Hey! I was the dude behind our audio for the game. I did indeed record all of the voice lines myself and ran them through a long processing chain to crunch them up properly :--D
I used Plogue's Chipcrusher to downsample the quality and ran it through Ultima DSP's SPS to emulate a PSX sound chip for the output. I kinda wanted to go for something like the old TMNT 4 for SNES or Streets of Rage 2 for Genesis for the voice lines, but our general visual aesthetic and soundscape was a bit closer to PSX so I needed to tone it down a bit :D
Thanks for playing our game and the lovely feedback :)