| Popis: |
Musical sands, as well as common materials such as silica gel, emit inordinately intense audible sounds when sheared by wind, waves or other mechanical means. Hand shaken laboratory size samples of these materials produce very coherent beat-like signals, when displayed on an oscilloscope. Frequency parameters of these patterns have been related to particle size, and, more surprisingly perhaps, to sand sample size. By combining these two relationships, a simple method for creating a source of single frequency sound has been developed. It consists of filtering musical sands into narrow size fractions and then tailoring an appropriate size distribution which can be finely tuned to any given frequency within the frequency range defined by the whole sample. Thus, the principles for developing an active device that converts input mechanical energy into a narrow intense beam of coherent audible sound have been established. |
