I have always been impressed by the skills of ventriloquists - and I've been wondering lately whether anyone has done any work looking at the acoustic or articulatory properties of the speech of ventriloquists when they are speaking normally and using their skills? Any work on perception of ventriloquist speech would also be interesting.
There doesn't seem to be too much systematical research about the articulatory aspect of ventriloquism, but you could start with these, dealing mainly with substitute sounds:
- Metzner, Jörg & Schmittfull, Marcel & Schnell, Karl (2006): "Substitute sounds for ventriloquism and speech disorders", In INTERSPEECH-2006, paper 1426-Tue3CaP.7.
- Ogawa, Y., Uemi, N. and Ifukube, T. Speech production process in ventriloquism of the phonemes where the place of articulation is lips. IEICE Technical Report, H2000-37, pages 1-8, 2000.
For the (psycho)acoustic and perceptual side of it, the 'ventriloquism effect' is a frequent subject in audio engineering and acoustic (location of loudspeakers, acoustic room design) as well, you can find a lot of research in this area. Concerning crossmodal perception (which clearly makes up a huge part of it), these ones could be a starter:
- Paul Bertelson, Ventriloquism: A case of crossmodal perceptual grouping, In: Gisa Aschersleben, Talis Bachmann and Jochen Müsseler, Editor(s), Advances in Psychology, North-Holland, 1999, Volume 129, Pages 347-362.
- Kanaya, Shoko und Kazuhiko Yokosawa 2010. Perceptual congruency of audio-visual speech affects ventriloquism with bilateral visual stimuli. In: Psychonomic Bulletin & Review, Volume 18, Number 1, 123-128.
Also, a nice study of the perception of ventriloquism in relation to the McGurk effect:
- Bertelson, Paul / Vroomen, Jean / Wiegeraad, Geert / Gelder, Beatrice de (1994): "Exploring the relation between mcgurk interference and ventriloquism", In ICSLP-1994, 559-562.
These are only starting points from a quick and dirty search on the topic. But you should be able to dig a lot deeper from there.
I was told a story once about a paper that Kenneth Pike supposedly delivered on the phonetics of ventriloquism at an LSA meeting -- while LSA still had only one session, according to the storyteller -- but apparently it was never published, because the SIL doesn't have it at http://www.sil.org/klp/klp_biblio.htm.
In the story, Ken walks down the aisle from his seat in the back with a ventriloquist's dummy on his arm, delivering ventrilocal insults to various colleagues via the dummy. Then he has the dummy deliver the paper. This is a pretty consistent Ken Pike story, at least; he was a great showman.
The crux of the paper seemed to be that ventriloquists, who can't be seen moving their lips, simply move the entire phonetic chart as a whole to the inside of the mouth, substituting dentals for labials, palatals for dentals, etc, and ignoring rounding altogether. Thus, no lip movements, though the mouth has to be at least a little open for sound to emerge.
Since the phonemic pattern of each word is shifted regularly, apparently people can get used to understanding the transposed phonetics and hearing it as normal (if perhaps somewhat odd) speech.