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
An annular duct carries the fluid that creates the annular jet. The jet impinges on a sharp ended ring with two toroidal cavities on either side. In Levavasseur's patent, a structure is added downstream of the annular opening to act as a coupling horn to direct the sound. The sound generated is very intense. It appears that no scientific study has been done to elucidate the detailed feedback mechanisms of its operation, although it is clear that this whistle has Class I feedback mechanism, similar to the police whistle.