Using a signal cancellation technique involving impulse response to assess directivity of hearing aids.
The directional microphone systems of modern digital hearing aids are capable of changing their spatial directivity pattern and/or the microphone mode in response to changes in the properties of environmental sounds. These adaptive/automatic features make measurement of a hearing aid's directivity in a given test environment very difficult. Assessing the directivity of such systems requires a signal that can record the system's response while not changing the system's directivity. This paper proposes a method using a signal cancellation technique involving impulse responses to acoustically assess a hearing aid's directivity (referred to as the IR method). The impulse is presumed to be undetectable to the adaptive/automatic system because it contains little energy and a short response could be recorded before the system actually reacts. In the current study, the IR method was evaluated by testing five adaptive/automatic directional hearing aids in noise of various intensities. The results revealed that the IR method was an accurate and repeatable way to assess slow-acting directional systems in noise of varying intensities and fast-acting systems in noise of high intensities.
Wu
Yu-Hsiang
YH
Department of Communication Sciences and Disorders, The University of Iowa, Iowa City, Iowa 52242, USA. yu-hsiang-wu@uiowa.edu
Bentler
Ruth A
RA
D000162:Acoustics; D000465:Algorithms; D001331:Automation; D004582:Electronics, Medical / Q000295:instrumentation / Q000379:methods*; D006310:Hearing Aids; D006801:Humans; D008953:Models, Anatomic; D009622:Noise; D012815:Signal Processing, Computer-Assisted; D013018:Sound Spectrography; D013060:Speech