Acoustics of baroque, classical and modern flutes

classical flute
C foot


Music Acoustics UNSW

modern B modern C classical C classical D classical flared baroque B3
C4 C#4 D4 E4 F#4
D5 E5 F#5


Acoustic and Fingering Schematic
a covered tone hole or key pressed
an uncovered tone hole or key not pressed
a partly covered hole

Details in fingering legend.

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

Impedance spectrum of a classical flute with a C foot measured at the embouchure hole using fingering for C4. Z is plotted in dB, i.e. 20 log(Z/Pa.s.m-3).

This is the lowest note on this flute. All tone holes are closed, so the bore most closely resembles a truncated cone on the end of a cylinder, and there is no tone-hole filtering at high frequencies. As a result, the regular series of minima (and maxima) in Z(f) extends to high frequencies. The gradual rise at high frequencies is due to the overall geometry: the chimney is in series with the parallel combination of the main part of the bore and the short section between the closed end and the embouchure. The first several minima can be played, but usually flute players only play the first, for which the higher minima aid the production of harmonics. Details on the all-closed fingering at lowest note.

Compared with C4 on the Boehm flute, the impedance minima on the classical flute become shallower more quickly at high frequencies. This is because the narrower pipe produces higher viscous losses near the wall, which are more important at high frequency. When played, this means less power in the standing waves at higher harmonics, and less power radiated, as is seen in the sound spectrum. The smaller tone holes radiate less power than those of the Boehm flute, so the classical flute is quieter.


Sound spectrum of a classical flute with a C foot played using fingering for C4.

Sound Clip

You can hear C4 played by Geoffrey Collins.

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.