| Popis: |
The motion of the reed tongue in early stages of the attack transient has been studied in some detail for reeds from a reed organ. Oscillation waveforms were obtained using a laser vibrometer system, variable impedance transducer proximity sensors, and high speed video with tracking software. Typically, the motion of the reed tongue begins with an initial displacement of the equilibrium position, often accompanied by a few cycles of irregular oscillation. This is followed by a short transitional period in which the amplitude of oscillation gradually increases and the frequency stabilizes at the steady state oscillation frequency. In the next stage, the amplitude of oscillation continues to increase to the steady state value. The spectra derived from the waveforms in each stage have been analyzed, showing that the second transverse mode and the first torsional mode are both observed in the transient, with the amplitude of the torsional mode apparently especially significant in the earlier stages of oscillation. Comparison of reed tongues of different design have been made to explore the role of the torsional mode the initial excitation. Finite element simulations have been used to aid in the verification and interpretation of some of the results. [Work supported by US National Science Foundation REU Grant PHY-1004860.] |
