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From: prk@charm.UUCP (Paul Kolodner)
Newsgroups: net.audio
Subject: a new topic
Message-ID: <761@charm.UUCP>
Date: Mon, 23-Sep-85 21:50:12 EDT
Article-I.D.: charm.761
Posted: Mon Sep 23 21:50:12 1985
Date-Received: Fri, 27-Sep-85 07:41:30 EDT
Organization: Physics Research @ AT&T Bell Labs Murray Hill NJ
Lines: 28

I'm delighted that someone read my posting about my living room
enough to actually respond.  I have some new data.  This weekend,
I moved the speakers in front of the fireplace.  For those of you
who did not memorize my posting, this means that I now sit with my
back to a plaster wall.  The spaekers are in front of me, with a
wall of brick behind them, there is a plasterboard wall with floor-to-ceiling
curtains on my left and forty feet of empty space on my right.  How does it
sound?  TERRIBLE!  The high frequencies are gone, and there is a boominess
in the lows that is quite pronounced.  The sound is quite a bit more
constricted and closed-in.  The old arrangement sounded much more open
and airy.  My colleague, Dr. Femtoblatt, and I deduce that the high
frequencies are being sucked up by the space on the right and the drapes on
the left.  The brickwork behind may have had little effect - the speakers
don't radiate out the back anyway.  In this case, he suggested that the
acoustical properties of the wall behind the speakers are not important;
I have not noticed much difference with the drapes closed or open when
the speakers are returned to their original positon in front of said
drapes.
By the way, I have heard of Sonex acoustical pads.  They sound like a rip-off.
I have spent some time surveying the market for acoustical materials,
mostly in connection with noise control in my house.  There are several 
companies which make acoustically absorbing foam, and it can be quite a bit
cheaper than the amount mentioned.  There are also many other materials for
damping, isolation, and absorption on the market.  I wouldn't go slathering 
anything on my walls until I had a serious discussion with a technically 
competent acoustical engineer.  I happen to know just such a person, who 
works for a distributor of acoustical materials, and I will be glad to 
give his name and number to anyone who is interested enough to send me mail.