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Re: Perception of rise/fall times

One corollary observation (I owe it to my esteemed colleagues Eric Prame
and Bob Efron):

Slow (~1 to ~5 Hz) sinusoidal amplitude modulation produces one perceptual
event per cycle (coinciding with the peak or the onsetof the positive
ramp). Slow sinusoidal frequency modulation produces two.


At 03:31 PM 5/10/01 -0400, Dennis P. Phillips, Ph.D. wrote:
Hi Everyone:

I'd like to thank all who responded to my recent question about asymmetries
in the perceptual effects of rise and fall times.  The responses were
diverse, thoughtful, informative, and often pointed me to references which
I had not previously found.  This has been very helpful indeed. Again, many

For folks who are interested, a "potted" summary would go something like
this.  Sounds with fast onsets and slow decays are judged as louder than
their time-reversed analogs.  Sinusoids with exponential onsets (ramped
sinusoids) have a more tonal quality, and a less hollow, percussive one,
than their time-reversed counterparts (damped sinusoids).  Normal listeners
are more sensitive to switching transients at the onset of a tone than to
those at its offset.  Thresholds for amplitude decrement detection are
comparable to those for increment detection if the decrement is not too
short in duration.  Rise times (plucks and bows) are not perceived
categorically.  In general, these findings point to the perceptual
importance of stimulus onsets (or increments).  Below are a few of the

Pierre Divenyi, Ph.D.      Speech and Hearing Research (151)
                                     V.A. Medical Center, Martinez, CA
94553, USA
Phone: (925) 370-6745
Fax:     (925) 228-5738
E-mail :                       pdivenyi@marva4.ebire.org