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Date: Wed May 15, 2013 4:10 pm ((PDT))
Hi Chris, I'm afraid I don't have access to a PDF - the article is in
copyright to Wiley and can be purchased from here:
INFRASONIC COMPONENTS IN THE SONG OF THE CAPERCAILLIE TETRAO UROGALLUS
http://onlinelibrary.wiley.com/doi/10.1111/j.1474-919X.1979.tb05021.x/abstr=
act
Ibis Volume 121, Issue 1, pages 95-97, January 1979
However, from memory, this bird emits true infrasound, i.e. components belo=
w
20Hz, well below the cassowary example (although maybe this is just a case=
of needing better gear - the cassowary is a bigger beast and might be able=
to produce lower frequencies). The sound spreads into the audible range,
above 20Hz, which is what we humans hear. The best recordings of
Capercaillie I've ever heard were made by Roger Boughton in Scotland, using=
a Sennheiser MKH105 or MK110, a 'military' spec mike that can capture just =
a
few Hz. With all respect to Klas, his recording just does not compare.
Forget about using a parabola to record these birds properly: the lower the=
frequency, the longer the wavelength, and by the simple physics of
diffraction and reflection you can calculate that to capture 20Hz, the
reflector needs to be at least 56 feet in diameter - instead use a decent
open mic and place it close up - takes many hours of fieldcraft but the
results stand the test of time.
Richard Ranft
The British Library
London
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