> Actually, the fundamental frequency of the Lesser Horseshoes Bat
> echolocation calls is 55 kHz! The most intense component is however
> the second harmonic at 110 kHz.
Raimund,
I'm doing a long term survey on a LHS roost using video and sound
recordings but have never been able to distinguish the LHS 55KHz
subharmonic from the HD detector subharmonic. Theoretically there is a
3dB per metre differential between 55HZ and 110HZ due to air
absorbtion - in other words at 5 Metres, a 15 DB "boost" to the lower
frequency.
For the record, the excess air attenuation (over inverse square) at
110KHz is about 7dB per metre, so in practice even the bats probably
can't hear themselves at 5 metres.
The other distinguishing feature would be that a bat 55KHz would show
half the doppler shifts compared to 110Hz, while a detector
"subharmonic" doppler would be the same.
David
David Brinicombe
North Devon, UK
Cogito cogito ergo cogito sum - Ambrose Bierce
"While a picture is worth a thousand words, a
sound is worth a thousand pictures." R. Murray Schafer via Bernie Krause.
------------------------------------------------------------------------
Yahoo! Groups Links
<*> To visit your group on the web, go to:
http://groups.yahoo.com/group/naturerecordists/
<*> Your email settings:
Digest Email | Traditional
<*> To change settings online go to:
http://groups.yahoo.com/group/naturerecordists/join
(Yahoo! ID required)
<*> To change settings via email:
<*> To unsubscribe from this group, send an email to:
<*> Your use of Yahoo! Groups is subject to:
http://docs.yahoo.com/info/terms/
------------------------------------------------------------------------
|