Acoustics of baroque, classical and modern flutes

modern flute
B foot

C7
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

Impedance

Fingering
 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 C7 with gizmo. Z is plotted in dB, i.e. 20 log(Z/Pa.s.m-3).

This fingering is comparable to that for F4 except for the use of one of the G# keys and the LH thumb key as register holes. Comparing this with the F4 impedance spectrum, we see that the fifth minimum is a little deeper. The first minimum plays ~C5 and the second ~B5 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. Compare the impedance spectrum with that for C7 on a flute with a C foot, whose working minimum is several dB shallower. The enhanced ease of playing C7 softly is an advantage of the B foot. Closing the last hole independently using the 'gizmo' key increases this advantage: compare with the fingering below.

Sound


Sound spectrum of a modern flute with a B foot played using fingering for C7 with gizmo.

As well as the strong harmonics of B6 (~2.2, 4.3, 6.5 kHz), you can see very weak maxima in the sound spectrum at about 1100 Hz. Looking up, you'll see that this corresponds to a minimum 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 second impedance minimum. 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 C7 with gizmo played by Geoffrey Collins.

Alternative Fingering

modern flute B foot

Impedance

Fingering
 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 C7 without gizmo.

Comparing it with that for the same note fingered with the gizmo, we note here the shallower minimum for the working minimum (the seventh).

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.