+- phyphox Forums (https://phyphox.org/forums)
+-- Forum: Discussion (https://phyphox.org/forums/forumdisplay.php?fid=1)
+--- Forum: General (https://phyphox.org/forums/forumdisplay.php?fid=3)
+--- Thread: Fundamental frecuency of a wineglass (/showthread.php?tid=1485)
Fundamental frecuency of a wineglass - Aarón Ilizarbe - 12-17-2021
Good evening.
I have to measure the fundamental frequency of a wineglass from the Amplitude versus Time data. I would like to know if you could give me a suggestion or help. I have used "Audio Spectrum", and implemented an FFT code to find the fundamental frequency from this data, however, my results are not what I expected.
I don't know if I should really use "Audio Spectrum" or another function. I also think that I should measure the vibrations and thus find a graph of "Amplitude versus Time", in which case I am not sure how I should position my smartphone in relation to the wineglass.
I am looking forward to your response. Thanks in advance.
Oh! Thanks for the app, it's amazing!!
Aarón Ilizarbe.
RE: Fundamental frecuency of a wineglass - Jens Noriʇzsɔɥ - 12-17-2021
You are welcome Aarón
There are some options in order to measure the fundamental frequency. The “easiest” one is perhaps “Audio Autocorrelation” that shows the frequency (and musical note) right away. The autocorrelation graph gives you an indication of how “clean” the oscillation is.
You could also watch the “Audio Scope” and measure the length of the period, best over several periods. In the “Audio Spectrum” you could observe the different modes of the glass. You should consider to change the number of samples in the setting for a higher frequency resolution.
For some information on the different modes, I find https://sciencedemonstrations.fas.harvard.edu/presentations/shattering-wineglass rather instructive.
RE: Fundamental frecuency of a wineglass - solid - 12-17-2021
Hi Aarón,
you can try the last version of the corkscrewing experiment:
https://phyphox.org/forums/showthread.php?tid=776&pid=2650#pid2650
Do not pay attention to parameters, just knock the wineglass and look the resulting frequency... The experiment is specially adapted to short signals.
RE: Fundamental frecuency of a wineglass - Aarón Ilizarbe - 12-23-2021
Hi!
I want to thank both responses, they were very helpful to made my experiment and report for my laboratory project. I would not have made it without yout help, so I appreciate the creation of the Phyphox application.
I wish you all the best.
RE: Fundamental frecuency of a wineglass - solid - 12-23-2021
I tried myself the corkscrewing experiment using my wineglass (photo attached) and I got the following results:
mode....frequency,Hz f/f(2,0) "theoretical"
(2,0).....1300 1 1
(3,0) 2777 2.14 1.5² = 2.25
(4,0) 4934 3.78 2² = 4
(5,0) 7617 5.86 2.5² = 6.25
(6,0) 10711 8.24 3² = 9