check out this karate terms and Kanji manual, the basic vowel sounds for A, I , U, E, O and Kana are presented very well:
https://seitouryukarate.com/wp-content/uploads/2012/11/GoJu-Ryu-Karate-Terms-and-Kanji.pdf
It goes over Goju Ryu terms, but many karate style use the same terms.