I'm pretty sure Yma could have gone higher. But she did hold the highest Note I believe but only by a half step since the highest by opera singers was C7. Her range is in fact 4 octaves. Some singers inaccurately exploit their range. Mariah's is less than five octaves and as is Yma's. Yma's lowest note is in the 2nd octave. I forgot what note it is but it would have to be C2 for her range to be 5 octaves which it isnt. However they can stay since this category seems useless and not very well varified. And Misia's highest notes are like G6's or A6's.