Acoustics of baroque, classical and modern flutes

modern flute
B foot


Music Acoustics UNSW

modern B modern C classical C classical D classical flared baroque B3 B3
C4 C#4 D4 D#4 E4 F4 F#4 G4 G#4 A4 A#4 B4
C5 C#5 D5 D#5 E5 F5 F#5 G5 G#5 A5 A#5 B5
C6 C#6 D6 D#6 E6 F6 F#6 G6 G#6 A6 A#6 B6
C7 C#7 D7 D#7 E7 F7 F#7 multiphonics


a key depressed
a key not depressed
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 flute acoustics

Impedance spectrum of a modern flute with a B foot measured at the embouchure hole using fingering for B6. Z is plotted in dB, i.e. 20 log(Z/Pa.s.m-3).

This fingering is comparable to that for G4 except for the use of one of the trill keys and the LH 2nd finger key as register holes. The register holes create a pressure node (or flow antinode) about three quarters of the way along the pipe, and thus allows B6 but not B4, B5, or F#6. Comparing this with the B4 impedance spectrum, we see that the fifth minimum is a little deeper. The third and fourth are shallower and unplayable. The first minimum plays ~D/5 and the second ~C#6 but, because it is a cross fingering for these notes, their timbres are darker. Combinations of these three notes may be played simultaneously as multiphonics.


Sound spectrum of a modern flute with a B foot played using fingering for B6.

As well as the strong harmonics of B6 (~2, 4, 6 kHz), you can see very weak maxima in the sound spectrum at about 600 and 1100 Hz. Looking up, you'll see that these correspond to minima in Z(f). There is a small but audible amount of turbulent flow – this is an important part of the characteristic flute sound. That turbulence has power at all frequencies and here it excites the first and second impedance minima. If you look closely at the sound spectra for many of the high notes, you will notice a similar effect.

Sound Clip

You can hear B6 played by Geoffrey Collins.

The Virtual Boehm Flute may suggest other fingerings for this note.
Fingering legend
How were these results obtained?
Acoustic measurements are available for these flutes -
modern B, modern C, classical C, classical D, classical flared, baroque
Sound clips are available for modern B, classical flared and baroque
To compare flutes, it is easiest to open a separate browser window for each instrument.

Copyright © Academic Press. JSV+ Joe Wolfe, John Smith, John Tann and Neville H. Fletcher, Acoustics of baroque, classical and modern flutes
Revised to include the baroque flute 2001.