NPR just ran a piece on people's impressions of famous voices -- Morgan Freeman, Marilyn Monroe, Truman Capote and Patsy Clyne. Details, including an invitation to participate in the second round can be found here. What's striking to me, once I get beyond the über-poetic images people come up with, is how maddeningly difficult it is to get at voice quality, once you get beyond things like what we call creaky voice.
The phonetician John Laver and others have written about 'articulatory range' (with various names for it), as a characteristic of some languages or dialects, but it doesn't seem like that's gone very far. That is, certain varieties (and speakers) tend to have more or less jaw movement, etc. Similarly, Tom Purnell here in Madison has been looking at X-ray Microbeam data on articulation and now talks about 'tongue talkers', who use a lot of tongue movement during speech.
I'm tempted to submit some to the second round of Voice Impressions based on acoustic analysis!