The samples are mono XMA files.Download the tools here
I've included the tools necessary (QuickBMS from aluigi, a BMS script from Alpha23 and ToWAV) to decode them into PCM WAV. The samples you provided were at 32000Hz but some of the files might not be. In that case you need to manually adjust the BMS script in a text editor changing it from 32000 to another sample rate (22050, 44100 or 48000) most likely.
Put all the .wav files in the 'QuickBMS' folder and then run the 'Add XMA Header.bat'
After that, then copy all the .xma files generated from that BMS script and put them into the 'ToWAV' folder and run the 'ConvAll.bat' which will transcode them into PCM WAV