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Cool. So if it was a string instead of a column of water, it would just be an unmoving straight line (or points equidistant from the speaker), depending on where it was in the cycle it was captured by the strobe.

Glad it helped.

Oops, sorry, you posted while I was posting this below.
I'll add some more shortly -

We often think of waves as they usually drawn, as an x-y plot. This also
is the same thing you see on an oscilloscope and chart recorder.
The only waves that actually looks like that (that I can think offhand),
are water waves like on the ocean, and a rope being shaken from one end.

In a soundwave, the air does not move from side to side or up and down;
in other words it does not move at right angles to the direction of travel.
The sound can spread out to the side, but the air motion is in the direction
of travel. The air moves towards and and away from the source. The soundwave
is an alternating series of compressed and rarefied regions of air.
If you could freeze a soundwave and walk along it in the direction of travel
with a pressure gauge, you would see the air pressure rising and falling as
you moved along it. If you now plot these pressure readings with pressure on
the vertical axis, you get the familiar sine wave shape, if the sound is of
a pure frequency.

The wave seen in the water stream is more like a plot of a wave, rather than
an actual wave. It is in effect a plot of the motion of the hose. The water
stream is much like the paper strip in a chart recorder (like a polygraph or
electrocardiograph, and the hose tip is like the chart recorder pen.

Last edited by megafiddle; 03/15/13 07:27 PM.