Im 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 C Her range is in fact  octaves Some singers inaccurately exploit their range Mariahs is less than five octaves and as is Ymas Ymas lowest note is in the nd octave I forgot what note it is but it would have to be C for her range to be  octaves which it isnt However they can stay since this category seems useless and not very well varified And Misias highest notes are like Gs or As