What does a tunable whistle do. I searched the net but could not find any answer.
Sorry maybe you had this question many times
Umm…it just sits there until someone picks it up to play, then it just whistles.
A “tunable whistle” means means that the overall length of the tube can be lengthened or shortened by one of a couple means in order to get the basic pitch of the instrument in tune either to a standard pitch reference or other instruments. A shorter tube gives a higher pitch and a longer tube gives a lower pitch. Atmospheric variables such as temperature and air pressure have an effect on the pitch of a whistle. So a whistle maker may make an in-tune whistle one summer day in Phoenix, Arizona that will need to be adjusted to play in tune in say St. Moritz, Switzerland in the winter. Making a whistle with a tuning slide or a movable head can help mitigate those issues.
A tunable whistle does not change the scale (relative pitch between notes) to which the whistle is made. So players usually tune to a note in the mid-range of the whistle to get into tune - say the first octave A on a D whistle. Then everything else is relative to that note.
Hope that helps.
Feadoggie
I believe Dennis explained it very well. 
I’m used to seein 'em drool and piddle on occassion - oh, and mix cocktails in a pinch. I’ve also tried breedin 'em, but I mostly just end up with mutants. Then there was this one time I used one for making a sandwich… but you gotta put a whole lotta beer through it before it does something like that. 
