The files are standard PS ADPCM audio, just in a custom format.
If you rename the audio file to *.vgmstream and paste this into a file called .vgmstream.txth then it should play in Foobar with the vgmstream plugin. Not sure if it will work for other files, but that's the only one I have to test:
codec = PSX
sample_rate = @4:LE$4
channels = @0x10:LE$4
start_offset = 0x800
interleave = 0x400
num_samples = data_size
Can you clarify a bit? I installed both foobar and the plugin, but when I named the unknown extension files with a .vgmstream and tried to open in with foobar, it gives me an error, I also put the files into a folder called .vgmstream.txth and added that folder to foobar and still didn't work, I tried looking for settings for the codec and stuff, but nothing showed to relation on that.
foobar 1.6.7 & foo_input_vgmstream.fb2k-component plugin was used,