Viseme

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Vowel lip shapes in a 1919 lip reading manual Vowel lip shapes.jpg
Vowel lip shapes in a 1919 lip reading manual

A viseme is any of several speech sounds that look the same, for example when lip reading (Fisher 1968).

Visemes and phonemes 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 /k,ɡ,ŋ/; as well as /t,d,n,l/ , and /p,b,m/). Thus words such as pet, bell, and men are difficult for lip-readers to distinguish, as all look like alike. On one account, visemes offer (phonetic) information about place of articulation, while manner of articulation requires auditory input [1] .

However, there may be differences in timing and duration during natural speech in terms of the visual "signature" of a given gesture that cannot be captured by simply concatenating (stilled) images of each of the mouth patterns in sequence [2] . Conversely, some sounds which are hard to distinguish acoustically are clearly distinguished by the face. For example, in spoken English /l/ and /r/ can often sound quite similar (especially in clusters, such as 'grass' vs. 'glass'), yet the visual information can disambiguate. 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 recognition, and computer facial animation.

See also

Related Research Articles

<span class="mw-page-title-main">Allophone</span> Phone used to pronounce a single phoneme

In phonology, an allophone is one of multiple possible spoken sounds – or phones – used to pronounce a single phoneme in a particular language. For example, in English, the voiceless plosive and the aspirated form are allophones for the phoneme, while these two are considered to be different phonemes in some languages such as Central Thai. Similarly, in Spanish, and are allophones for the phoneme, while these two are considered to be different phonemes in English.

Approximants are speech sounds that involve the articulators approaching each other but not narrowly enough nor with enough articulatory precision to create turbulent airflow. Therefore, approximants fall between fricatives, which do produce a turbulent airstream, and vowels, which produce no turbulence. This class is composed of sounds like and semivowels like and, as well as lateral approximants like.

<span class="mw-page-title-main">International Phonetic Alphabet</span> System of phonetic notation

The International Phonetic Alphabet (IPA) is an alphabetic system of phonetic notation based primarily on the Latin script. It was devised by the International Phonetic Association in the late 19th century as a standard written representation for the sounds of speech. The IPA is used by lexicographers, foreign language students and teachers, linguists, speech–language pathologists, singers, actors, constructed language creators, and translators.

A phoneme is any set of similar speech sounds that is perceptually regarded by the speakers of a language as a single basic sound—a smallest possible phonetic unit—that helps distinguish one word from another. All languages contain phonemes, and all spoken languages include both consonant and vowel phonemes. Phonemes are primarily studied under the branch of linguistics known as phonology.

In phonetics, a phone is any distinct speech sound or gesture, regardless of whether the exact sound is critical to the meanings of words.

Phonetics is a branch of linguistics that studies how humans produce and perceive sounds or, in the case of sign languages, the equivalent aspects of sign. Linguists who specialize in studying the physical properties of speech are phoneticians. The field of phonetics is traditionally divided into three sub-disciplines on questions involved such as how humans plan and execute movements to produce speech, how various movements affect the properties of the resulting sound or how humans convert sound waves to linguistic information. Traditionally, the minimal linguistic unit of phonetics is the phone—a speech sound in a language which differs from the phonological unit of phoneme; the phoneme is an abstract categorization of phones and it is also defined as the smallest unit that discerns meaning between sounds in any given language.

Phonology is the branch of linguistics that studies how languages systematically organize their phonemes or, for sign languages, their constituent parts of signs. The term can also refer specifically to the sound or sign system of a particular language variety. At one time, the study of phonology related only to the study of the systems of phonemes in spoken languages, but now it may relate to any linguistic analysis either:

Labial consonants are consonants in which one or both lips are the active articulator. The two common labial articulations are bilabials, articulated using both lips, and labiodentals, articulated with the lower lip against the upper teeth, both of which are present in English. A third labial articulation is dentolabials, articulated with the upper lip against the lower teeth, normally only found in pathological speech. Generally precluded are linguolabials, in which the tip of the tongue contacts the posterior side of the upper lip, making them coronals, though sometimes, they behave as labial consonants.

In phonetics, labiodentals are consonants articulated with the lower lip and the upper teeth, such as and. In English, labiodentalized /s/, /z/ and /r/ are characteristic of some individuals; these may be written.

Lip reading, also known as speechreading, is a technique of understanding a limited range of speech by visually interpreting the movements of the lips, face and tongue without sound. Estimates of the range of lip reading vary, with some figures as low as 30% because lip reading relies on context, language knowledge, and any residual hearing. Although lip reading is used most extensively by deaf and hard-of-hearing people, most people with normal hearing process some speech information from sight of the moving mouth.

Labialization is a secondary articulatory feature of sounds in some languages. Labialized sounds involve the lips while the remainder of the oral cavity produces another sound. The term is normally restricted to consonants. When vowels involve the lips, they are called rounded.

<span class="mw-page-title-main">McGurk effect</span> Perceptual illusion

The McGurk effect is a perceptual phenomenon that demonstrates an interaction between hearing and vision in speech perception. The illusion occurs when the auditory component of one sound is paired with the visual component of another sound, leading to the perception of a third sound. The visual information a person gets from seeing a person speak changes the way they hear the sound. If a person is getting poor-quality auditory information but good-quality visual information, they may be more likely to experience the McGurk effect.

<span class="mw-page-title-main">Bilabial click</span> Consonantal sound

The bilabial clicks are a family of click consonants that sound like a smack of the lips. They are found as phonemes only in the small Tuu language family, in the ǂ’Amkoe language of Botswana, and in the extinct Damin ritual jargon of Australia. However, bilabial clicks are found paralinguistically for a kiss in various languages, including integrated into a greeting in the Hadza language of Tanzania, and as allophones of labial–velar stops in some West African languages, as of /mw/ in some of the languages neighboring Shona, such as Ndau and Tonga.

<span class="mw-page-title-main">Voiced labial–palatal approximant</span> Consonantal sound represented by ⟨ɥ⟩ in IPA

The voiced labial–palatalapproximant is a type of consonantal sound, used in some spoken languages, for example, French "huitième", read as [ɥitjɛm]. It has two constrictions in the vocal tract: with the tongue on the palate, and rounded at the lips. The symbol in the International Phonetic Alphabet that represents this sound is ⟨ɥ⟩, a rotated lowercase letter ⟨h⟩, or occasionally ⟨⟩, which indicates with a different kind of rounding.

Voice or voicing is a term used in phonetics and phonology to characterize speech sounds. Speech sounds can be described as either voiceless or voiced.

<span class="mw-page-title-main">Perception of English /r/ and /l/ by Japanese speakers</span> Japanese-language speakers perception of English consonants

Japanese has one liquid phoneme, realized usually as an apico-alveolar tap and sometimes as an alveolar lateral approximant. English has two: rhotic and lateral, with varying phonetic realizations centered on the postalveolar approximant and on the alveolar lateral approximant, respectively. Japanese speakers who learn English as a second language later than childhood often have difficulty in hearing and producing the and of English accurately.

In phonetics and phonology, relative articulation is description of the manner and place of articulation of a speech sound relative to some reference point. Typically, the comparison is made with a default, unmarked articulation of the same phoneme in a neutral sound environment. For example, the English velar consonant is fronted before the vowel compared to articulation of before other vowels. This fronting is called palatalization.

Palatals are consonants articulated with the body of the tongue raised against the hard palate. Consonants with the tip of the tongue curled back against the palate are called retroflex.

Phonemic contrast refers to a minimal phonetic difference, that is, small differences in speech sounds, that makes a difference in how the sound is perceived by listeners, and can therefore lead to different mental lexical entries for words. For example, whether a sound is voiced or unvoiced matters for how a sound is perceived in many languages, such that changing this phonetic feature can yield a different word ; see Phoneme. Another example in English of a phonemic contrast would be the difference between leak and league; the minimal difference of voicing between [k] and [g] does lead to the two utterances being perceived as different words. On the other hand, an example that is not a phonemic contrast in English is the difference between and. In this case the minimal difference of vowel length is not a contrast in English and so those two forms would be perceived as different pronunciations of the same word seat.

A lisp is a speech impairment in which a person misarticulates sibilants. These misarticulations often result in unclear speech in languages with phonemic sibilants.

References


  1. Summerfield Q. Lipreading and audio-visual speech perception. Philos Trans R Soc Lond B Biol Sci. 1992 Jan 29;335(1273):71-8. doi: 10.1098/rstb.1992.0009. PMID: 1348140
  2. @article{Calvert2003ReadingSF, title={Reading Speech from Still and Moving Faces: The Neural Substrates of Visible Speech}, author={Gemma A. Calvert and R. Campbell}, journal={Journal of Cognitive Neuroscience}, year={2003}, volume={15}, pages={57-70}, url={https://api.semanticscholar.org/CorpusID:14153329} }