# Physics Project : Sound

1. Mar 29, 2005

### itmpls

Purpose:

# to study the production of sound waves
# to build a device that will produce different sounds
# to play a tune of your device
# devise a way to make sound from the material
# be able to make different sounds with the material

Materials:
# any material you can find around your home

Procedure:

# device must be able to produce at least 5 different frequencies
# you can not use any conventional musical instrument in part or in whole
you must be able to play your device
# write a report, complete with diagrams, on how your device works
# include these terms in your report:

resonance tone amplitude
timbre frequency wavelength

Any ideas? Spoons? Rubber Bands?

2. Mar 30, 2005

### gschjetne

It's up to you how to figure out how to build the device, but I'd suggest some kind of tube closed at one end, where you can vary the length, $l$, in order to get a certain wavelength, $\lambda$
$$l = \frac{1}{4} \lambda$$

3. Mar 31, 2005

### itmpls

The instrument I made is similar to that of a violin but different because it’s in a rectangular shape. Without the block of wood, the string being plucked would make a weak sound. But when the block of wood is added, the sounds resonate and there’s more amplitude.
When I pluck at the string, the vibration creates compression waves in the air that result in sound, according to the frequency of the waves. The frequency can be changed slightly by adjusting the tension of the string (in this case you would have to wrap the line tighter around the nail).

The wavelength is twice the length of the string. The shorter the wavelength, the higher the frequency tone.

is this correct?

4. Mar 31, 2005

### gschjetne

This is correct. In most cases you won't have to worry about the speed of sound being proportional to density of the medium, since you probably won't get enough variation in the frequency to hear the difference, even if you climb to a mountain.

A cool experiment my Physics teacher made on resonance was submerging a glass tube into a graduated cylinder filled with water, and holding a tuning fork over the tube. He could vary the lenth of the part of the tube not submerged into the water, in order to find the resonant wavelength with the specific frequency of the tuning fork. This way he could indirectly calculat the speed of sound.

Maybe it would be cool to get your diving goggles on and try this at the bottom of a pool, to see how the speed of sound varies by the density of the medium.