It sounds like corrupted ADPCM sound then, especially if it doesn't affect HuCARDs. I asked about real CDs since it's not impossible that bad reads could cause this, although it's not likely.
As for what could cause this in a Duo R...I don't know. Does it have any mods or repairs or anything?
Try a game with no ADPCM sound in it. I don't know of any but I'm sure they exist, probably some garbage title, see if it still does it.
Also, it's Gate of Thunder, not Gates.