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