Vowel: pronounced loudly: a o e i u ü ai ei i ao ou iu ie ü ee er an un ng eng 24.
Overall recognition syllables: Zhi Chi Shi Li Zi Ci Yi Gi Wu Yu Yu Ye Yuan Yinyunying 16.
Monovowel: Pronunciation is loud and long. a o e i u ü 6。
Compound vowel: ai ei ui ao ou iu ie ue er 9.
Pronasal vowel: an en in un ün 5
After nasal vowel: eng ing ong 4.
Er is a special vowel, sometimes classified as a compound vowel and sometimes as a special vowel alone.