The onset and coda are the consonantal margins of a syllable, flanking the vowel nucleus. Together with the nucleus, they constitute syllable structure. Understanding onset and coda constraints is essential for predicting L2 pronunciation difficulties.
| Component | Position | Definition | Examples |
|---|---|---|---|
| Onset | Before the nucleus | The consonant(s) that precede the vowel | /str/ in string, /p/ in pin, ∅ in at |
| Nucleus | Centre | The vowel (or syllabic consonant), the sonority peak | /ɪ/ in pin, /iː/ in see |
| Coda | After the nucleus | The consonant(s) that follow the vowel | /ŋ/ in ring, /ŋkθs/ in strengths, ∅ in go |
A syllable without a coda is open (e.g., go /ɡəʊ/, tree /triː/). A syllable with a coda is closed (e.g., cat /kæt/, strengths /streŋkθs/).
English onsets are optional: syllables can begin with a vowel (at, eye, in). When present, onsets can contain up to three consonants:
Most English consonants can occur as single onsets, with restrictions:
| Pattern | Examples |
|---|---|
| /s/ + voiceless plosive | /sp/ spin, /st/ stop, /sk/ skin |
| Plosive + approximant | /pl/ play, /tr/ tree, /kl/ clean, /kr/ cream |
| Fricative + approximant | /fl/ fly, /fr/ free, /θr/ three, /ʃr/ shrink |
Banned: */tl-/, */dl-/, */pw-/, */bw-/, */fw-/
Always /s/ + voiceless plosive (/p t k/) + approximant (/l r w j/):
English codas are also optional but permit far more complexity than onsets, up to four consonants:
Most consonants can occur in coda position, with restrictions:
| Size | Examples |
|---|---|
| CC | /lp/ help, /nd/ hand, /ft/ left, /kt/ act |
| CCC | /mpt/ attempt, /nts/ prints, /ksθ/ sixths |
| CCCC | /ksts/ texts, /lfθs/ twelfths, /ŋkθs/ strengths |
Inflectional suffixes (-s, -ed) regularly create complex codas that would otherwise not exist.
Onsets and codas generally follow the Sonority Sequencing Principle (SSP): sonority rises from the margins toward the nucleus.
Sonority scale (low to high): plosives < fricatives < nasals < liquids < glides < vowels
This means onsets tend to go from low sonority to high (pl-, fr-, sn-) and codas from high to low (-lk, -nd, -ft). English /s/ is a systematic exception because it violates the SSP in clusters like /sp-/, /st-/, /sk-/ and /-ps/, /-ts/, /-ks/.
| Language | Onset pattern | Coda pattern |
|---|---|---|
| English | ∅ to CCC | ∅ to CCCC |
| Vietnamese | ∅ to C (no clusters) | ∅ to C (/p t k m n ŋ/ only) |
| Japanese | ∅ to C | Only /n/ |
| Arabic | C required (no onsetless syllables) | ∅ to CC |
| Mandarin | ∅ to C | Only /n ŋ/ |
| Spanish | ∅ to CC | ∅ to CC (limited) |
Learners from CV languages (Vietnamese, Japanese) must acquire onset clusters that do not exist in their L1. Common repair: epenthesis (street → [sətəriːt]) or cluster reduction (play → [peɪ]).
Coda problems are even more widespread:
In connected speech, coda consonants are regularly resyllabified as onsets of the following syllable when it begins with a vowel:
This resyllabification follows universal preference for onsets over codas and is an important feature for learners to acquire for natural-sounding connected speech.