Bettina Dalton
В роли: Narrator (голос)

Iain Morley
В роли: Self - lecturer in palaeoanthropology, University of Oxford

Sophie Scott
В роли: Self - neuroscientist, University College London

Clifford Nass
В роли: Self - professor of communication, Stanford University

Isobel Kirk
В роли: Self - executive voice director, Sydney

David M. Howard
В роли: Self - professor, University of York

Jean Abitbol
В роли: Self - otorhinolaryngologist, Facult? de M?decine de Paris

Christine Kitamura
В роли: Self - psychologist, University of New South Wales

Branka Zei Pollermann
В роли: Self - psychologist, Vox Institute ? Gen?ve

Angélique Kidjo
В роли: Self

Maho Kurashima
В роли: Self - vocal coach

Anne Karpf
В роли: Self - author of book 'The Human Voice'

Krzysztof Izdebski
В роли: Self - founder and chairman, Pacific Voice and Speech Foundation

Hideyuki Sawada
В роли: Self - professor, Faculty of Engineering, Kagawa University

Yoshio Matsumoto
В роли: Self - Service Robotics Research Group, National Institute of Advanced Industrial Science and Technology

Sherry Turkle
В роли: Self - professor, Massachusetts Institute of Technology