Download Audio Transcoder (see Resources below). Install the program.
Start Audio Transcoder. Click on the "Audio Convert" tab. Browse through the file directory on the left screen and select a WAV audio file. It will appear in the blank screen to the right.
Click on the audio file. Drag the mouse to the empty screen on the bottom. This transfers the audio file into the conversion screen.
On the Output menu below the conversion screen, hit the "Down" button on the "If output file exists" section. Select "Overwrite existing" if you want the converted file to replace the old file. If not, leave it as "Create new file."
In the same Output menu, click the "Down" arrow on the first drop-down menu in the "Output Format" section. Select ".mp4 (Advanced Audio Coding)."
Press the "Convert" button. A conversion pop-up screen will appear showing the progress of the conversion. Wait for it to finish. When it finishes, the pop-up screen will close.