Procedure for the steady-state verification of modulation-based noise reduction systems in hearing instruments

Hearing instrument verification involves measuring the performance of modulation-based noise reduction systems. The article proposes a systematic procedure for their verification. The procedure has the potential for application in the verification of other signal processing systems, because it is independent of the hearing instrument domain. Its key concept, the separation of abstract and concrete design of test signals, has been adopted from the embedded systems domain. Specifically for modulation-based noise reduction systems in hearing instruments, the article shows a complete implementation of the verification procedure, proposing improvements of existing measurement techniques. To fully cover the verification procedure, a new measurement approach based on maximum length sequences and DFT processing is introduced, revisiting concepts of system identification that came up in the 1970s. These can easily be used with the computational resources of today's microcomputers. Sample measurements with existing hearing instruments demonstrate the verification procedure with different measurement techniques.