Question

Q11: You will get the best results by placing the microphone at a pressure antinode. Knowing this and considering you are using a closed tube, where should you place the microphone? Explain. Q12: Does your answer to Q11 depend on the frequency? Explain.

Answer 1

Pressure variations, whether in the air ,the water, or another medium the human ear can detect ,are considered sounds. The human ear drum transfers pressure oscillations, or sound , into electrical signals that our brains interpret as music, speech ,noise, and so on . Microphones are designed to do the same thing.

Have the tube closed at both ends. For some frequency between, say, 200 Hz and 2 kHz, adjust the frequency so that a standing wave exists in the tube.

1) One way to adjust the frequency for a good standing wave is to place the microphone as close to the loudspeaker as possible and adjust so that the amplitude as measured by the microphone is a maximum; recall that this corresponds to the displacement of the air molecules from their equilibrium position being a minimum.

2) A secondary adjustment can be made by placing the microphone at the position of a node in the pressure wave and making small adjustments of the frequency to make the measured amplitude as small as possible.

Yes, it depends on frequency as explained in (1) and (2) steps.

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