Found this great little movie with Jack Klugman and Tony Randall, done by the National Centre for Voice Science. A simple review of how the voice works.
Eric Armstrong is the voiceguy. Eric is a dialect, voice, speech and text coach based in Toronto, Canada, where he normally teaches full-time at York University’s Dept. of Theatre. Eric has been teaching voice for the actor full-time since 1994, and has taught in Canada and the US, at the University of Windsor, Brandeis University, Roosevelt University, Canada's National Voice Intensive and York University. He has worked for nationally and internationally recognized companies such as Crow’s Theatre, Volcano, SoulPepper, & Canadian Stage in Toronto, and The Court Theatre and Steppenwolf in Chicago. Eric holds a BFA from Concordia University (Montreal) in Theatre Performance, and an MFA from York University (Toronto) in Acting. His mentors were David Smukler (York, Canada’s National Voice Intensive) and Andrew Wade (Royal Shakespeare Company). He has also studied at the Drama Studio, London, and Il Stage Internazzionale di Commedia dell’Arte in Reggio Emilia, Italy. He’s a long time member of the Voice and Speech Trainers Association, where he has served on the board, as a conference planner, photo editor for the Voice and Speech Review, Founding Director of Technology and Internet Services, and has written numerous peer-reviewed articles, essays and reviews for the VASTA Newsletter, the VASTA Voice, and The Voice and Speech Review.