Sonority Sequencing Principle

Definition:

The Sonority Sequencing Principle (SSP) states that in any syllable, sonority (the relative loudness and openness of a sound) must rise from the onset to the nucleus and fall from the nucleus to the coda. In practice, this means that the vowel at the center of a syllable is the most sonorous element, and consonants at the edges are less sonorous. This principle governs which consonant clusters are permissible in a language.

In-Depth Explanation

Sonority hierarchy (from least to most sonorous):

1. Voiceless stops (/p, t, k/) — least sonorous
2. Voiced stops (/b, d, g/)
3. Voiceless fricatives (/f, s, ʃ/)
4. Voiced fricatives (/v, z/)
5. Nasals (/m, n, ŋ/)
6. Liquids (/l, r/)
7. Glides (/w, j/)
8. Vowels (/a, i, u, e, o/) — most sonorous

Under the SSP, a well-formed syllable onset must rise in sonority toward the vowel:

• “play” /pl-eɪ/ — stop → liquid → vowel: ✓ sonority rises
• “spray” /spr-eɪ/ — fricative → stop → liquid → vowel: ✓ rises (with /s/ as a special case)
• “lp-” would be ill-formed — liquid → stop: ✗ sonority falls before the vowel

The SSP explains why certain consonant clusters feel “pronounceable” across languages and others don’t.

SSP and Japanese:

Japanese has extremely strict syllable structure — overwhelmingly (C)V (consonant + vowel) or V (vowel alone), with very limited codas (only the moraic nasal /ɴ/ and the first half of geminates). This means Japanese essentially maximally satisfies the SSP: every syllable rises directly from (at most) one consonant to a vowel. No complex onsets, no complex codas, no consonant clusters to evaluate.

This is why Japanese learners of English struggle with English consonant clusters: clusters like /str-/ (“street”), /spl-/ (“splash”), or /-lpts/ (“sculpts”) don’t map onto Japanese syllable structure at all. The typical adaptation strategy is vowel epenthesis — inserting vowels to break up clusters: “street” → /sɯtoɾiːto/ (ストリート). Each inserted vowel creates a new CV syllable, satisfying Japanese phonotactic constraints.

Related Terms

• Phonotactics
• Syllable
• Sonorant
• Obstruent
• Epenthesis

See Also

• Japanese Phonology
• Sakubo

Research

• Selkirk, E. O. (1984). On the major class features and syllable theory. In M. Aronoff & R. Oehrle (Eds.), Language Sound Structure (pp. 107–136). MIT Press. — Formal statement of the SSP and its role in syllable theory.
• Clements, G. N. (1990). The role of the sonority cycle in core syllabification. In J. Kingston & M. E. Beckman (Eds.), Between the Grammar and Physics of Speech (pp. 283–333). Cambridge University Press. — Influential refinement of the SSP with cross-linguistic evidence.