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Resonant Excitation of Standing Sound Waves in a Pipe

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A speaker, placed at the opening of a tube is driven at various frequencies. When the sound is a resonant frequency of the system, the sound becomes very loud.

Title: Resonant Excitation of Standing Sound Waves in a Pipe

Keywords: resonant, excitation, standing, sound, waves, pipe, loud, noise, interference, constructive, destructive

Category: Sound and Music

Author: Matthias Liepe

Producer: Cornell University

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A speaker is connected to a function generator, and the speaker is placed at the end of a pipe. The function generator is used to drive the speaker at a given frequency. The first frequency heard loudly (a resonant frequency) is at 181 Hz. Subsequent resonances can be excited by increasing the frequency by half this value. A frequency resonates when the waves in the pipe constructively interfere. Off resonance, no sound (or very little sound) is heard from the pipe, because the waves are destructively interfering.