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From:    Cheryl Van Ornam  <congraziapublishing(at)ATTBI.COM>
Date:    Fri, 4 Oct 2002 06:24:39 -0400

----- Original Message ----- From: "Automatic digest processor" <LISTSERV(at)LISTS.MCGILL.CA> To: "Recipients of AUDITORY digests" <AUDITORY(at)LISTS.MCGILL.CA> Sent: Friday, October 04, 2002 12:00 AM Subject: AUDITORY Digest - 2 Oct 2002 to 3 Oct 2002 (#2002-165) > There are 3 messages totalling 129 lines in this issue. > > Topics of the day: > > 1. static spectral alterations > 2. Low frequency sound from PC (2) > > ---------------------------------------------------------------------- > > Date: Thu, 3 Oct 2002 11:42:36 -0500 > From: beauchamp james w <j-beauch(at)UX1.CSO.UIUC.EDU> > Subject: static spectral alterations > > Does anyone know of any peer-reviewed published papers on the > perceptual effect of static spectral alterations, such as might > occur due to room or speaker responses, on musical or other > types of sounds? The perceptual effect could be measured in > terms of sound source recognition, discrimination with respect > to original unaltered sources, or judgements of similarity to > the originals. > > The only paper I know of that touches on the subject is by > Arthur Benade (J. Audio Eng. Soc., Vol. 33, p. 218 (1985)). > His conclusion seemed to be that we can only recognise > musical instruments reliably in rooms that "average" sound > spectra when several notes are played. He played down the > importance of time-varation of spectra. > > Jim > > James W. Beauchamp > Professor Emeritus of Music and Electrical & Computer Engineering > University of Illinois at Urbana-Champaign > 2136 Music Bldg. MC-056 > 1114 W. Nevada, Urbana, IL 61801 USA > email: j-beauch(at)uiuc.edu > phone: +1-217-344-3307 (also: 217-244-1207 and 217-333-3691) > fax: +1-217-244-4585 > WWW: http://www.staff.uiuc.edu/~j-beauch > > ------------------------------ > > Date: Thu, 3 Oct 2002 18:34:53 -0700 > From: Jishnu Subedi <jishnusub(at)YAHOO.COM> > Subject: Low frequency sound from PC > > Dear List, > I am looking for suggestions to produce infra and low > frequency sound from 5 Hz and below to 100 Hz. Can I > use PC for this purpose? Does anyone have experience > which sound card, amplifier and loud speaker perform > best in this range? > > Thanks in advance! > > Jishnu > Graduate Student > Saitama University, Japan > > > __________________________________________________ > Do you Yahoo!? > New DSL Internet Access from SBC & Yahoo! > http://sbc.yahoo.com > > ------------------------------ > > Date: Fri, 4 Oct 2002 12:17:14 +1000 > From: Matt Flax <flatmax(at)IEEE.ORG> > Subject: Re: Low frequency sound from PC > > Hmmm this is an interesting one ! > > Most consumerables with pre-amp outputs (such as sound cards) have what > are called coupling capacitors at their outputs ... these capacitors are > designed to stop DC (0 Hz) signals from leaking between systems. Now > these coupling capacitors will probably also affect the 5Hz signals. > Now this may not be the case for sound cards - but I think it might be > ... perhaps someone else you know knows ? > > In order to overcome this you can either build your own bits ... try > amplitude modulating your signal up in frequency to say 100 Hz. Spit that > out the computer sound card... > Then build a filter which removes the modulation ... a demodulation > circuit for example. > Using that technique you can use your regular computer with modulated > signals and a demodulator/pre-amp. > > Another idea might be to create beats using 2 signals which are close to > each other in frequency. This option would require careful design and > probably require an custom analog mixer (with no coupling capacitors). > for example ... use the left channel (of your sound card) for signal 1 > and the right channel for signal 2 ... design the auditory signal so that > when added, beating occurs ... low pass filter that and wahlah ... low > frequency components restored .... > > There might be some off the shelf solutions as well ... but they would > cost alot more to make, unless your time is expensive ! > > Perhaps someone has already reported on this in the seismology world of > research ... where frequencies tend to be very low. > > Matt > > On Thu, Oct 03, 2002 at 06:34:53PM -0700, Jishnu Subedi wrote: > > Dear List, > > I am looking for suggestions to produce infra and low > > frequency sound from 5 Hz and below to 100 Hz. Can I > > use PC for this purpose? Does anyone have experience > > which sound card, amplifier and loud speaker perform > > best in this range? > > > > Thanks in advance! > > > > Jishnu > > Graduate Student > > Saitama University, Japan > > > > > > __________________________________________________ > > Do you Yahoo!? > > New DSL Internet Access from SBC & Yahoo! > > http://sbc.yahoo.com > > -- > http://mffm.darktech.org > > WSOLA TimeScale Audio Mod : http://mffmtimescale.sourceforge.net/ > FFTw C++ : http://mffmfftwrapper.sourceforge.net/ > Vector Bass : http://mffmvectorbass.sourceforge.net/ > Multimedia Time Code : http://mffmtimecode.sourceforge.net/ > > ------------------------------ > > End of AUDITORY Digest - 2 Oct 2002 to 3 Oct 2002 (#2002-165) > *************************************************************


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