How does room acoustics affect tuning pitch?

[sidenius]

I will continue my series of questions concerning physical explanations of phenomena related to playing.
The question is based on on my experience with playing with my concert band in a gym with way too much reverb contra practicing at home in my living room with moderate reverb.
When I play with my concert band I have to push my main tuning slide about half an inch in compered to tuning at home in my living room to tune at 442.
What is the explanation of this phenomena?

Bertil

[windshieldbug]

Assuming the horn used is bell up, the ceiling in your living room is probably too low to permit the final wave node to form.

[humBell]

Does that mean the higher octave, having half the wavelength, might play in tune?

[Doug Elliott]

Try it and see. I'm not sure about the wavelengths in question, but an octave up might still be long enough to be affected by the ceiling.

[sidenius]

I assume that holding the horn horizontal and thereby having the bell playing into the open room would have an effect then?

[humBell]

Try it and see. I'm not sure about the wavelengths in question, but an octave up might still be long enough to be affected by the ceiling.

True. Nor do we know the height of the ceiling, nor the size of the room.

Something else to consider is room temperature, as that affects the speed o' sound, and if that changes, the same wavelength will resonate at a different frequency.

Is there a distinct difference in temperature between the two places?

[sidenius]

Try it and see. I'm not sure about the wavelengths in question, but an octave up might still be long enough to be affected by the ceiling.

True. Nor do we know the height of the ceiling, nor the size of the room.

Something else to consider is room temperature, as that affects the speed o' sound, and if that changes, the same wavelength will resonate at a different frequency.

Is there a distinct difference in temperature between the two places?

Yes there is. I would guess around 2 degrees Celsius.
Would that difference be big enough to make a significant difference in frequency?

My God - I wish I had payed more attention during the teaching hours in physics in primary school

As our famous danish philosopher, Soren Kirkegaard, once said: "Life is lived forwards but is understood backwards"

[humBell]

I wouldn't have thought it had that big an effect off hand, but it's possible.

Wikipedia article on speed of sound says it's roughly 0.6 meters/second faster per degree Celsius, and if the fundamental we're tuning is in 100 hz area, a centimeter longer wavelength would be needed to create the same frequency at 2 degrees, so no, at this back of the envelope analysis, it doesn't fully account for the difference, but i'm hand waving a lot of it, so it makes it more plausible.

A difference in humidity will also have an effect.

[Doug Elliott]

You need to consider (and test) how that temperature/speed difference affects the standing wave pitch in the horn, which may or may not be the same as the simple speed of sound in air. This is a similar question to the one about why two different players on identical equipment can be far apart in pitch. There's always more to it, no simple answer.

[Art Hovey]

A trumpet major in the Yale School of Music found this web page useful a couple of years ago:

http://www.galvanizedjazz.com/tuba/temperature.html

[Doug Elliott]

Nice detailed explanation.

[timothy42b]

That's a good description.

I think it's a little more complicated because a large horn is probably not all the same temperature - there is a gradual gradient as it warms up from where you touch it to the farthest point, and probably continuously cools at the edges if the room is cold, so the heat transfer to the air is probably different all the way along the length of the horn. I imagine there is conduction transfer from your hands and face to the horn, and convection transfer from blowing warm air through. If you're playing in an easy key there may even be valve tubing that hasn't been used for a while and has cooled, and then you press that valve and hit a cold spot. On a trombone some people use the F trigger infrequently, and that length of tubing might be at a totally different temperature that you don't notice until you engage it.

[TubaBeage]

I am interested in the same thing. I find the physical response in the body is very different depending on the setting. Doing much more practice during "these times" in a smaller room with a low ceiling can mess with your mind and things seem weird when you play outside or in a large barn.