modern flute B foot

D7

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

Notes in the fourth octave are well above the cut-off frequency for the flute, so virtually the whole of the bore is involved in the standing wave. It is therefore inappropriate to give qualitative explanations of the impedance spectra in terms of simpler fingerings. Rather, any open holes are acting as register holes, and their exact placement affects the intonation and depth of the working minima.

Notice that all have some deep minima at low frequencies: these cause little inconvenience because the jet is fast for playing altissimo notes. The principal requirement for fourth octave fingerings is to have a minimum whose frequency is approximately correct, whose depth is as great as one can find, but not to have any other substantial minima at nearby frequencies. Note that, in the sound spectra, there are small, inaudible bumps at frequencies corresponding to the minima in the impedance spectrum.

Sound

Sound spectrum of a modern flute with a B foot played using fingering for D7.

Sound Clip

You can hear D7 played by Geoffrey Collins.