Asking because it's an interesting phenomenon and I don't know enough to understand the question I'm putting forth:

If conductive heat is radiated through quanta, phonons[0], why would it be limited to the speed of sound? Is there a limitation to waveforms in matter that limits the speed at which it travels or is it purely dependent on the energy "type"? (Thinking of light travelling in waveform, when I posit this, which is the reason the ridiculous ask.)

[0] - https://en.wikipedia.org/wiki/Phonon#Acoustic_and_optical_ph...