For intelligibility and consistency purposes, menu prompts and recorded messages should all be played loud and clear to the telephone line, and if possible they should all have similar perceptible sound volumes.
It is not always easy to assemble several hundred messages for a telephony voice processing application and have them all recorded at nearly constant and nearly maximum amplitude. Sometimes it may be necessary to combine messages recorded during different recording sessions. These messages may not all have the same sound level.
Here again Vox Studio can help. Vox Studio can automatically normalize the sound energy in all your files. Define the desired maximum sound energy, then sit back and relax while Vox Studio does the dirty work for you.