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Standing sound waves and normal modes
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Sound waves in a fluid may be described either in terms of the displacement or in terms of the pressure variation of the fluid.
In a standing wave, a pressure node is always a displacement antinode, and a pressure antinode is always a displacement node.
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Sound wave resonance depends on the instrument |
Open pipe: both ends are open
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Sound wave resonance depends on the instrument |
Stopped pipe: one end open and the other closed
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Resonance and sound |
Resonance occurs when a periodically varying force is applied to a system with many normal modes.
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Wave interference ˇ destructive or constructive |
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Slightly mismatched frequencies cause audible ˇ°beatsˇ± |
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Beats |
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Angular beat frequency:  |
Beat frequency:  |
Group velocity:  |
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