Acoustics of the saxophone

Bb soprano saxophone


Music Acoustics UNSW


a key depressed
a key not depressed
a hole covered
a hole uncovered
a part of the mechanism that is not normally touched
Details in fingering legend.

Acoustic schematic
a closed tone hole
an open tone hole

Non-specialist introduction to acoustic impedance
Non-specialist introduction to saxophone acoustics

Notes are the written pitch.
Frequencies are the sounding frequency, for Bb saxophone.
Unless otherwise stated, the impedance spectrum is for a Bb saxophone.

Impedance spectrum of a Bb soprano saxophone measured using fingering for G#5.

This is the seventh note in the second register. It differs from G#4 (the corresponding note in the first register) in that it uses a register hole. This causes a leak in the bore that weakens and mistunes the first impedance peak, but has little affect on higher peaks – see register hole for an explanation, and compare with G#4, whose impedance spectrum is almost identical except for the first peak. Above about 1 kHz, the third peak is weakened and the rest of the curve is irregular: see the discussion in cut-off frequency.

This is the highest note to use the first register hole (a small hole, but not the one near the mouthpiece), so the register key is not near the node in this fingering, and hence does not weaken the first peak effectively. The saxophone has an automatic octave key.

Compare with the impedance spectrum for a tenor sax on written G#5: same fingering but sounding one octave lower.


Sound spectrum of a Bb soprano saxophone played using fingering for G#5.
For more explanation, see Introduction to saxophone acoustics.

This fingering is at the extreme range of the low register key, and hence does not weaken the first impedance peak effectively. Consequently, transient excitation of the first impedance peak (and harmonics thereof) at the beginning of the note is necessarily difficult to avoid.

Sound Clip

You can hear G#5 played.

Fingering legend
How were these results obtained?

Contact: Joe Wolfe /
phone 61-2-9385-4954 (UT +10, +11 Oct-Mar)
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