Use Flac Audio Format For Archives Rather Than Wav

From The Production of Speech Corpora, Compression chapter:

By using standard compression algorithms you may reduce the total amount of speech data to 55-65% depending on the technical specifications of your speech signals12.3. There also exist special compression algorithms for speech12.4, but we found that they do not yield significantly better compression rates than standard algorithms (like gzip, zip) when used in `loss-less' mode12.5.

However, we do not recommend using compression at all. Working with uncompressed data directly from the distribution medium is much more convenient, while on the other hand the reduction of costs do not justify the additional effort. Furthermore, by using compression on your distribution media you'll increase the probability of software incompatibilities on the user side.