McGurk effect
The McGurk effect shows how hearing and vision are used for speech perception. Named after the man who found it, Harry McGurk (23 February 1936 – 17 April 1998), it says that people hear speech with their ears, and use other senses to help interpret what they hear. The McGurk effect happens when watching a video of a person saying /ga/ with a sound-recording saying /ba/. When this is done, a third sound is heard: /da/.