A new audio format you say, consider me interested.
What windows calls a wave file is actually a non trivial format (
https://ccrma.stanford.edu/courses/422/projects/WaveFormat/ ) although we have seen that format in games before (most notable electroplankton). The DS does support various things that might be contained in the format and we have also seen PCM audio in N+, that is getting very off topic though and you can read more about all that sort of thing
http://gbatemp.net/threads/the-various-audio-formats-of-the-ds.305167/ (looks like I will have to redo some of the formatting mind you).
Looking at the game (a very interesting selection of formats for others that might want to go through it by the way- tim graphics - it can't be the one playstation formats of the same name can it) I would agree the .waves are probably the sound; I certainly see no SDAT or other known formats unless they are buried in an overlay or the binary.
Knowing straight PCM audio is used on occasion and the DS hardware supports various flavours of PCM and ADPCM I busted out audacity before I even went in for a hex editor. Starting with the biggest (mainly because that is how I roll but also because a long song is easier to pick out from noise induced by importing with the wrong settings) I got a bunch of noise from the import raw setting but I expected as much and heard some music underneath it all.
Were it being sensible I would try to run it is desmume and see what settings the audio channels were at there (they are quite odd on occasion).
Second go I import in a flavour of ADPCM, mono, no endian, 22050 KHz and end up with a chipmunks rendition of what is probably the closing song.
Third go I import on VOX ADPCM, mono, no endian and 11025 KHz (a bit low for a song but phone calls are made at about the same frequency). I sense voxadpcm is not ideal (everything I get seems to be clipped or appear brickwalled although that could just be how it was mastered on the DS) and modern audacity seems to have lost the nicer import raw modes (I could not find them among the older releases when I tried the other month either) so you might instead want to find something like goldwave or whatever else is good there these days.
I only checked a handful of smaller files but they appear to be using similar settings- sometimes sound effects are encoded not in ADPCM for various reasons but seemingly not here.
Naturally I had a look in a hex editor
The magic stamp seems to be
C9FB 0C03 0000 0000 which is absolutely nothing in ASCII and then the byte flipped size at 8 hex as it is for loads of DS formats.
The header almost certainly does not end there (I guess the audio itself starts at 40 hex) and a lot of the rest of the header is 0000 although the rest could be settings. I shall have to check more though but the above should allow you to get some ripping done as I do.