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hup_d_dup wrote: ↑Tue Mar 16, 2021 7:54 am I don't think people will do much playing in a vacuum, but it got me to thinking, what if you could play on Mars? So I asked my brother this question:

If you could play a brass instrument on Mars, how would the low atmospheric pressure affect the sound?

Here's the answer I got:

My guess would be that things would sound about an augmented fourth lower, not because of the low pressure but because of the components of the atmosphere.

The pitch of a brass instrument is given as:

frequency = speed of sound / wavelength

where the wavelength is related to the length of the instrument.

So if the speed of sound increases, the frequency would increase, and the opposite effect for a decrease in the speed.

The speed of sound depends principally on the temperature and composition of the gas (specifically on the heat capacity ratio), and depends very little on the pressure of the gas.

For Mars (mostly carbon dioxide), I find the speed of sound to be ~540 mph, compared to Earth with 760 mph. Since the speed on Mars is slower than on Earth, the pitch should go down.

With the speed on Mars being 40% slower, I calculate the number of half-steps, n, as:

2^(n/12) = 1.4

n=5.9, about 6 half-steps or an augmented fourth lower

I see from NASA’s site that the volume would also be greatly attenuated. So you may not be able to play as high on Mars, and it will seem like you’re playing with a tight mute.

However, I also asked this question to a physics professor at Princeton University, who also happens to play trumpet in a quintet I'm in, and I got a (somewhat) different answer:

Depends what aspect of the sound you mean. The simplest question perhaps is how would the pitch of the notes of the instrument change on Mars. The temporal frequency of a standing wave is proportional to the speed of sound, which is basically a function of the temperature and the mass of the molecules that make up the atmosphere. The speed of sound on Earth is 343m/s and on Mars it is ~240m/s. So the frequencies would all be lower by a factor of about 70% on Mars.

They agree that the pitch would be lower, but they disagree on the speed of sound on Mars.

Hup

Yorkboy wrote: ↑Mon Mar 15, 2021 7:42 pm

bloke wrote: ↑Mon Mar 15, 2021 6:56 pm

Yorkboy wrote: ↑Mon Mar 15, 2021 6:25 pm Not sure, but I’ve played plenty of tubas that suck like a vacuum

‘ finally played a Chinese knock-off of a “tornister” BB-flat.
I am the one who always says that most tubas can be played, if one can figure out what they “need“.… I haven’t figured out what this one needs, yet.