Mac Forum / Applications / Mac Applications / February 2005

I have not found any gui wrapper for sox to be satisfactory, because sox
has so many abilities that these need to be specified from the command
line.

sox is available here:

<http://sox.sourceforge.net/>

and you'll find an extensive description of its abilities. One of the
things it can do is "channel averaging", which is what you want: that
is, to take a sound file consisting of two channels and make a new sound
file consisting of one channel that averages those two channels
together.

So to turn stereo.wav into a mono file, mono.wav, you would say:

sox -c 2 stereo.wav -c 1 mono.wav avg 0.5,0.5

I'm not saying that sox is good for everything (a good sound editor and
plug-in host such as Amadeus II or DSP-Quattro is obviously invaluable);
I'm just saying that it's so quick and useful for certain basic
transformations like changing one format to another (wav to aiff, for
instance) or the problem you pose (changing stereo to mono) that it's
nice to have it on hand. There are some things for which a display is
simply not needed, and that's when sox comes in really useful. For
example, Amadeus II can easily transform an aiff file to a wav, but in
order to do so, it must open the file and display it; sox can perform
the actual transformation considerably faster than Amadeus can even open
the file.

Instructions for compiling and installing sox are the same as for any
Unix command. You will need to have installed the developer tools. If
the procedure worries you, you can use Fink to do the installation for
you:

http://fink.sourceforge.net/pdb/package.php/sox

m.