Singing this Note is IMPOSSIBLE!

That's why trumpets, horns... have valves, or trombones have a slide. These play a completely different role from the keys in woodwinds : for woodwinds, opening/shuting the holes give the possibility to lock the exact note, but for brass, opening/shuting valves or sliding the trombone do not makes the note, but simply changes the playable notes interval in the tube. For both, the note is made in the mouth, i.e. in the resonant cavity made of the chicks, the tongue and the mouthpiece. In the case of brass, the vibrating part are the lips, and in the case of woodwinds, the vibrating element is a wooden blade.


 In both cases the tube by itself adapts the acoustic impedence of the resonating system formed by the vibrating device and the cavity. Of course, this is true only if you don't try to play a note outside the "playable" interval (i.e. under or at resonance). That's the role of the valves on brass : as long as you want to play notes inside the playable interval for your tube, you don't need to change it's length. If you have to play outside, you've got to change the lenght : in a trombone you do it 'by hand', in a trumpet, you select a pre-determined tube lenght among a set of possible values...


Woodwinds offer both types of playing : fixed tube length, and sliding the notes "with the mouth", or just rely on the resonance of the tube length to lock the notes, using the keys... and the saxophone is a brass adapted to both types of playing !!