Re: [Phys-L] Resonance with tuning forks vs small speakers

[Paul Nord <Paul.Nord@valpo.edu>]

Zeke,

For starters, the tuning fork is really bad at radiating sound energy.
They make almost no noise at a distance.  The tube acts much like the body
of a stringed instrument in helping the motion of the string couple to the
air.  Phones, on the other hand, would need to work hard to design a
speaker that transmits anything to the air.

Take a look at the 39 minute mark of this video:
https://www.youtube.com/watch?v=ADgihdzVSRY

As for the human perception of "amplitude increase" it may be related to
the logarithmic nature of human hearing.  Ten times more energy in the
sound wave doesn't sound 10 times louder.

Paul


On Fri, Oct 28, 2022 at 2:03 PM Zeke Kossover via Phys-l <
phys-l@mail.phys-l.org> wrote:

> Howdy Physicists!
>
> As a resonance activity, I bring a vibrating tuning fork towards a tube
> that is open at one end and closed at the other. When tuned correctly, the
> air in the tube loudly resonates.
>
> Since tuning forks are expensive and every student has a phone with a
> speaker, I've tried running the activity with a frequency generated by
> their phone. To my ears, the sound generated by their phones is way louder
> than the tuning fork, but when I put the phone next to the tube, the
> amplitude increase is way less.
>
> I wonder why they are so different. Do any of y'all have ideas?
> --
> *Marc "Zeke" Kossover | Educator, Teacher Institute*
> zkossover@exploratorium.edu
> Museum: Pier 15, San Francisco, CA 94111
> Mailing: 17 Pier, Suite 100, San Francisco, CA 94111
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