The seventh octave is the first octave range of notes above the top of a piano. Using middle C (C4) as a guide, the next higher C is C5 or tenor C, one octave higher. The next C is C6 or soprano high C. The next C, one otcave higher is eight notes away from the last note on the 88 key piano or C8. The seventh octave is the range of notes between C7 and C8. Only a small percentage of coloratura sopranos are capable of altitude in this octave. While notes in the sixth octave, between Soprano High C and C7, can have enough color to sound flutey or canary-like (which give the flageolet register  its name), the harsh, piercing qualities of notes in this octave help give the whistle register it's name. Examples of singers capable of this altitude vocally include Minnie Riperton, Mariah Carey, Chanté Moore, Rachelle Farrell, Shanice Wilson, Debelah Morgan, and while much rarer in men, Adam Lopez of Brisbane, Australia.