For the longest time I didn't know about the ADPCM (it wasn't mentioned in any of the mags and I figured the Turbo was doing all of the non-redbook sound work, including all of the streamed voices. I was almost kind of sad to find out that was not the case. Anyway with the quality of the ADPCM being what it is, it is indeed hard to tell what would be making the sound... the Turbo or the CD ADPCM chip. I'm under the impression that anything sampled in CD games comes from the PCM chip (unless it is simply a HuCard game on a CD, etc). Maybe there is some way to see what channels do what in an emulator? I'm pretty sure that the cool growls and yells in Lords of Thunder are ADPCM, and they are obviously loaded into memory and not streamed.
On the Genesis 1 + Sega CD 1 it is easy to tell what is making a sound if you have it hooked up with the included mixing cable. Just turn down the volume on the Genesis 1 and every sound you hear will be from the CD unit. All of the Genesis-made sounds will go away.
I tried a few CD games the other day, while playing with the ADPCM volume in Magic Engine. They all used
only the ADPCM for sampled effects.

Some of the games were Lords, Drac X, World Heroes 2, Kabuki Itouryoden and Dragon Slayer.
Which is kinda lame, since so much more could be done with the CD format and multiple sound channels(which no longer need to get eaten up by PSG music).
Anyways, here's some TurboGrafx HuCard voice clips-
http://www.superpcenginegrafx.com/TurboGrafxVoiceExamples.mp3And here are samples from the same games, but with a bunch more-
http://www.superpcenginegrafx.com/TurboGrafxVoiceExamples.mp3Champions Forever is a good example of what could've been done in more HuCards with sampled sounds. But it also shows how the ADPCM should've only been a part of the digitized sfx in CD games.