The Whistle Register
The whistle register is the highest register in a human's
voice. It's also called super head voice, flute register and
flageolet register. The sound produced in this register
usually sounds like a flute. It's not used often in opera
and pop music, however, interest has increased due to
commercial artists using this register. The most famous
pop artist who frequently uses this register in her music
is Mariah Carey. She reached F7 in a live performance
of her hit single "Emotions". Usage of the whistle register
is mostly for decorative purposes. Another famous "whistle register user" is Yma Sumac. In several recordings she imitates bird sounds quite authentically.


Whistle Register in opera
Some of the Bel Canto operas require notes that
are considered to belong to the Whistle Register. Coloratura Sopranos are the only ones using this range.
The most famous opera requiring such high notes is
Queen of the Night aria in Die Zauberflöte.


How it works
There is still not much known about this ultra high
register, some even say it's merely the top of the head
voice and shouldn't have it's own name. What we do know
is that it starts somewhere around an E6. It is possible
to produce lower notes through the whistle register. It is
believed to start below the E6 in males, and around that
tone in females. Your regular range and voice type can
also influence where exactly it starts. It's not a register
that you can just access without any practice. It's also
not known whether everyone possesses this register.

If you have not "found" your whistle register yet you
can try doing some exercises in your top range. The first
few sounds coming from this register will probably sound
like a small squeak. The sound is light and not strong.
It may take several years before you are able to
effectively control your whistle register. Please note
that you will need to be careful not to strain and/or
damage your voice with incorrect exercises. Do not
exercise the top range for more than a few minutes per
day. If you are feeling strain than stop immediately.
A good voice teacher may be able to tell you more about
finding and training your top range. It's not worth
damaging your voice just to find a few extra notes
that you may never use.