I was just scouring the net yesterday for info on this and also searching for the L-3 sound rom to test out some stuff in pinmame. It's ridiculous that Planetary has U5 and U9 posted... somewhat useless if you need a complete set, especially since they are the same between the two L-1/L-3 versions and aren't the critical U2 and U3 chips which did change.
I also noticed that only the L-1 sound rom set appeared to be available. I'm usually pretty good at scouring the net for things, but I just couldn't find it. My pin has L-3 sound currently but I don't have a rom dump of it. If one doesn't appear soon I'll see if I can get a dump to share with ipdb.
I listened through all of the sound samples on the L-1 set and there's some pretty interesting ones that I'm certain never get used, at least not in my L-3 sound/L-6 game rom setup at home.
The music track at 0x07 is actually really pretty cool, but I don't remember hearing it. 0x3e has some weird sort of digital "computery" type sounds. There's a lot of rocket/ufo/jet plane sounds, some of which I've heard some I haven't. Track 0x82 is a slide whistle sound. 0xe5 has Dredd saying "if you do the crime, you do the time" 0x114 is Death saying "Congratulations" There's a couple of Anita Mann saying "Fool" And my favorite - 0x141 says "Dimensional Globe activated" I think they should have just used that... instead of lock/phase.