|Acoustics of the clarinet
Notes are the written pitch.
This curve is qualitatively similar to that for D4 and A5 in the registers below, although the first two peaks have been weakened and shifted by the speaker key and left index finger hole acting as register holes. See the discussion of the altissimo register on the note C#5.
Sound spectrum of a Bb clarinet played using fingering for F#6.
For more explanation, see Introduction to clarinet acoustics
You can hear F#6 played.