[CAUT] temperature and pitch

[David Ilvedson]

Have you blown a hair dryer across the strings of a piano.   Instantaneous lower pitch.   Many times I've been tuning and in the course of the tuning a door would be opened and cold air would come into the room and the pitch would go up.   Close the door and the pitch comes back down.   Tuning in a cross over area at  the Opera House directly below a vent which came on and the pitch went right on up...usually, it seems a couple of cents change...
I have no doubt in your church example the piano acclimated to the temperature...

David Ilvedson, RPT
Pacifica, CA  94044

----- Original message ----------------------------------------
From: "Elwood Doss" <edoss at utm.edu>
To: caut at ptg.org
Received: 12/11/2009 10:46:08 PM
Subject: Re: [CAUT] temperature and pitch


>Fred, et al.,
>It is my observation that it is the soundboard swelling and contracting with the 
>change of humidity that takes place with the change of temperature that causes the 
>pitch change.  As the soundboard swells, pressing up on the bridge, the strings 
>tighten and the pitch goes sharp.  The opposite takes place when the soundboard 
>contracts as the humidity level decreases in the air around it.  I should think wood 
>will respond to humidity/temp changes much more quickly that metal.  After all its the 
>humidity change with the rise/drop in temp that has such a profound effect on the 
>tuning of a piano.

>I would suggest that the change in metal, whether the plate or strings, with a 10° 
>temp change would be negligible, especially compared with the response of the 
>wood board.

>I work in the Mississippi valley and, as with other parts of the country, we have wide 
>swings of humidity.  In the buildings at UTM, there is a wide swing of temp and 
>humidity changes...from 30%/78° in the dead of winter with the heat on, and 
>80%/72° in the middle of summer with the air conditioning on.  In fact, my rule of 
>thumb is pianos like cool, rather than warm, interior temperatures.

>I recall tuning a Baldwin Studio upright at a small Methodist church in mid-December.  
>They turn the heat/air off during the week.  I asked them to have the heat set at 
>the same temperature that they worship which they did.  It was cool but 
>comfortable.  In mid-January I received a call from the mother of the pianist who 
>said the piano sounded horrible the Sunday before.  I made an appointment to meet 
>the pianist at the church.  As I entered he was playing and the piano sounded quite 
>in tune.  I noted the temperature was about what it was when I tuned it. As I 
>walked down the aisle, the pianist noticed my presence and exclaimed the piano 
>sounded great.  I asked him if this was the normal temperature and he said; then 
>added a caveat..."when the little old ladies come in they jack the thermostat way 
>up." 

>I tune the piano at the small church where I serve and more than once I've thought 
>to myself during the morning worship service that I need to get over here and tune 
>that piano, a Baldwin spinet.  During the evening service on the same day I'd think, 
>"the piano sounds great."  The difference...the heat/air was left on all day and the 
>piano had an opportunity to acclimate to the temp/humidity level which was the 
>same as when I tuned it.

>I feel these two examples are due to humidity changes that corresponds to the 
>temperature changes, rather than changes in the strings/plate.  Certainly the 
>strings and plate can be affected by temperature changes but I don't see that as a 
>primary reason we see such a change in tuning stability with a 5° to 10° change in 
>temperature.

>Joy!
>Elwood


>Elwood Doss, Jr., M.Mus.Ed., RPT
>Piano Technician/Technical Director
>Department of Music
>355 Clement Hall
>The University of Tennessee at Martin
>Martin, TN  38238
>731/881-1852
>FAX: 731/881-7415
>HOME: 731/587-5700
>-----Original Message-----
>From: caut-bounces at ptg.org [mailto:caut-bounces at ptg.org] On Behalf Of Fred 
>Sturm
>Sent: Friday, December 11, 2009 10:50 PM
>To: caut at ptg.org
>Subject: Re: [CAUT] temperature and pitch

>On Dec 11, 2009, at 4:07 PM, David Love wrote:

>> Can't comment on the amount of change per unit of temperature but  
>> the speed
>> with which it happens is fairly quick.  Started tuning a piano in a  
>> church
>> this morning with the temperature about 50 degrees at the start.   
>> Pitch was
>> about 2-3 cents sharp in the tenor section.  Tuning up from there by  
>> the
>> time I got to C5 (20 minutes or so) the temperature had risen to 70  
>> with the
>> heat on and a remeasure of the tenor section showed that the pitch  
>> was about
>> 2 cents flat--pretty uniformly.  Steinway D.  It does show that  
>> there are
>> clearly two aspects to pitch swings.  Temperature in which probably  
>> the
>> metal parts are affected, and humidity in which the wooden parts are
>> affected.


>What I think my example shows is the whole thing, strings and plate,  
>getting to the new temp and stabilizing there. Strings themselves move  
>pretty fast, especially if there is a bit of air movement with either  
>hot or cold air moving, or radiant heat (sun, stage lights). Some of  
>that is bound to be happening if the temp is rising in a room by 20  
>degrees over 20 minutes. That is one thing. But another thing is the  
>plate catching up with the temperature change, and possibly/probably  
>counteracting the initial pitch change a bit. I am assuming that  
>happened thoroughly overnight in my example, that plate and strings  
>had plenty of time to come to a stable new temp.
>	Not that this is some kind of definitive proof of anything. I just  
>had the opportunity to take data from an experiment that happened  
>without my needing to go to any effort. So I did so and documented it  
>"for the record." One Steinway A under the conditions I described did  
>what I described.
>Regards,
>Fred Sturm
>University of New Mexico
>fssturm at unm.edu