I agree, the dream almost surely means that you’re stressing out too much and working too hard on your whistle (or, alternatively, you could be stressing -instead- of working hard, I’ve seen people do that, but it’s less likely. I, of course, have never done so with any topic… yeah, that’s the ticket…
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Anyway, I recommend against doing any kinds of ‘exercises’ with the whistle… speed comes by trying to play faster, and eventually succeeding. You can do this by playing exercises, or by playing tunes… and tunes are -much- more fun (usually). Of course, if you get sick of the tunes that you know and still would rather practice speed than learn a new tune, you can do exercises, and I certainly did enough scales until I could do a running-trill up and down both octaves from low D to d-above-high-D and back down. Do not do this when other people can hear you, at least not at first… there’s a -reason- that D-above-high-D is not listed as a possible note in most whistle instructions.
Or you could just play around. The most important piece in the book ‘how to play the piano despite years of lessons’ (which I recommend to anyone interested in western music of any flavor on any instrument, for its wit and for its explanation of ‘music theory’ in easy terms for the musical enthusiast … not a ‘made easy’ book by any means, but a ‘made clear’ book…) … where was I? Oh yes, the most important line is ‘As ye fool around, so shall ye find!’ … in otherwords, when lacking for a tune to play, just mess around. Learn which notes go together in which orders and still sound good, and which don’t… even if you never intend to compose a tune, ever in your life, no matter what… it’ll still help train the ear, and prepare for learning different settings of tunes or learning tunes by ear… and, most importantly, it’s (to me, anyway) -more fun- than doing rote exercises. On the other hand if rote exercise are fun for you, well, go for it… some people find repetition like that relaxing, so, that’s cool if you’re that kind of person.
Anyway, I’ve always been able to play the whistle in my dreams, usually at about the ability I can play it in real life, or sometimes better. I’ve also found myself having dreams about taking whistles apart and studying the mouthpieces, inventing new whistle tunes, and so on. I’m sure if/when I build a whistle or two, I’ll have dreams about that too…
–ChrisA