Vortex sound of the flute and its interpretation
A. Bamberger · The Journal of the Acoustical Society of America · 2008
The flute as an example of flue instruments is investigated for its properties of the jet-labium interaction at 1kHz. The jet and the externally excited acoustic flow in the embouchure especially near the labium is recorded with endoscopic Particle-Image-Velocimetry. Extracting the vorticity the data allows us to calculate the vortex sound according to M. How (1975) . The far field acoustic power of the flute is measured as well and compared with the vortex sound power, which matches in sign and magnitude up to a factor 2 for different sound levels. The non-trivial interpretation of the sound production is based on the near cancellation of the two vortex layers of the jet along its path except near the labium. In order to gain insight of the interplay of the different ingredients of the vortex sound power the coriolis force, the acoustic field and their phase relation are determined. Scaling of laws for these quantities as a function of the jet velocity/pressure of the standing wave are deduced and compared with the acoustic power dependence. A comparison with recently available numerical simulations (ISMA 2007) is discussed.