified issues, SPC demonstrated a benefit for an error metric at low SPLs.
• Phase adjustment may occur at the cost of other auditory processing metrics.
• SPC might be beneficial for processing low-level speech signals in hearing aids.