Increase sound file voice

How can I increase the sound level of an MP3 file in asterisk where I play mp3 file using
MP3Player(abc.mp3)

Please see the answers to this question when asked last week.

The best solution is to renormalise the MP3 files before giving them to Asterisk, preferably actually giving Asterisk the signed linear file that would be produced as an intermediate, as that is much more efficient for it to hanle.