[Audacity-nyquist] Echo Location

[paul b. <sni...@fa...>]

Hello, 

This plug-in examines what a bat does: Resonant filter, decay, and
downward FM sweep. Even though the input frequency is 300 hz., the peak
is three times greater. Therefore the center frequency of the filter is
set at three times the input. This strange result is probably due to the
fact that the zeroes of the Bessel function, second kind, order zero,
have a spacing of about three. With reverb, it sounds like anti
submarine sonar. Here is a 25k MP3. 

http://www.proviewlandscape.com/liss/das_boot.mp3

Frequencies do not travel at the same velocity. With a lightning strike,
at a distance, a rumble follows the initial crack. 
I don't know if dispersion is possible. See French, Waves and
Vibrations, page 230. --Paul Beach

;nyquist plug-in
;version 1
;type generate
;name "Bat..."
;action "Generating bat ..."
;control p "Pitch" real "Frequency" 300 1 8000
; 77 = owl,   333 = sonar 999 = sparrow
(reson
(mult (exp-dec 0 0.015 .2) ; decay .05
(fmosc (hz-to-step p ) (pwl 0 ( * p  2 ) .2)))

( * p  3 ) ( * p .25)  1 ) ; center and bandwidth 
; end of bat
-- 
  paul beach
  sni...@fa...