Speech sound

• continuant (incomplete closure of the oral vocal tract)
  • subclasses
    • fricative
    • approximant ("frictionless continuant")
      • subclasses
        • vowel
• sonorant (continuous, non-turbulent airflow in the vocal tract)
  • contrast: obstruent
  • subclasses
    • approximant
      • subclasses
        • vowel
    • nasal
  • Note: does not contain fricative
• obstruent (obstructing airflow, causing a strong gradient of air pressure in the vocal tract)
  • subclasses
    • stop ("plosive")
    • fricative