🚀 go-pugleaf

Subject:  Decibel meter needed?! for HS science project
  
I am a volunteer advisor helping high school students prepare projects for science fair competition.  Not too infrequently, projects evolve beyond the resources in my basement and my expertise.  A current project involving sound absorption by "acoustical 

tiles" --homemade using fiber reinforced recycled newspapers-- has done both.  The main objective of the project is to determine the value of recycled newspapers for acoustical tiles versus their value for use as fuel or for paper products.  Acoustics is 

not the prime thrust of the project.
 
Problem:  My student needs a simple means to evaluate the sound absorbing effectiveness of her recycled-newspaper acoustical tile.   (Relative to other tiles and materials)
 
I want her to start out very simply.  If interested, she can pursue more sophisticated measurements and equipment in a continuation project next year, she is a ninth grader.  For openers, I have recommended playing taped sounds...not a single frequency bu

t close to it ...at low and high frequencies.  The source could be a Sony Walkman or the like with the original tone coming from a musical instrument or music room sound generator.  A detailed frequency / absorption curve would not be measured, only sever

al points.  Measurements would be done in a carpet-lined enclosure (small), using a microphone pick-up.
 

Question / Help / Equipment Needed:  What can we use to measure the output, or change in output?  Any references to simple approaches would help.
 
Components must be readily available in the average home, or very, very cheap (preferably free).  I have assumed a decibel meter is what we need, a Heathkit or the like... to date myself, our school doesn't have one.  I have a microphone and an old stand-

alone amplifier, I don't think the preamp is reliable.  What is needed up-front so I can use a multimeter?...mine has a dB scale.  Are the simple meters on tape recorders, that indicate sound level, dB or linear?

Thanks for any help or suggestions you might have.

PS If anyone is interested in our extracurricular science enrichment program for motivated high school students, I have just submitted a 1200 word description for publication in the Materials Research Society's MRS Bulletin.  A copy can be sent by email o



-- 
hbstrock@world.std.com			phone/fax 508/829-9610
Harold B. Strock, PhD
Strock Technology Associates, Inc.	Independent Licensing Executive
40 Driftwood DR				Consultant in advanced materials