Actually I was just about to ask about vowel sounds. Does it change the colour of a pitch very much if a trombonist (and this is the instrument I'm really interested in here) is making a different vowel sound, or does this affect the pitch too...
Would be interested to know about this on the recorder too.
I've been away so apols for late contribution but hope this is useful?
HH:Yep- Berio's Sequenza 5 makes great use of this. In a more subtle way
it crops in jazz technique of course, but the use of the plunger mute-maleable like apair of large rubbery lips-to
distort the sound at the production end is far more effective. 'Tricky' Sam Nanton probably the master here, conjuring all manner of garrulousness, possibly also Steve Turre recently(who also incorporates blown conch shells as vocal effects).
Autoharp re: baritone: euphonium, I think you're right to say that they have differing performing traditions but I think I'm right in saying that they fulfill paralell functions in the military: concert band set-up.
Richard, a useful place to explore these matters could be the Horniman Museum in Forest Hill where many of the historic saxhorns and tubas are still playable.They have some archived recordings I think ,and you used to be able to arrange to try things outby appointment.