Can you use the "Ha, Heh, Hee, Ho" method for learning Japanese vowels? In Spanish, you can use the "Ha, Heh, Hee, Ho" method for learning Spanish vowels. For example, A in Spanish sounds like the 'a' in Ha! E in Spanish sounds like the 'e' in Heh! I in Spanish sounds like the 'ee' in Hee! O in Spanish sounds like the 'o' in Ho! and then U is like the OO in food. Does this apply to Japanese vowels as well? I have listened to Japanese vowels and they sound identical. But I thought I should double check, so I don't learn them wrongly.

Unless you put stress on them, it works as well. (You may find "U" a little different in New Tokyo dialect, which is a virtual standard, but that's beyond the category of Standard Japanese.) If you put stress on a vowel, it's prolonged and includes pitch shift, which is taken as sequence of two sounds to ears of a Japanese speaker.