pete@valid.UUCP (Pete Zakel) (01/17/86)
The latest Science News (January 4, 1986, Vol. 129, No. 1) has an article
"Acoustic Residues" which describes a new type of acoustic paneling based
on quadratic-residue sequences. The example in the article uses the prime
number 17 for designing a reflection phase grating that gives proper
diffusion for making music sound better in poor listening environments.
Basically, the panels consist of a sequence of "wells" whose depth
corresponds to the remainder of the well number squared divided by the
prime number used. In the example the number 17 is used which gives depths
of 1, 4, 9, 16, 8, 2, 15, 13, 13, 15, 2, 8, 16, 9, 4, 1, ...
The gratings can be used around speakers to minimize early reflections,
behind performers during recording sessions, on ceilings to "expand" the size
of the room, etc., etc. I won't try to repeat the entire article here, but
I'll mention that panels are being manufactured by RPG Diffusor Systems, Inc.
in Largo, MD. The scientist who pioneered the ideas is Manfred R. Schroeder
of the Drittes Physikalisches Institut at the University of Goettingen in
West Germany. He's also associated with AT&T Bell Labs in Murray Hill, NJ.
The title of his recent address to the Acoustical Society of America was:
"The unreasonable effectiveness of number theory in acoustics."
-Pete Zakel (..!{hplabs,amd,pyramid,ihnp4}!pesnta!valid!pete)kort@hounx.UUCP (B.KORT) (01/19/86)
Gee, all those pure mathematicians who were holding out for number theory as one of the few branches of mathematics without any practical application are going to be mighty upset that some damn engineer from Bell Labs has gone and found a practical application for it. Oh, Benoit--have you anything new we can play with that the engineers have't got their hands on? Benoit? Hello? (Hmmm. Something wrong with this connection.) --Barry Kort
weemba@brahms.BERKELEY.EDU (Matthew P. Wiener) (01/21/86)
In article <522@hounx.UUCP> kort@hounx.UUCP (B.KORT) writes: >Gee, all those pure mathematicians who were holding out >for number theory as one of the few branches of mathematics >without any practical application are going to be mighty >upset that some damn engineer from Bell Labs has gone and >found a practical application for it. I'm curious where people get the idea that number theory has been without applications all this time. They go back at least 40 years, probably more. ucbvax!brahms!weemba Matthew P Wiener/UCB Math Dept/Berkeley CA 94720