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Unformatted text preview: ME360 Winter 2011 HW #6 1. Turning up volume too high often creates the squealing sound from microphone/speaker. This is a feedback system gone unstable and we can analyze it (in a very rough way). Figure 1 shows the schematic of the speaker/microphone system. First we need to identify the dynamic system components. Microphone-speaker is a dynamic system which can be modeled as a band-pass filter that amplifies certain (audible) frequencies. In transfer function form, it can be written as ? ¡ ( ¢ ) ≅ £¢ ( ¤ 1 ¢ + 1)( ¤ 2 ¢ + 1) where £ ≥ is the amplifier gain to adjust the sound volume. The sound from the speaker propagates through the air and it is picked up by the microphone. The sound arriving at the microphone is an attenuated and delayed version of the original sound that emanated from the speaker. More specifically, the microphone picks up a fraction of 1 ¥ 2 of the speaker acoustic pressure, delayed by the time it takes for the sound to travel the distance ¥ . We may (linearly) approximate the sound propagation from the speaker to the microphone as a ....
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- Winter '11
- Machining Center