(definstrument squelchy (beg dur file skip squelch)
  (let* ((skipsamp (floor (* (or skip 0) (sound-srate file))))
	 (fdA (open-input file :channel 0 :start skipsamp :verbose t))
	 (two-chans (and (= (sound-chans file) 2) (= (mus-channels *output*) 2)))
	 (fdB (and two-chans (open-input file :channel 1 :start skipsamp :verbose t)))
	 (rdA (make-readin fdA))
	 (rdB (make-readin fdB))
         (st (floor (* *srate* beg)))
         (nd (+ st (floor (* *srate* dur))))
         )
    (run
     (loop for i from st below nd do
	   (let ((outvalA (readin rdA))
		 (outvalB (readin rdB)))
	     (if (< (* -1 squelch) outvalA squelch)
	       (setf outvalA 0))
	     (if (< (* -1 squelch) outvalB squelch)
	       (setf outvalB 0))
	     (outa i outvalA)
	     (if two-chans (outb i outvalB)))
	   ))
    (close-input fdA)
    (if two-chans (close-input fdB))))
#|
(compile-file "squelchy.ins")
(load "squelchy.cmucl")

(with-sound (:srate 44100 :channels 2 :statistics t :scaled-to .5 :output "/zap/squelchy.snd") 
  (squelchy 0 10 "/home/bsack/sounds/apresafter.wav" 48 .005))
|#