Tin whistle
In recent years a number of instrument builders have started lines of "high-end," hand-made whistles, which can cost hundreds of dollars US each — expensive in comparison to cheap whistles, but nevertheless cheaper than most other instruments. These companies are typically either a single individual or a very small group of craftsmen who work closely together. The instruments are distinguished from the inexpensive whistles in that each whistle is individually manufactured and "voiced" by a skilled person rather than made in a factory.
Physics of whistles
The diameter of the orifice and cavity is "d", the distance between orifice and cavity is "h", and the orifice pressure "P" was given in kilograms per meter squared. At the lower limit of "h" the second term disappears. In this case, the equation could have been reformatted in terms of the acoustical Strouhal number as shown in the second equation above. The characteristic speed "U" at the nozzle is the sound speed "c". It is interesting that the number is very close to that found by Strouhal for flow over a cylinder. There are two characteristic length scales. Nozzle diameter "d" characterizes the sound power while the separation distance "h" characterizes the frequency.