・ Plural vowels
Pronounce vowels in succession: "a-a, a-i, a-o" and so on. Next, practice pronouncing three vowels such as "a-a-a" and "o-a-i." Then try four or five vowels.
・ Long vowels
Try to prolong each vowel in one breath (the amount of air taken in inhaling once): "aaa, iii, uuu, eee, ooo."
Strain the abdominal muscles slightly at the beginning of the pronunciation and increase the pressure gradually to prolong a vowel. Maintain constant pressure during pronunciation. If you can prolong a vowel for a few seconds in this way, you have succeeded.
・ Word exercises
Practice the following words as one which consists of both vowels and consonants on a long vowel.
Three-syllable words:
atama, otoko, karasu, kimono, kemuri, sushiya, susuki, taiko, tanuki, tsutsuji, namae, makura, moderu, yukata, hechima.