# [CM] [Snd] Searching conditionally for starts and ends of phrases

**Ville Koskinen
**
j.v.o.koskinen@gmail.com

*Wed, 7 Mar 2007 16:19:33 +0200*

Hello,
I'm a starting user trying to customize Snd to edit spoken word audio.
I'd like to use Snd to find starts and ends of utterances. I can
calculate rms values at cursor, but I can't figure out how to
integrate this to the search.
My code is listed below. I suppose I've misunderstood something about
make-moving-average, but I don't know what (I also haven't found out
how to debug my code, so that's a problem too.
Any help appreciated!
Regards,
-Ville Koskinen
(define (rms position)
(let* ( (data
(channel->vct (max (- position 1024) 0) 1024)
)
(len
(vct-length data)
)
)
(sqrt (/ (dot-product data data) len))
)
)
(define (phrase-lookup)
(let* ( (search-for-sound
(if (< (rms (cursor)) .05) 1 0 )
)
(bufferlen
1024
)
(buffer
(make-moving-average bufferlen)
)
(lowthreshold
.00005
)
(highthreshold
.001
)
)
(lambda (y)
(let ((sum-of-squares (moving-average buffer (* y y)))
)
(if (= search-for-sound 1)
(> sum-of-squares highthreshold)
(< sum-of-squares lowthreshold)
)
)
)
)
)