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Providing Some Direction – Beamformers Explained

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1.  Beyond _______, sound is generally considered to be arising from the far field. 1m 1.5m 2m 5m

2.  What is the most common hearing aid technology that improves the signal-to-noise ratio in the near-field? Digital noise reduction Reverberation algorithms Impulse noise management algorithms Directional microphones

3.  What is the internal/external delay ratio that will deliver a cardoid polar plot pattern? 0.5 0.7 1.0 1.3

4.  What is the optimal microphone tilt angle? 0° 10° 20° 35°

5.  Directionality in what frequency region is impacted most by a microphone mismatch? All frequencies Low frequencies Mid frequencies High frequencies

6.  Which polar plot pattern is the best for trying to attenuate noise sources at 90° / 270° Azimuth? Cardoid polar plot pattern Super Cardoid polar plot pattern Hyper-Cardoid polar plot pattern Bi-Directional polar plot pattern (also known as ‘Figure 8’ polar plot pattern)

7.  What are some of the benefits of a multi-channel directional microphone approach? No benefits Restoration of pinna effects when hearing aid microphones are placed behind the ear. Minimization of wind noise in the low frequencies by adopting an omni-directional response and simultaneous directionality in the higher frequencies to optimize speech perception in nosie. Both B & C

8.  Which statement best describes a true binaural beamformer? A binaural fitting in which the directional microphones on each hearing aid operate completely independently of each other. A binaural fitting in which the directional microphones on each hearing aid are connected together into one 4-Mic beamformer to provide a very narrow beam to the front. A binaural fitting in which the directional microphones on each hearing aid are coordinated so that if one hearing aid goes into a directional mode, the other one does too. A binaural fitting in which the directional microphones on each hearing aid are coordinated so that if one hearing aid goes into a directional mode, the other one remains omni-directional.

9.  What are some of the benefits of a binaural beamformer over a monaural beamformer? Better SNR Reduced listening effort, reflected in both subjective and objective measures. Enhanced social interaction All of the above

10.  Which statement best describes a spatial noise canceller? A noise cancellation system that also considers information from the beamformer when applying noise reduction. A noise reduction system that utilises only temporal modulation rate. A system that applies a low-frequency cut to reduce noise. A noise reduction system that considers amplitude fluctuations only.