Also in an average transceiver, the zobel network can be used to absorb all the RF on the speaker wires to stop it getting back into the audio PA. Basically it presents a low impedance to RF. This can make some wild and unexpected noises, particularly with cheap crappy low stability LM386's etc.
The
Boucherot cell does work for differential-mode RF picked up by the xover inductors, within one channel.
But I find stereo loudspeaker wiring makes an excellent dipole antenna for common-mode RF, between the two (L and R) channels.
If you ever scope or RF spectrum analyzer on the loudspeaker outputs, you can see a lot of RF there, more so with MOSFET output stages.
This is the only science I have, as far as audible changes occurring with different audio cables and wiring.
I observe say AM radio station 680kHz with one set of cables, and another set of cables shifts tuning to between local AM stations and less RF interference is seen and heard as mostly "grit" or rectified/demodulated AM roaming around. Not a lot of designers poke around for RF in audio designs.
The fix I use is clamp-on ferrite cores, instead of spending silly money on cables.