WavExtractor

WavExtracto is a lightweight and portable app which helps you extract the audio stream of Audio Video Interleave files and save them to the Wave format. It can be easily handled, even by first-time users.
Since this is a portable piece of software, installing WavExtracto is not necessary. It means that you can save the tool to a removable device (like a USB flash drive), store it on any computer and directly run its executable file.
The most important aspect is that the Windows Registry does not receive new entries (thus, minimizing the risk of OS crashes), and no leftover files can be found on the hard drive after program removal. On a side note, you can carry WavExtracto in your pocket when you're on the move.
The interface of the app clearly does not excel in the visual department but it's pretty intuitive. Loading an AVI file can be done by using only the file browser, since the 'drag and drop' functionality is not incorporated. It's not possible to process multiple items simultaneously.
So, you can preview the clip in a built-in media player, view the current and total time along with its location, and trigger the conversion option by pressing a button. Once you establish the output directory and filename, the new audio track is delivered in the given location.
The audio extraction program requires a low-to-moderate amount of system resources, has a good response time, quickly finishes a task and outputs tracks with a good audio quality. We have not encountered any error notifications during our evaluation and WavExtracto did not hang or crash. Although the tool comes with limited features, we must keep in mind that WavExtracto has not been updated for a very long time.