Onsets (Al Bregman )

Subject: Onsets
From:    Al Bregman  <bregman(at)CCRMA.STANFORD.EDU>
Date:    Wed, 15 Sep 1993 13:08:49 -0700

Message from Bill Hartmann and answer by Al Bregman:

        Comment on onsets: You can get a good sense of discrete musical
notes from a continuous waveform (constant envelope, continuous
instantaneous phase angle) with frequency discontinuities.

I'VE NOTICED THAT MYSELF.  THESE FREQUENCY DISCONTIUITIES MIGHT TRANSLATE INTO
AMPLITUDE DISCONTINUITIES IN INDIVIDUAL FREQUENCY "CHANNELS".  THE SITUATION
WILL BE EVEN MORE COMPLEX WHEN THERE ARE ASYNCHRONOUS FREQUENCY OR AMPLITUDE
DISCONTINUITIES (MAYBE EVEN PHASE DISCONTINUITIES) IN DIFFERENT FREQUENCY
REGIONS.  STEVE MCADAMD COMMENT ABOUT THE APPLICABILITY OF OBJECT SEGREGATION
HEURISTICS IN VISION SEEMS TO BE RELEVANT.  IN AUDITION THE SYSTEM HAS TO
DECIDE WHETHER THE VARIOUS DISCONTINUITIES IN DIFFERENT FREQUENCY REGIONS ARE
THE BEGINNING (OR END) OF THE SAME EVENT.  INCIDENTALLY, I THINK THAT IT WOULD
BE BETTER TO USE THE NAME "EVENT" IN AUDITION, RATHER THAN IMPORTING THE NAME
"OBJECT" FROM VISION.  "EVENT" IS TO AUDITION WHAT 'OBJECT" IS TO VISION.

REGARDS,
 - AL