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Re: Fw: sursound: speaker phones

The answer is binaural and monaural decolorization, the first wavefront
determines the timbre. With recordings the correct binaural and monaural
cues are missing and thus its sounds hollow/colored. A ref. for the binaural

P. M. Zurek, "Measurements of Binaural Echo Suppression", J. Acoust. Soc.
Am., vol. 66, pp. 1750-1757 (1979 Dec.).

John Beerends
KPN Research

-----Original Message-----
From: James W. Beauchamp [mailto:j-beauch@UX1.CSO.UIUC.EDU]
Sent: Wednesday, October 25, 2000 20:44
Subject: Re: Fw: sursound: speaker phones

While we're on the subject of sound localization, can someone explain
why speaker phones always sound like you're "talking through a tube" to
the person on the other end of the line? I'm radiating a sound which
is picked up by a diaphragm on a table and then directly transmitted
to someone's ear via a small speaker. How is this substantially
different from my talking to a hole in the table with someone's ear
directly underneath?

Here is a related problem: Suppose I wish to record someone talking in
the front of the room, and I am in the back of the room. When I am
actually there listening, the speech is as clear as a bell; I ignore
all environmental sounds and echoes. To (roughly) simulate the pressures
at the ears, I take the headphone of my Walkman, put it on, and use it
as a stereo microphone. Later, when I play it back through the headphones,
the basic sound is there, but now the echos and environmental sounds swamp
out the speaker, who is rendered barely audible. Does using really good
mics help? (Cheap actual mics don't seem to improve the situation.)

If we understand what the problem is, how do we correct for it?  E. g.,
why aren't there better speaker phones? (Maybe there are for a price.)

I realize that this problem is being worked on in the context of hearing
aids -- my neighbor has to take his off in order to hear a conversation
when there's more than 1 other person talking -- and in tele-conferencing

Jim Beauchamp
Univ. of Ill. U-C