Hannah is a ten-year-old girl seen in Favorite Word, where her favorite word at the time was "singing".
Singing Hannah is thus a natural nickname for her to distinguish her from Space Hannah.
She looks identical to the character Katy.
Interview for WYFW[]
My favorite word is "singing". I like to sing, because you can sing anywhere. I like to sing personally in the shower, because you can just sing whatever, and no one can make fun of you.