Well, you will be surprised. The most common reason for the quieter sound of one of the TWS headphones that I have encountered (and I have probably counted it on the website by three digits) was... "honey". Or, professionally speaking, WAX. Very often, these headphones have a very fine mesh/strainer at the outlet. And during use, earwax gets into these micro holes and gradually clogs them, the effect is as described above.
Effective cleaning is not easy - because even if you have something to dissolve it, it is difficult to prevent all the mess from flowing inside, onto the membrane, after successful dissolution.
Months of experience allowed me to come to certain solutions. Sometimes it helps to "brush" the grid - a fairly hard toothbrush may be useful. It will help if the crap is only on the surface. If it got deeper, or we pushed it there when trying to remove it, then we move on to more drastic methods. One of them is simply making one or more holes in the mesh. I do it with a sharp, thin needle. It is important to hold it right next to the blade to penetrate it as shallowly as possible. Fortunately, the membrane in GRP is quite far from the mesh, so inserting the needle 1-2 mm into it should not touch it.
While punching holes, we constantly monitor the sound. Often, after making a hole, the "operated" earphone starts playing louder than the supposedly good one. Then we punch holes in both of them and this usually solves the problem.
You can also remove the strainer completely - but I don`t recommend it, as the sound of the headphones often changes. Manufacturers determine the transmission characteristics taking into account the transmission of sound through the strainer. Unfortunately, removing it completely may worsen the sound. If someone has already done it and is now scratching their head what to do with it - you can experiment with different "plugs". In one case, I improved the sound by inserting cotton balls. They muffled the high tones a bit and it was listenable. You can also test different sponges - some headphones have a sponge under the strainer.
Is it possible to prevent clogging? Definitely slow down - with clean ears
NOTE - before starting cleaning, you should exhaust all "non-invasive" methods - i.e. unpairing and re-pairing, resetting, resetting to factory settings, etc.
