Click for larger viewI threw this quick page together after someone on the residence organ list asked about 'pipe beats'. As an example I have both a picture and a sound clip of two pipes 'beating' as they come closer in pitch.
Click here to download pipe_beats.mp3
In the sound clip you first hear middle c. Then after a few seconds the c one octave above is played. It's a little flat and you can hear the sound 'wavering' or 'beating'. You then hear me tapping on the tuning collar raising the pitch. As each tap occurs the beats slow down. At the end of the clip my digital tuner claimed the pipes were in tune but a listen shows they were still slowly beating so the tuning is not perfect.
This image shows the waveform that makes up the sound clip. You can see first the middle 'c' and then when the octave comes in. You can see the distance between the peaks increase as the beats slow down.
Neat stuff?