[pianotech] FW: RE: New Ask Physicist question

[Paul McCloud]

I'm sure this has been mentioned, but I'm coming late into this discussion
(my ISP blocked a few days of posts).  It is a question of efficiency.  Is
the energy of the vibrating string amplified?  No.  There is no energy being
added, so there is no amplification.  The soundboard assembly is passive.
There is no electrical current or other power source from which energy is
being supplied to the system.  But, there is the question of the efficiency
of the coupling of the vibration to the air.  The surface area is increased,
so the vibration is moving a lot more air molecules.  The sound pressure
level is higher because of this.  The coupling of the vibration to the sound
pressure is more efficient, so we hear it as being "louder".  If the
definition of "amplify" is to make a sound louder, then yes, it  does
"amplify".  But, in a strict sense, there is no added energy, so there is no
amplification. 
Just my $.02.

Paul McCloud
San Diego (where the laws of physics still apply)

-----Original Message-----
From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of Stéphane Collin
Sent: Monday, May 18, 2009 9:05 AM
To: pianotech at ptg.org
Subject: Re: [pianotech] FW: RE: New Ask Physicist question

Hi Del, Hi David.

I find it nice every now and then to refresh my forever imperfect knowledge
of any matter.
So, my understanding about this matter (subject to change without notice) is
like this :

- If we talk kinetic energy, the one input into the strings by mean of the
hammer strike is transmitted to the soundboard in a way ruled by the
impedances of both the strings and the soundboard, knowing that some of the
energy is wasted in heat because of friction issues everywhere.

- If we talk acoustic pressure level, the one caused by the strings is very
low, due to small surface of the strings and huge short circuit effect of
the air surrounding them when they move.  The one caused by the driven
soundboard is much higher, even considering the reduction of kinetic energy
after its transfer from the strings to the soundboard, because of its large
surface.  So, one can say that the soundboard is an acoustic pressure
amplifier of its driving strings.  Not ?

This comment only intended to raise more interesting comments.

Best regards.

Stéphane Collin.




-----Original Message-----
From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of Delwin D Fandrich
Sent: dimanche 17 mai 2009 22:52
To: 'David Ilvedson'; pianotech at ptg.org
Subject: Re: [pianotech] FW: RE: New Ask Physicist question


A good example of a (probably) well educated person expressing an opinion on
a
subject which he/she knows nothing about.

ddf 

| -----Original Message-----
| From: pianotech-bounces at ptg.org 
| [mailto:pianotech-bounces at ptg.org] On Behalf Of David Ilvedson
| Sent: May 16, 2009 6:49 PM
| To: pianotech at ptg.org; caut at ptg.org
| Subject: [pianotech] FW: RE: New Ask Physicist question
| 
| List...
| 
| Here is the reply I received from "The Physicist"...whoever 
| that is... '-]
| 
| David Ilvedson
| 
| ----- This is a forwarded message 
| ----------------------------------------
| From: "the physicist" <the_physicist at askthephysicist.com>
| To: ilvey at sbcglobal.net
| Received: 5/16/2009 1:17:39 PM
| Subject: RE: New Ask Physicist question
| 
| 
| A transducer normally refers to something which converts 
| mechanical vibrations into electrical vibrations. I would 
| call the instruments you refer to as amplifying the sound. 
| There is more to it than that since they also filter various 
| components, that is they amplify some frequencies better than others.
| 
| The Physicist
| @AskThePhysicist.com
| 
| -----Original Message-----
| From: ilvey at sbcglobal.net [mailto:ilvey at sbcglobal.net]
| Sent: Tuesday, May 12, 2009 12:45 PM
| To: the_physicist at askthephysicist.com
| Subject: New Ask Physicist question
| 
| user_email -- ilvey at sbcglobal.net
| question -- Is an acoustic piano soundboard an amplifier or a 
| transducer?
| The same would be for any musical instrument 
| soundboard...guitar, violin....
| 
| 





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