Randy--
And thus the evolution to cars and rush hours!
Rob
=3D =3D =3D =3D =3D
>Rich and NatureRecordists:
>
>Klas' reply prompts me to add to this thread. In 1999 I had the pleasure
>of working with Dr. Michael Garstang, a meteorologist who was interested
>in recording elephant vocalizations. He pointed out something that all of
>us NatureRecordists have known, but which few of us has really stopped
>to realize: that surface air turbulence and winds have circadian rhythm,
>being minimal at dawn and dusk, and that temperature inversions are
>most apt to occur at such times. Of course, one consequence of temper-
>ature inversion is that sound is "channeled" or "ducted" along the surface=
.
>We also know that low frequencies travel further than high frequencies,
>as evidenced by the spectral difference between the "crack" and "rumble"
>of nearby and distant thunder, respectively. Combine this with the mini-
>mized turbulence, and you have a formula to favor evolution of acoustic
>communication systems which, for long distance efficacy, use low
>frequencies and do so primarily at dusk and/or dawn.
>
>Good recording,
> Randy
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