10-05-2021, 12:03 AM
(This post was last modified: 10-05-2021, 12:50 AM by Erik Josefsson.)
(10-04-2021, 09:43 AM)Jens Noritzsch Wrote: Dear Eric,
there is an alternative with just one smartphone and earbuds suggested by the NPL, https://www.npl.co.uk/measurement-at-hom...ilet-rolls, and utilised by Physics in Advent on December 3, 2020, see https://youtu.be/wUAFem8eEKI and https://youtu.be/-8MO0Uacn5w
Would this work for you?
Best regards,
Jens
That's a very nice setup! Thank you!! //Erik
(10-04-2021, 05:43 PM)solid Wrote: Hello
Thank you for the references, Jens.
I tried the toilet paper NPL experiment and I found it not very precise.. I got the wavelength 10 cm and the sound speed 400 m/s for the frequency of 4 kHz.
Then I took one smartphone with phyphox sound generator at 4 kHz. I put its headphones 50 cm apart and took another smartphone with audio amplitude of phyphox and moved it slowly at a distance of 1 m over about 1 m. I tried to keep a constant speed of the motion. The result is here, could be better... Probably some things around including me interfere also.
Best
Mikhail
Well, one pair of headphones is actually two speakers, so we did more or less the same experiment :-) I was also trying to move the phyphoxphone/Audio Amplitude with constant speed, but your result is much better than mine!
Thank you solid.
//Erik
Further to solid's response in this thread, has anyone seen device-specific calibration data for the Audio Amplitude experiment? My Galaxy III has a "Reference SPL" default setting 60 dB (not sure what the "offset" below does?), but maybe that's a default value set for all phones?
Anyway, I will try again tomorrow with a larger tube than stacked toilet paper rolls. Turns out a transparent plastic curtain box from IKEA (FRIDANS) works perfectly as running tracks for their toy cars (LILLABO). Maybe I can pull a phyphoxphone on a string through it and get the Audio Amplitude to clearly detect sound wave interference peaks.
//Erik