For those of you who are not familiar with command-line operations, 
here is how to use the sox program from Windows.

1. download the "sox12181" zip file from SourceForge. Unzip and
extract the sox file to your desktop.

2. In windows: click Start -> All Programs -> Accessories -> Command Prompt.  
A command-line window should appear.

3. In the Command Prompt window, type: cd desktop

4. In the Command Prompt window: (with the sound file you wish to
convert on the desktop as well), type

    sox secret.wav secret.dat 

5. Now you should see the converted file secret.dat on your desktop.

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Here is how to use the sox program from mac.

1. download the "sox-14.4.1" folder from SourceForge to desktop.

2. In mac: go to Dock, click Applications -> Utilities -> Terminial.app  
A commandline window should pop up.

3. In Command Prompt window, type: cd Desktop/sox-14.4.1

4. In Command Prompt window: (with the sound file, such as secret.wav, you wish to 
convert on the sox-14.4.1 folder as well), type

    ./sox secret.wav secret.dat 

5. Now you should see the converted file secret.dat in your sox-14.4.1 folder.