I have a mild amount of experience in engine theory and tuning... if it shows. I used to do the calculations for intake resonance to setup velocity stacks on race bikes as well as some porting and other machine work.
If you ever wondered why Lamborghini and Ferrari engine intakes sound like musical instruments at high RPM - intake harmonics tuning at work.
The real brain bender is when you get into the reality of those harmonic waves, and how they are applied to engine tuning, some of the old "wives tales" somewhat go out the window. The "longer intakes make more power at lower RPM" for example, is both true and untrue.
A longer intake at the same harmonic wave position does, but if you tune for a higher harmonic resonance at a higher resonance strength (lower position) then it will still benefit higher RPM power, and the effect is greater.
This is due to how harmonic waves behave. The time it takes for the wave to be sent from the node, hit the anode, and return happens over a given distance. If it occours in one pulse, it is known as a first harmonic. The issue is, first harmonics require a very long distance to travel, usually several meters, which is a bit unreasonable to fit in an engine bay, so engineers have to cut down the distance.
If you halve the distance it needs to travel, the wave will reflect off the node position, go back to the anode, and return. This is the second harmonic wave. This effect keeps happening until the node is opened. In most automotive application the intake tract is tuned to the 4th or 5th Harmonic wave.
If your brain hurts yet, don't feel bad lol