[pianotech] Louder, after tuning? (simplified)

[Tom Rhea, Jr.]

The strength of the sound a string generates is in its amplitude (the
distance from peak-to-peak as measured with an oscilloscope).  Two or three
wires tuned to exactly the same frequency will, being in phase, reinforce
each other and sound louder to the ear and on an oscilloscope.  If one
string in a bichord is slightly off tune to the other then a heterodyne
effect is created where the off-tuned string actually detracts from the
amplitude of the combined string combination and can be heard as a "beating"
sound.  The beating can be hardly noticeable (i.e., very slow) to rapid.
The beats are a result of the two string frequencies combining in a
non-linear medium (the strings themselves) and creating a difference
frequency (the beats) which is a difference of the two individual string
frequencies.  This difference frequency actually acts as an out-of-phase
component and reduces the combined amplitude of the two individual strings,
thus making the overall amplitude less.  The effect is even more pronounced
on a trichord.

In actuality, though, tuning a bichord or trichord will result in an overall
increase in amplitude but it will be a bit less than if the two or three
strings were perfectly in tune (in phase).

Tom

-----Original Message-----
From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of Piano Boutique
Sent: Thursday, December 30, 2010 4:30 PM
To: pianotech at ptg.org
Subject: Re: [pianotech] Louder, after tuning? (simplified)

Keith,

I guess I should have said that the strings transfer to the sound board vie 
the bridge, but I am a simple kind of guy.

William



----- Original Message ----- 
From: "Mr. Mac's" <tune-repair at allegiance.tv>
To: <pianotech at ptg.org>
Sent: Thursday, December 30, 2010 3:03 PM
Subject: Re: [pianotech] Louder, after tuning? (simplified)



On Dec 30, 2010, at 1:34 PM, Piano Boutique wrote:

> keith; It is my understanding that two strings in tune are lowder. They 
> move together and show louder patterns on a DB meater. By working 
> together; they move more air.; Two strings out of tune have more disanence

> and are harsher on the ear drum; which would confuse the human; but shows 
> not as lowd on a meater.; This is just what I have ben told and i give it 
> you in good faith.; William Benjamin; PTG RPT


Very interesting information you have presented, William.

Perceptions are so individual, yet, apparently not so on a measuring device 
as you have indicated.

Thank you so much for sharing as you have done.

Keith=