The Cyber-Spy.Com Usenet Archive Feeds Directly
From The Open And Publicly Available Newsgroup
This Group And Thousands Of Others Are Available
On Most IS NNTP News Servers On Port 119.
Cyber-Spy.Com Is NOT Responsible For Any Topic,
Opinions Or Content Posted To This Or Any Other
Newsgroup. This Web Archive Of The Newsgroup And
Posts Are For Informational Purposes Only.
From: "Phil Allison"
References: <96dU9.21919$jM5.firstname.lastname@example.org> <email@example.com>
Subject: Re: Acoustic Feedback reduction
X-Newsreader: Microsoft Outlook Express 5.50.4522.1200
Date: Mon, 13 Jan 2003 11:01:22 +1100
NNTP-Posting-Date: Mon, 13 Jan 2003 10:50:54 EST
Organization: Telstra BigPond Internet Services (http://www.bigpond.com)
"Don Pearce" wrote in message
> On Mon, 13 Jan 2003 00:20:58 +1100, "Phil Allison"
> >"Don Pearce" wrote in message
> >> On Sun, 12 Jan 2003 23:33:10 +1100, "Phil Allison"
> >> wrote:
> >> > The number of persons I have had to FIGHT with over this
> >> >terminology issue is appalling - they all think that frequency and
> >> >mean the same thing.
> >> >
> >> > Pitch shifting is of course of NO use in feedback supression.
> >> >
> >> >
> >> > ................... Phil
> >> First - I am not looking for a fight.
> > ** But I am gonna give you one Mr Expert.
> >> But - the only difference between pitch shifting and frequency
> >> shifting is that in pitch shifting, each frequency is shifted by a
> >> certain percentage of itself, while in frequency shifting each
> >> frequency is shifted by a given number of Hz.
> > ** THAT is one HELL of a difference.
> Not in the context - both do indeed necessitate a frequency shift.
** Bull, it is massive in context. Stick to RF Don. One cannot use
pitch shift in a PA system to reduce feedback.
> >> The two are different in one important regard - in pitch shifting the
> >> harmonic relationships are preserved and the result remains musical.
> >> In frequency shifting this does not happen, and if the shift is
> >> carried too far, the result is very unmusical.
> > ** A few Hz upshift has no detectable impact on most ears.
> Depends on the frequency. At low frequency a few Hz shift could
> represent a semitone - decidedly detectable.
** Not on music programme. Only on tones and only if quickly A-B ed.
> Shame you decided to start out by being rude. Especially as in the
> rest of the post you haven't really contradicted anything I said -
> merely expanded on it.
** I contradicted the whole stupid lot.
There are a few areas of specific error in your
> last section, though. The main one is your confusion between
> reverberation and standing waves. They are not the same thing and a
> space can be highly reverberant with no standing waves whatever.
** Complete bullshit. What planet do you come from ?
You have clearly never seen the *slow* sweep response of an
auditorium - it is full of sharp peaks and dips. What do you suspect
causes them? Men from Mars ?
Ever done a slow response sweep of a digital reverb unit - guess what -
same peaks and dips - guess why ???
And> of course your arbitrary limits of 4 to 20Hz have no meaning.
** Only to a moronic jerk like you Don. These are the lowest frequency
standing waves that can be supported in auditoria and rooms where a PA might
be used. All other standing waves are derived from these by integer
> And of course there are resonant structures that affect howl frequency
> besides the room.
** The room is the one with the really high Q resonances - several
thousand of them with Qs in the thousands at high frequencies.
The loudspeakers and microphones are a mass of
> resonant peaks themselves. Being able to shift the feedback tone off
> the top of one of these peaks can give you an extra few dBs of margin
> in the onset of feedback.
** No, the peaks in them are too broad. It makes practically no
difference - plus they are not evenly spaced by a fixed number of Hz like in
Go Back To The Cyber-Spy.Com
Usenet Web Archive Index Of
The sci.electronics.design Newsgroup