The document discusses various theories and concepts related to syllables, including:
1) Syllable structure consists of an onset, nucleus and coda. The nucleus is usually a vowel.
2) Sonority theory proposes that syllables correspond to peaks in airflow, with more sonorous segments like vowels forming syllable nuclei.
3) Prominence theory defines syllables as speech units with peaks of prominence from factors like stress, duration and pitch.
4) Chest pulse theory associates syllables with increases in air pressure during speech.