If Bluetooth is connected, the phone chimes only in earphone and not through phone speaker. As earphones are not always in the ears, but hanging to neck we miss many notifications. Any fix for this?

I am facing microphone problems with my M 52 5G (3 months old). The microphone slowly stops catching the voice. The voice becomes feeble and feeble that the person on the other side can't get my voice. Then one day it stops. The phone works normally ...