From: firstname.lastname@example.org (N. Thornton)
Subject: Re: Bullshit wins v. science
Date: 7 Nov 2002 15:33:48 -0800
NNTP-Posting-Date: 7 Nov 2002 23:33:48 GMT
"Kevin Aylward" wrote in message news:...
> "N. Thornton" wrote in message
> > John Woodgate wrote in message
> > > about 'Bullshit wins v. science', on Wed, 6 Nov 2002:
re speaker distortion due to resonance.
> > > The resonances (one or more) of these systems do not involve any
> > > linearity at all, so no non-linearity distortion is produced.
> > It is still distortion, since the audio output does not accurately
> > follow the electrical input.
> Ho humm. No it isnt, as used by *any* *pro* ee in standard techical
> Yes, it could be argued that technically, distortion means any departure
> from v0(t)=C+ A.vin(t) equals. However, no one does this. *Unqualified*,
> distortion *means* non-linear distortion, i.e. THD, or IMD.
Distortion means, and I quote:
"The state of being distorted, or twisted out of shape or out of true
position; crookedness; perversion."
That is the _meaning_ of it.
The approach and industry practice you describe for measuring
distortion only measure certain types of distortion. They do not
Lets take a really clear example to illustrate. Lets say you delay
your audio signal by 1 second twice, and add the 3 signals: the
original one, the 1 sec delayed one, and the 2 sec delayed one. Any
speech put through that would be unintelligible. According to the
_definition_ of distortion, it is indeed distorted, badly distorted.
But if you measure the THD of this distorting process, it is zero.
I am perfectly aware that THD is the usual figure used, and am also
aware that it does not, contrary to popular ignorance, give a proper
picture of a speaker's distortion. A little thought will soon show why
they don't quote the _real_ distortion figure, it would be far worse,
and not as simple to test.