[78-L] Acoustic recording

[Kevin P. Mostyn]

I forwarded the original posting to Clark Johnsen, who is an old friend.
Here is his reply.
 
Kevin Mostyn
 
 ---------- Forwarded message ----------
From: Clark Johnsen <clarkjohnsen at gmail.com>
Date: Sun, Jul 10, 2011 at 12:08 PM
Subject: Re: FW: [78-L] Acoustic recording

The correspondence below was forwarded to me. Mike Biel has it mostly right,
except the spelling of my last name and the title of my book, "The Wood
Effect". (Full title The Wood Effect: Unaccounted Contributor to Error and
Confusion in Acoustics and Audio) Also, one prefers the word "polarity" as
opposed to "phase", because this is an in-or-out bipolar condition.

A few copies of the book are still available at $20 plus pp. Highly
recommended. Here's an article I wrote about it:
http://www.positive-feedback.com/Issue1/cjwoodeffect.htm

clark





-----Original Message-----
From: 78-l-bounces at klickitat.78online.com
[mailto:78-l-bounces at klickitat.78online.com] On Behalf Of Michael Biel
Sent: Saturday, July 02, 2011 11:59 AM
To: 78-L Mail List
Subject: Re: [78-L] Acoustic recording

From: "DanKj" <MLK402 at verizon.net>
> Many of my instrumental Pathe records sound oddly "backwards"
> (Sergeant Legget cornet solos, especially; is this what we're talking
> about? (I can only describe it as MMahh MMahh MMaah as opposed to Wahh
> Wahh Wahh)


Pathe records are all dubs, so the polarity of the absolute phase is not
necessarily consistent.  What you are hearing is what Clark Johnson has
called "The Wooden Effect" which is the name of a little book he wrote about
it.  Some people are more sensitive to it than others, although he says that
it is a major cause of listening fatigue among people who can't quite place
what is happening.  (I am one of those who do not consciously notice it.)
Most sounds will have a positive pressure at the start of notes, but if the
absolute phase of the sound is reversed, the loudspeaker or the diaphragm
will start the notes with a negative pressure with the cone or diaphragm
moving backwards instead of forwards.  If you reverse the speaker
connections it would solve it, and it is something that those who are
sensitive to the effect would check for each record.  Clark gives examples
of overdubbed recordings where the orchestra and the vocalist are at
different absolute phasing, leaving the listener in a quandary as to which
way to set it.

Let me make this clear that I am not talking about relative phase between
two stereo channels.  The two speakers must be in the same phase as each
other.  This is matching the phasing of all of the speakers with the
original sound.


Mike Biel  mbiel at mbiel.com


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