Singing Glasses: Tuning to a Certain Frequency

[Follik]

Hey everyone,

I have a question, about singing wine glasses that I just can't seem to find the answer too while searching through different web-pages that google gave me.

I'm doing a year end project for my high school physics course, and I decided to do mine on these singing wine glasses, and resonance. I'm thinking I will have 12 cups (1 octave) and tune them using this note/frequency chart I have, and then explain how more or less water effects the changing pitch, then end with a little demostration of a song.

My problem/question is how exactly would I be able to tune the cups? I know I can just add/remove water and tune by ear, but I am looking for a certain equation (if there is one) to find how much water I need in the glass to preduce a certain pitch.

Any suggestions, short tutorial and advice is much appreciate as I am currently stuck with a few weeks left. An example of how to tune to, say, D#1 which frequency is 38.9hz would help a lot so I can see the steps... :)

Thanks a lot!

 

[Follik]

More information:

I have this 'finding frequency' equation: Wavelength = v(speed of sound)/frequency

I plug everything in, for example:

Wavelength = (340m/s)/38.9hz
= 8.74

That's the answer I get... so I am not sure if that takes into account the length of my glass, or if I am suppose to fill it 8.74 or leave air gap of 8.74. :s

 

[Ben Niehoff]

Read about how open-ended wind instruments work.

Also, the shape of the wine glass might affect the tuning.