Using a signal cancellation technique to assess adaptive directivity of hearing aids.
The directivity of an adaptive directional microphone hearing aid (DMHA) cannot be assessed by the method that calls for presenting a "probe" signal from a single loudspeaker to the DMHA that moves to different angles. This method is invalid because the probe signal itself changes the polar pattern. This paper proposes a method for assessing the adaptive DMHA using a "jammer" signal, presented from a second loudspeaker rotating with the DMHA, that simulates a noise source and freezes the polar pattern. Measurement at each angle is obtained by two sequential recordings from the DMHA, one using an input of a probe and a jammer, and the other with an input of the same probe and a phase-inverted jammer. After canceling out the jammer, the remaining response to the probe signal can be used to assess the directivity. In this paper, the new method is evaluated by comparing responses from five adaptive DMHAs to different jammer intensities and locations. This method was shown to be an accurate and reliable way to assess the directivity of the adaptive DMHA in a high-intensity-jammer condition.
Wu
Yu-Hsiang
YH
Department of Speech Pathology and Audiology, University of Iowa, Iowa City, Iowa 52242, USA. yu-hsiang-wu@uiowa.edu
Bentler
Ruth A
RA
D000161:Acoustic Stimulation; D000465:Algorithms; D004867:Equipment Design; D006310:Hearing Aids; D006801:Humans; D008422:Materials Testing / Q000379:methods*; D009622:Noise / Q000009:adverse effects; D010363:Pattern Recognition, Automated; D010470:Perceptual Masking; D015203:Reproducibility of Results; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation*; D013017:Sound Localization; D013018:Sound Spectrography; D013061:Speech Acoustics; D013065:Speech Intelligibility; D013067:Speech Perception; D013997:Time Factors