Waves Coming and Going

An entry for the Ecotone topic on Coming and Going

It’s been a week of playing with sound. On the laptop that is, where it’s easy to take a recording from a CD (the sound sampled at 44,100 times per second) and open the file in a sound editor and look at the waveforms. If you zoom down far enough, to ever shorter and shorter periods of time, you see the individual sample points, approximating the continuous sound wave. (Dogs must find CD recordings dreadfully lo-fi, being unable to render the upper octaves of their hearing.) That we perceive these pressure waves coming and going as sounds of different frequencies is a marvel.

Outside, a Pacific tree frog, by far the commonly encountered frog around here, is going ‘crickle, crickle’. This is their time in the cycle of the year—plenty of water around to keep them happy and able to wander about freely. At left there is a plot of the sound spectrogram of their call (time is on the x-axis, frequency is the y-axis). Their call pattern is strikingly periodic: a two-part ‘crickle’ every second or so.

It’s cloudy, and I don’t know what the phase of the moon is. But I do know that 29.5306 days from now, it will be at the same phase. Such is the periodicity of this universe.