Vibrational modes of the reed in a reed organ pipe
Abstract
We will describe a series of measurements of the vibrational modes of the reed in a reed organ pipe. These measurements were performed using a Polytec PSV-300 scanning vibrometer, which allows the vibrational deflection shape to be determined at any frequency. In addition to blowing the reed pipe in a standard fashion, a mechanical driver was used to excite the reed. Using both excitation sources, a number of deflection shapes were observed including simple cantilever, torsional, and higher-order shapes corresponding to higher-order cantilever and torsional modes. As expected, the observed frequencies of the mechanically driven modes were not integer multiples of the fundamental, and were consistent with theoretical predictions. The reed pipe was also excited in a standard manner using an organ blower. This raised integer multiples of the fundamental frequency as high as 20 kHz within two decades of the velocity amplitude of the fundamental. Torsional and other deflection shapes were present, however nonlinear interactions in the system caused them to be shifted from their mechanically driven frequencies. In some cases, significant vibration was observed in the tuning wire and the section of reed above the tuning wire that was previously considered to be clamped.
- Publication:
-
Acoustical Society of America Journal
- Pub Date:
- October 2003
- DOI:
- 10.1121/1.4781139
- Bibcode:
- 2003ASAJ..114.2348H