The microphone on the M100 is located on the bottom of the ear bud, in between the ear tip and LED. If your ear is blocking the microphone, this may result in your voice sounding quiet or muffled and there being extra background noise when taking phone calls.
If this is the case, please ensure that your ear isn’t blocking the microphone.
We would suggest taking a look at the User Guide in the Melomania Connect app, to see the best way of fitting the ear buds in your ear without blocking the microphone.