www.fdanews.com/articles/115041-new-devices-aid-deaf-people-by-translating-sound-waves-to-vibrations

New Devices Aid Deaf People By Translating Sound Waves to Vibrations

March 2, 2009

Lip reading is a critical means of communication for many deaf people, but it has a drawback: Certain consonants (for example, p and b) can be nearly impossible to distinguish by sight alone.
ScienceDaily