Exam Preview for 12616: Directionality Revisited Wed, Mar 4, 2009 a

Directionality Revisited

Please note: exam questions are subject to change.

1. What are the measures that are taken by our DSD system Input at both microphones Input at omnidirectional microphone Input at directional microphone Signal to noise ratio All of the above
2. Many people with hearing loss need a higher signal to noise ratio (SNR) than normal hearing people would in order to achieve the same level of speech recognition. One set of data from the course suggested _____ SNR is needed to perform as well as normal h 14dB 3dB 22dB 8dB equal performance cannot be achieved, regardless of SNR
3. The hierarchy with the DSD is as follows intelligibility, perceptual stability, comfort comfort, perceptual stability, intelligibility perceptual stability, intelligibility, comfort intelligibility, comfort, perceptual stability There is no hierarchy
4. A general rule of thumb relating to expected benefit from directional hearing aids says that the unaided speech recognition in quiet should be at about 88% 28% 68% 48% 10%
5. Which of the following is NOT listed as a factor in performance on speech in noise testing: speech materials use of insert earphones type of background noise test setup reverberation
6. Which of the following "allows low frequency sounds coming from behind the wearer to pass through without attenuation" : a directional microphone an omni-directional microphone 13 heavy tubing venting None of the above
7. In comparing directional responses to omni directional responses , which of the following statements are true with regard to low frequency roll-off: the greatest loss of sensitivity is noted when microphones are very close together (4mm or less separation) the greatest loss of sensitivity is noted when microphones have a great separation (12mm separation) the omni directional mode shows equal loss of sensitivity to a 4mm microphone separation the omni directional mode shows equal loss of sensitivity to a 12mm microphone
8. On Radius products, the hearing threshold at what frequency determines the amount of low frequency roll-off applied: 1KHz the Pure Tone Average is used 8KHz 250Hz 500Hz
9. Relating to the above rule, if the patient's threshold at said frequency is 55dB, which rule would apply: 6dB roll-off no roll-off 10dB roll-off 12dB roll-off
10. What polar pattern does the directional microphone system in Radius products use: adaptive cardiod bi-directional diffuse (hypercardioid)