The minimum monitoring signal-to-noise ratio for off-axis signals and its implications for directional hearing aids

• DOI: 10.1016/j.heares.2017.11.011
• Publication Date: 2017-11-27T17:15:38Z
• Authors: Alan W. Archer-Boyd; Jack A. Holman; W. Owen Brimijoin
• Keywords: Hearing aid; SIGNAL (programming language)

The signal-to-noise ratio (SNR) benefit of hearing aid directional microphones is dependent on the angle listener relative to target, something that can change drastically and dynamically in a typical group conversation. When new target signal significantly off-axis, lead slower orientation, more complex movements, reversals. This raises question whether there an optimal design for microphones. In principle ideal microphone would provide user with sufficient directionality help speech understanding, but not attenuate off-axis signals so strongly orienting was difficult or impossible. We investigated latter part this question. order measure minimal monitoring SNR reliable orientation signals, we measured head-orienting behaviour towards targets varying SNRs locations listeners mild moderate bilateral symmetrical loss. Listeners were required turn face female talker background noise movements tracked using head-mounted crown infrared system recorded yaw ring loudspeakers. appeared randomly at ± 45, 90 135° from start point. results showed as decreased 0 dB -18 dB, first movement duration initial misorientation count increased, then fixation error, finally reversals increased. Increasing increased all SNRs, (above -12 SNR), had little no effect misorientations. These suggest experience some difficulty sources drops below -6 if one intends make usable moving conversation, attenuation should be than 12 dB.