Timed experiments by default

[jonas.persson]

Do you have a practical example of application of such octave bands. The Wikipedia article is a bit short on references and, right now, I have no idea what it is good for.

Anything should be possible in phyphox, however, we likely need some guidance in this regard (also: linear or log scale…?). Until then, you need to/could zoom into the graphs of “Spectrum” and “History” to select a window of interest.

In Acoustics, measurements are done in different octaves so you get a fast picture of how the sound looks like frequency-wise. This is done in modern sound level meters (for example https://www.hbkworld.com/en/products/ins.../type-2245, https://www.nti-audio.com/en/products/so.../functions ). This is pretty standard procedure in sound level measurements, even if I do not remember a good book on the subject right now. 

There should be an acoustic department at a local university that has more information. It has been a long time since I worked with this, during my studies we had hardware filters for the different octaves, electronic/digital filters came later. I think the octave filters just take an interval around the octave centre [f_0/sqrt2, sqrt2 f_0] and sum all "intensities" in that interval. But I need to check that. I will try and write up an analysis in phyphox that will do that with the FFT data.

It was a long time ago I worked with this and I do not have my notes as I am on a sabbatical at another university.

[Jens Noriʇzsɔɥ]

Oh, something like this “Bandpass Amplitude”? Sebastian once did his magic…

[jonas.persson]

Oh, something like this “Bandpass Amplitude”? Sebastian once did his magic…

Yes, kind of. Instead of taking the average in a specific band, I need to add the amplitudes and use the sum. I can not figure out how to do that in a proper way. Defining 10 different bands (octaves) seems quite easy. The final step will be to adjust the amplitudes to the A-filter used in sound analysis, by multiplying with weights.

[Jens Noriʇzsɔɥ]

Have you had any progress on this? I do not yet understand the math behind it. What amplitudes need to be added? Are the A-filters done in Fourier Transform space (by multiplication)?

[jonas.persson]

Have you had any progress on this? I do not yet understand the math behind it. What amplitudes need to be added? Are the A-filters done in Fourier Transform space (by multiplication)?

I have managed to write an experiment that gives the SPL in different octaves. I need to tidy up the code before sharing.
But I need to check with a sound level meter that gives the different octave bands.
It worked when I did a test with a single tone.