How do you make different notes on the french horn?

Answer 1

A musical note on any wind instrument is produced by a vibrating column of air inside a tube. Change the length of the vibrating column, and you change the note.

There are different ways of changing the length of the tube:

1) Make the tube shorter by opening holes in it (what most woodwinds do).

2) Make the tube longer by sliding out an extension (what the Trombone does) or opening a valve that re-routes the air through an extra piece of tubing (what the rest of the brass do).

3) Make the vibrating column inside the tube shorter by forcing it to kind of separate the air column into segments (e.g. dividing the air column into two segments, 2:1, makes an octave higher). The segmentations are predictable according to the harmonic series. Most woodwinds overblow at the first harmonic, the octave; most brass do several more harmonics above that (the horn tends to play very high on the harmonic series relative to the other brass, which makes it perhaps the most difficult to play). On a brass instrument such as horn, you buzz your lips at the right frequency to lock in the desired harmonic.

The horn uses the 2nd and 3rd of these, but adds another unique method. By placing the hand into the bell, the player can micro-adjust the length of the air column and thus change the pitch. Before the invention of valves, in fact, the "natural horn" was played using only harmonics and hand-stopping; the wonderful horn concertos of Mozart, and even Brahms's op. 40 horn trio, were written for these instruments. Even after the invention of valves, horn players continue to use the hand in the bell to shape the pitch and tone color.