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.
Whistler (radio)
The first spectrogram through which people heard the whistlers was taken from a 48 second long nightside plasmaspheric pass on March 26, 1996. These whistlers were seen at a frequency below 1.5 kHz.