[ストロボ・EdGE]

It's probably constantly changing, no? She used to be able to hit certain notes back in the day but now she's huskier.

I don't know anything about vocal range or octaves, but the once immensely popular Jpop singer (who is still active) named Misia has a five octave vocal range and she sings well, really amazing and can hit notes that most can't. What I'm trying to get to is that Ayu's is probably lower (?).