@fanch35
Bonjour, même constat ici pour le volume : volume réduit à 10-15%, c'est largement suffisant. Testé avec différents casques (hifi, baladeurs).
J'ai aussi constaté des différences de niveau entre les sons, mais ce n'est pas, de mon point de vue, gênant.

Definitively not at the same complexity level, nor investment, my quick & dirty solution is to use a piece of rubber hose, cut on its length, and rolled on itself, providing a reduction of section.

With changing the hose diameter, when bigger will require more turns, hence reducing even more the remaining air passage.)
The only issue is to not lose it after cleaning !

Hi Clint, I confirm I had the same finding. Indeed, it is an interesting feature (pinky pads might be found a bit too aside the row.