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Thread: Note amplified in shower

  1. #1 Note amplified in shower 
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    The other day I was humming a song in a shower. I noticed that one of the notes that I hummed was significantly amplified by the shower. That note was "amplified" in the sense that it echoed and sounded louder. So my question is, what was exactly happening?

    I came up with a theory to explain it but its probably incorrect. I was thinking that if I hum a note, facing the shower wall, then the note would be amplified if the distance between the two walls is equal to (or an integer multiple of) the notes wavelength? Is this correct at all.

    Thanks


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  3. #2  
    Forum Freshman Nabla's Avatar
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    Since energy is always conserved, the louder note you heard had not technically been amplified, the others had simply been attenuated more. The acoustics of your shower cubicle are probably very complicated and have many factors affecting them, and an accurate analysis would be a very deep subject.

    However whats basically happening is that more soundwaves of that particular frequency are reaching your ears than others (i.e. this is a resonant frequency of the cubicle). The reason for this is that material properties like absorption ratio are frequency dependent, reflecting more of one frequency than another. The particular geometry of the chamber would make a difference, and the direction and loudness of your own whistle could vary with frequency somewhat as well.


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  4. #3  
    Forum Ph.D.
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    Wrong Nabla, SteveC is correct , what is happening is called resonance.the sound waves bounce back and forth and add up if the wave length is a multiple of the distance thus increasing the amplitude of the tone .
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  5. #4  
    . DrRocket's Avatar
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    Quote Originally Posted by fizzlooney
    Wrong Nabla, SteveC is correct , what is happening is called resonance.the sound waves bounce back and forth and add up if the wave length is a multiple of the distance thus increasing the amplitude of the tone .
    Right. And there are standing waves created in the small enclosure that result in local amplification of the original signa.

    From a pure energy standpoint, the water droplets in the air in a shower stall should serve to damp sound waves and transform some of the acoustic energy into heat. But the effects of the small enclosure, multiple reflections, and creation of standing waves dominate.

    There is an interesting demonstration that can be given in a closed room if you hve a generator that can produce a pure sine wave. You generate a tone at a reasonably high frequency and then standing waves, with peaks and troughs are established. By moving your head a short distance you can detect the difference between the peaks (loud) and troughs (soft).
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  6. #5  
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    Cool

    Thanks guys
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