Project Science Of Electric Guitar: we did wave interference on paper, just estimating dots, then fired up an old school oscilloscope with two signal generators and nailed the same pattern by fluke picking two musical notes. Then we did some soldering, cos we're going to build a proof-of-concept amp. Best first-go soldering I've seen.
I'm learning so much from this. Classic "you don't understand it until you can explain it" stuff.
Today was a review of the work of John Deacon (electrical engineering and the legendary "Deacy Amp"), and Brian May's work on spectroscopy, and the similarities between sound waves, electrical waveforms, and light waves.
Then we started our amp: jack connection wires and input capacitor soldered into place. Next week is the transistor...
I'm surprised to hear beats, given that I don't think I've seen destructive interference of nearby peaks in spectrum ever. Where does this difference come from?
@robryk It's nanometer wavelengths converted to Hz sine waves, so not strictly comparable, I just liked the way the numbers matched up. But yeah, the beat frequencies were a lovely surprise, mostly down to the main ~100s nm optical range being tight compared to the 20-20k range of human hearing.
@_thegeoff wait, but didn't this map frequencies to (some multiple) of their inverses?
@robryk Light wavelengths in nm to sound freq in Hz, simply because the numbers are both nicely within the respective human ranges.
So yeah, going backwards, freq to 1/freq with a few orders of magnitude translation between the speed of light and sound.
Sadly, this transformation changes everything far enough that IMO beats do not map to much of anything interesting in the original configuration.
To see that this mapping changes things very significantly, notice that a base frequency and a few harmonics map to something that has no base frequency, but is rather a mixture of a few unrelated frequencies and their common harmonic. This IMO means that interesting relationships between frequencies are not preserved.
If we talk about beats specifically, then the frequency difference "on the audio side" here is a nonlinear function of the frequency difference "on the light side", so even if we were to consider some hypothetical creatures that have very short averaging timescales in vision (so that they can perceive beats at differences e.g. as small as a few MHz[1]), this map to something weird on the audio side (the minimal frequency difference will not be constant over the range we're considering).
[1] This does not necessitate them having awareness of such short time intervals btw.: a human, with help of an FM radio receiver, can do something equivalent to detecting beats with frequency differences of small hundreds of kHz. A creature could have sense organs that can do something similar without their conscious processing having to run at higher speeds.
(BTW. This sounds like a potential worldbuilding idea for a short story.)
