the sound of 'a' is not as in 'apple' , but the 'u' in understand.
the 'a' in romanised is like in 'ah', while the 'e' is like in 'elephant'. it's really simple, so i get extra annoyed when people don't get it right. 'i' is as in 'it', 'o' in 'octopus' and 'u' as in 'flute'.
if you really want...