Measurement of the resonance curve (Acoustics)

[paul.davies@york.ac.uk]

In the phyphox version 1.1.8-beta2 the tone generator is repared !
In the upper part of the figure the acoustic spectrum of a PVC tube is obtained by FFT transformation of the response to the white noise (time of measurements 100 s). In the lower panel of the figure the same spectrum is obtained by the frequency sweep (time of measurements 2500 s).

This is superb, I have had some trouble with the white noise generator. It seems to have some artifacts in the spectrum and responds differently with different phones. But a little bit of playing and I found that 'crinkling' a sheet of paper in place of the phone generated noise produces an excellent spectrum. I've attached a picture below. The tube was the cardboard inner from some Christmas wrapping paper (about 0.7m long and .03m diameter). As you can see below the spectrum is lovely and after only a few runs. 

I plan to have my students try this at home and we will measure the speed of sound. 

Thanks again, Paul