How to increase volume of microphone

That's usually a bad idea - as it leads to feedback. But, if you want to, and are running Windows 7, open up the Sound control panel. On the Playback tab, click speakers and then properties. In the Levels tab, find the microphone input (Pink perhaps?) and un-mute it. Raise the level above 0 to send your microphone input directly to your speakers. You can also adjust the microphone level input from the Sound control panel. Recording tab, microphone, properties and level. Answered Aug, 10 2011

Use AACGain.

Download and install MP3Gain first, then DL and unzip AACGain.
Copy and re-name aacgain.exe to mp3gain.exe, and move it into the MP3Gain folder, copying over the existing mp3gain.exe.
That's it, now mp3gain should handle AAC's. Answered Jan, 15 2011

It's a firmware issue. go Nokia support dicussions :

E51 low sound in voice calls!!!

Many people has solved the problem by cleaning Microphon cell, it's dirty :)

 

Answered Oct, 22 2010

see here:

How to Increase the Volume of a MP3

http://www.sharewareguide.net/guides/how-to-increase-the-volume-of-a-mp3.html

 

Answered Aug, 26 2010