Sound is a type of mechanical wave, a longitudinal wave. It is often studied separately, called acoustics, since there are many wave phenomena, although not necessarily unique to sound waves, are relatable since we really on sound for communication.
The following lessons examine some of the more common sound behaviours.
The following lessons examine some of the more common sound behaviours.
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When to sound waves of very similar frequencies interfere, the result is a periodic change in amplitude referred to as beats. The beat frequency is equal to the difference in the frequency of the two sound waves. fbeat = |f2 - f2| Watch the video which explore this concept. |
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Interactive
The following interactive from the work of Walter Fendt, allows you set two wave frequencies and then see the resulting wave,
The following interactive from the work of Walter Fendt, allows you set two wave frequencies and then see the resulting wave,
Experiment
A really simple way to hear beats is to get together with another person with another phone. On your phone have a signal generator app installed. There are many, here being a free one.
Now have both play the same frequency, say 500Hz and stack them. Now increase or decrease one of the apps by 1 Hz at a time and you will here the beats.
Another detailed way to demonstrate is connect both to an oscilloscope. One for each input. Then choose to add the two inputs .
A really simple way to hear beats is to get together with another person with another phone. On your phone have a signal generator app installed. There are many, here being a free one.
Now have both play the same frequency, say 500Hz and stack them. Now increase or decrease one of the apps by 1 Hz at a time and you will here the beats.
Another detailed way to demonstrate is connect both to an oscilloscope. One for each input. Then choose to add the two inputs .
