Edge Tones with Turbulent Air Sheets
A. T. Jones · The Journal of the Acoustical Society of America · 1942
When the wind from the slit comes fast enough, and the opposing wedge is not too close to the slit, the edge-tone frequency changes continuously with changing slit-wedge distance or changing pressure, instead of exhibiting “jumps” in pitch. The pitch may change continuously through several octaves, and throughout this range the frequency N and slit-wedge distance h satisfy approximately the relation Nh1.45=const. The velocity of the air is so high as to make it likely that the motion is turbulent, and that the frequency is not related to any discrete vortices. The tone is probably maintained by the injecting of masses of air, first on one side of the wedge and then on the other. The resulting compressions cause an alternating flow that carries the air sheet from one side of the wedge to the other. This alternating flow passes through the constriction between slit and wedge, and by making use of the Bernoulli change in velocity in this constricted region it is possible to account for the various phenomena observed.