I wrote a response to kirk but took so long he's probably gone.

Anyway, here are a few links, of varying quality, that appear to be
on about the same thing. The first seems OK, and links through to
Arny at some point, so it must be true.

http://www.silcom.com/~aludwig/Phase_audibility.htm

http://www.secondbeat.com/html/artic...ue6/phase.html

http://www.websmith.co.za/vt/amp.html (centre paragraph...a
marketing view)

For my own amusement, I drew a graph of my amps' frequency response
showing relative distance v frequency on a linear scale.

If my ears could interpret the result, then a (very) bass note
sliding down an octave from 80Hz, taking 1/10th of a second to do
so, would rush at me at 136mph, leaping several yards. Next octave
up is a very small fraction of that, then it is constant up to as
high as I can measure.

Anyway, I understand that we physically respond to the sound of a
leaping tiger before we even become aware of the pitch of its growl.
Perhaps my bass is scaring people away but, because they don't
attribute the scary feeling to the sound, they think its me that's
scary?

However. Without a fixed frequency reference, I guess it's
interpreted as part of the frequency shift, and it just changes the
shape of the slide a bit.

cheers, Ian

"Ian Iveson" wrote in message
...
I wrote a response to kirk but took so long he's probably gone.

Hi Ian . . .

I don't have a computer at home, and my office-time is rather spotty, so
please forgive my on-again/off-again presence here on RAT . . .

Anyway, one of my recent light-reading texts has been 'Acoustic
Communication', second edition, by Barry Truax . . . I'm only about a third
of the way through it right now but it is excellent . . . highly recommended
.. . . it searches and proposes links and mediation between disciplines of
acoustics, psychoacoustics, linguistics, electroacoustics, and of course,
communication.

I re-read your previous posts regarding phase distortion, and I think that
there is a problem with the concept of thinking that one's awareness of
phase will translate to awareness of delay, and therefore awareness of
distance or motion in space. I would guess that the brain locates some
sounds as distant and some as near based on the recognition of the patterns
of environmental reflection and propegation through the air . . . we
actually wouldn't use aural propegation clues to determine how fast the
tiger is moving at us, rather, just that its DAMN CLOSE, it's somewhere OVER
THERE and we'd better RUN THE OTHER WAY. In this instance, the ability of
the brain to not just determine distance and direction, but the association
of the sound of the tiger with the memories of what a tiger is, or at least
what types of things make loud roaring sounds, would be the most important
aspects of survival based on these aural cues.

It seems that a certain duration must be present for a sound to be perceived
as having pitch . . . a single-cycle tone burst at 20Hz and and a
single-cycle tone burst at 1,000Hz both sound like clicks . . . and the
duration of a single-cycle tone burst at 20Hz is probably greater than the
amount of delay associated with the phase distortion in your amplifier.
Thus, I would also guess that what we are looking for in terms of audible
effects of phase distortion in the quantities produced by audio equipment
would be ultimately represented by changes in timbre (stereo image aside). .
.. and it would be difficult to quantify without a "blameless" amplifier to
use as a control group. Probably the more indicative analysis graph would
be a before/after spectrograph, rather than a Bode plot. I think that the
sound files at the beginning of the "silcom.com" article probably have more
effect on the ADSR envelope of the sound than one would expect in an
amplifier.

Anyway, it's time to get out of here . . . it is the weekend, after all.

Best regards,

Kirk