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Department of Linguistics

SPEECH ACOUSTICS

The Acoustics of Coarticulation

Robert Mannell

PDF version of Lecture Slides (1 slide to a page)
PDF version of Lecture Slides (6 slides to a page)
2008 lecture mp3 audio recording (right click to save file)

  • Articulatory gestures overlap
  • Slower moving articulator gestures overlap more than fast moving articulators
  • The effect of overlapping gestures is called coarticulation
  • Phonemes rarely occur in isolation
  • Phonemes are normally articulated as part of a syllable
  • There are no acoustic boundaries between phonemes (except across intonational phrase boundaries which are characterised by pauses). This continuous transitioning between phonemes is a fundamental characteristic of coarticulation
  • Coarticulation is seen in acoustic representations of speech as effects on the formants of vowels and vowel like sounds (sonorant phonemes) and effects on the resonant peaks of non-sonorant consonants
  • We perceive speech by recognising the (auditorily-transformed) acoustic patterns of syllables
  • Coarticulation tends to be stronger within syllables rather than across syllable boundaries
  • Coarticulation is the effect of one adjacent sound on another (and vice versa) and can occur across all boundaries except prosodic boundaries characterised by a pause
  • Vowels affect the articulation of adjacent consonants (and adjacent vowels)
  • Consonants affect the articulation of adjacent vowels (and other adjacent consonants)
  • Some sounds are more resistant to coarticulation than other sounds
  • Coarticulation is greatest when there is the greatest articulator movement between phonemes

Tongue Height and Coarticulation

  • Most lingual consonants have a high tongue position
  • High vowels are least affected by these high consonants
  • Low vowels are most affected by these high consonants

Phoneme Inventory Effects

  • Coarticulation is resisted when it will result in perceptual confusion
  • Vowels coarticulate most in languages with a small number of vowels
  • Consonants coarticulate most in languages with a small number of places of articulation

Locus Theory

Strong Version: All consonants have a fixed target which is realised at a single frequency for each formant. The F2 target for a particular consonant is known as its F2 locus

Weak Version: Consonants don't have a fixed target as their targets are affected by coarticulation, but they do tend to have a locus space for each formant defined by a range of formant frequencies. The target frequency tends to be within this range and depends upon the adjacent sound

The weak version is supported by a vast body of research

Reference

Clark, J., & Yallop, C., (1995), An introduction to phonetics and phonology, 2nd. edition, Blackwell, Oxford, Chapter 7, "The Acoustics of Speech Production". See the section entitled "The acoustic properties of consonants in syllables".

Also revise the phonetics and phonology resource topic on coarticulation.

A useful web site

The following two links are from the SWPhonetics web site of Sidney Wood. He has suggested the following two web pages. You also might like to browse the rest of his website.

http://swphonetics.com/coarticulation/whatcoart/

http://swphonetics.com/methods/cinefluorography/x-ray-movie/