Kanto Audio Editor lets you customize your MIDI and MP3 files and make them personalized and optimized for your voice.
You can change tone, volume, and tempo of your MIDI / KAR / MP3 files and save the changes on a new MID / KAR / MP3 file. You can also convert MIDI and KAR to MP3 Karaoke file, preserving lyrics and the tone/volume/tempo desired.