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----- Original Message -----
From: "Automatic digest processor" <LISTSERV@LISTS.MCGILL.CA>
To: "Recipients of AUDITORY digests" <AUDITORY@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@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.
> 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: email@example.com
> 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@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!
> Graduate Student
> Saitama University, Japan
> Do you Yahoo!?
> New DSL Internet Access from SBC & Yahoo!
> Date: Fri, 4 Oct 2002 12:17:14 +1000
> From: Matt Flax <flatmax@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.
> 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
> 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)