There are some Perl programs around to do the conversions, but they usually use sox. There are alot of docs ,tutorials, and tips available for the right syntax for the conversion. For example, search groups.google.com for " sox A-law U-law" and you will find answers.

Here is basically how you would run sox thru system.

#!/usr/bin/perl
use warnings;
#converts 8bit wav files to 16bit

my @files = <*.wav>;
  foreach my $file(@files){
     my ($name) = $file =~ /(.*).wav$/;
    system("sox -b $name.wav  -w $name.16.wav");
}
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