Normalize audio

First, make a copy of the file. Then do one of the following:

# normalize test.wav

normalizes at -15 dB

# normalize -n 
-n, --no-adjust
Compute and output the volume adjustment that would set the volume to the target, but don't apply it to any of the files (i.e. skip the second phase).  If you use this option, your files will not be altered in any way.
# normalize -a -15dB test.wav

sets average level to -15 dB. The default is very good, so -a is not often necessary.

# normalize -p

uses peak value for basis of the average.

# normalize -l

uses limiter