WavDelta is a simple filter for .wav files which reduces the size of the file header and delta codes the sound data. It works for .wav files in PCM format at any sample rate and most bit depths. It may not be completely lossless for all files, since it simplifies the file header and rebuilds it during decoding. I've included the full project and vb.net source code with the executable.
music.wav (44,285,996 bytes) -> 7z -> 38,007,792 bytes
music.wav (44,285,996 bytes) -> WavDelta -> 7z -> 30,788,582 bytes