Radiation patterns of novel one‐ and three‐tine tuning forks Free

Inspired by recent results [D. A. Russell, Am. J. Phys. 68, 1139–1145 (2000)] showing that the traditional two‐tine tuning fork behaves as a linear quadrupole source, novel one‐tine and three‐tined tuning forks were constructed. The three identical tines on the three‐tined fork were equally spaced around a circle and oriented so that each tine oscillated radially when exciting the fundamental mode. The angular dependence of the radiated sound from these forks was investigated as a function of distance from the symmetry axis of each fork. In the near field, the three‐tined fork has three major maxima, one adjacent to each tine, and three minor maxima, one opposite each tine. The minor maxima disappear in the far‐field measurements. These results were compared to a simple model wherein each tine behaves as an independent point dipole source [P. M. Morse and K. U. Ingard, Theoretical Acoustics, 2nd ed. (Princeton U.P., Princeton, NJ, 1986), p. 313]. The simple model shows good, but not perfect, agreement with the measured radiation patterns.