You can barely hear the other person or they cannot hear you: speaker, microphone or board
How a service center checks the earpiece, microphone, meshes, flex cables and board lines when the complaint is about sound.
Sometimes the issue really is a clogged mesh, a damp microphone or a worn speaker. But there are also cases where the sound disappears because of a flex cable, a connector or the board itself.
The exact complaint matters too. It is one thing if you can barely hear the other person, another if they cannot hear you, and yet another if the distortion appears only in messengers or only on loudspeaker. Each version points to a different part of the chain.
That is why a good repair process does not begin by replacing the first suspicious part. It begins by identifying which exact component path is responsible and whether the symptom can be reproduced reliably during testing.
If the device has been through moisture, impact or a poor previous opening, the chance of a deeper cause becomes higher. In those cases, replacing the microphone or speaker may help, or it may change nothing because the real fault sits further down the audio path.
The final result in audio complaints almost always depends on careful diagnostics. Here, methodical checking is what usually leads to a proper outcome, not the speed of the first guess.