just found out that the so-called defining point of the whistle register is the soprano C. like oh my goodness. never knew that i could actually sing in whistle register. though of course, mine's pretty limited, only till about a G#6 (cos i didn't dare to go any higher due to lack of warmups) and it remains a question as to whether i am actually utilising the register or just extending my own usual register.
interesting, interesting.
and i really should get back to studying><"