A viseme is any of several

speech sound In phonetics and linguistics, a phone is any distinct speech sound or gesture, regardless of whether the exact sound is critical to the meanings of words. In contrast, a phoneme is a speech sound in a given language that, if swapped with another ...

s that look the same, for example when

lip reading The lips are the visible body part at the mouth of many animals, including humans. Lips are soft, movable, and serve as the opening for food intake and in the articulation of sound and speech. Human lips are a tactile sensory organ, and can be ...

(Fisher 1968). Visemes and

phoneme In phonology and linguistics, a phoneme () is a unit of sound that can distinguish one word from another in a particular language. For example, in most dialects of English, with the notable exception of the West Midlands and the north-wes ...

s do not share a one-to-one correspondence. Often several phonemes correspond to a single viseme, as several phonemes look the same on the face when produced, such as , (viseme: /k/), (viseme: /ch/), (viseme: /t/), and (viseme: /p/). Thus words such as ''pet, bell,'' and ''men'' are difficult for lip-readers to distinguish, as all look like /pet/. However, there may be differences in timing and duration during actual speech in terms of the visual 'signature' of a given gesture that cannot be captured with a single photograph. Conversely, some sounds which are hard to distinguish acoustically are clearly distinguished by the face (Chen 2001). For example, acoustically speaking English and {{IPA, /r/ can be quite similar (especially in clusters, such as 'grass' vs. 'glass'), yet visual information can show a clear contrast. This is demonstrated by the more frequent mishearing of words on the telephone than in person. Some linguists have argued that speech is best understood as bimodal (aural and visual), and comprehension can be compromised if one of these two domains is absent ( McGurk and MacDonald 1976). Visemes can often be humorous, as in the phrase "elephant juice," which when lip-read appears identical to "I love you." Applications for the study of visemes include

speech processing Speech processing is the study of speech signals and the processing methods of signals. The signals are usually processed in a digital representation, so speech processing can be regarded as a special case of digital signal processing, applied t ...

speech recognition Speech recognition is an interdisciplinary subfield of computer science and computational linguistics that develops methodologies and technologies that enable the recognition and translation of spoken language into text by computers with the ...

, and

computer facial animation Computer facial animation is primarily an area of computer graphics that encapsulates methods and techniques for generating and animating images or models of a character face. The character can be a human, a humanoid, an animal, a legendary creatu ...

References

* Chen, T. (1998, May). "Audio-visual integration in multi-modal communication". ''Proceedings of the IEEE'' 86, 837–852. * Chen, T. (2001). "Audiovisual speech processing". ''IEEE Signal Processing Magazine'', 9–31. * Fisher, C. G. (1968). "Confusions among visually perceived consonants". ''Journal of Speech and Hearing Research'', 11(4):796–804. * McGurk, H. and MacDonald, J. (1976, December). "Hearing lips and seeing voices". ''Nature'', 746–748. * Patrick Lucey, Terrence Martin, Sridha Sridharan (2004). "Confusability of Phonemes Grouped According to their Viseme Classes in Noisy Environments". ''Presented at Tenth Australian International Conference on Speech Science & Technology, Macquarie University'', Sydney, 8–10 December 2004
Article online
(PDF document) Facial expressions Linguistic units Phonology

See also

References