Lip reading is much harder than the movies make it look. The youtube channel Bad Lip Reading pokes fun at this by matching funny lines to lip movements. Watch this clip bellow to get a better idea.
The reason they are able to do this, and the reason lip reading is so hard, is that there are few visual cues for English speech Sounds, and many sounds share the same visual cue. Consider the following:
Pressing the Lips Together
Sounds made by pressing the lips together, or bilabial sounds, include /b/, /p/ /m/.
Lip Rounding
Sounds accompanied by lip rounding include: /w/ and vowels in the boot, boy, cow, and boat. There is also a little with “sh” and /r/, though /r/ is mild and more puckered.
Lip Spreading
Sounds made by spreading the lips apart include the vowel in “eat.”
Teeth and Lip
Sounds made by contacting the teeth and lip are called labiodental and include /f/ and /v/.
Tongue Tip Behind Front Teeth
If a speaker opens their mouth wide enough, the lip reader can see when the tongue tip touches the bony outcrop behind the front teeth called the alveolar ridge. Sounds produced this way include /t/, /d/, /n/, and /l/. /s/ and /z/ are also made in this location, but the mouth is usually too closed to see them. That closure is necessary to create the friction needed to create those sounds.
Open Mouth
Sounds produced towards the back of the mouth, /k/, /g/, and to some extent /r/, are accompanied by an open mouth.
How Bad Lip Reading Works
To create a Bad Lip Reading video, the youtuber merely has to watch for the few visual cues described above and match the sounds to them. As long as they choose sounds with the same visual cue, they can substitute almost anything they want. This makes it easy to put words in other people’s mouths.
Before dismissing the importance of visual cues in speech, however, consider the McGurk Effect.
The McGurk Effect
The McGurk Effect occurs when the visual cues don’t match the audio. When this happens, our brains integrate the information, and we perceive a sound somewhere in between. Watch this video, created by professor
Arnt Maasø at the University of Oslo, twice. The first time, keep your eyes closed. Open your eyes for the second time.
The first time you probably heard /ba/ because that was the audio. The second time you likely heard something closer to /da/ because your brain integrated the audio for /ba/ with the visual for the /ga/, so you perceived something in between.
There may not be many visual cues for lip reading, but they are important. Next time you speak to someone who is Deaf or Hard of Hearing, be sure they can see your mouth.
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C.C. The Word Nerd 