I wasn't sure how to ask the question, but I'd like to know which of the
wind instruments can change pitch on a constant basis? To explain a little
better, a trumpet tone can be maintained and the pitch changed by sliding.
Thus, one goes throughout the different notes without pressing keys. Well,
how about the clarinet- can pitch be changed without changing keys?

Sorry, I'm a bit new with most musical instruments but I'm looking for winds
that can change pitch constantly for a special purpose.

Thanks,
Simon