Horn 01: Overtone Series

The horn is basically a very long metal tube wound up on itself for convenience. Before the invention of valves the only way to produce different notes was by changing the pressure of the lips, the embouchure.

Here is the rubber hose version:

However, not all notes were available; only those of the overtone series (also known as the harmonic series) could be sounded. The instrument’s fundamental note was determined by the length of the tubing with the overtone series based upon that fundamental note.

Different sized crooks were invented that could be inserted into the horn to lengthen the tubing thus giving a new fundamental with a new series. However the instrument was still limited to the same set of possibilities.

Natural Horn with four crooks (from http://www.auburn.edu/~schafwr/naturalhorn.html)

The same applies to the natural trumpet. Even the trombone produces notes the same way except that instead of having to stop playing for a few seconds to insert a new crook the player can extend the slide out, effectively lengthening the tube. Otherwise all notes are produced by lip pressure.

from www.ceciliomusic.com

Hornists could “bend’ pitches by inserting their hands into the bell of the instrument, noticeably changing the tone in the process. These hand stopped notes enlarged the pitch possibilities but nevertheless could only be produced by modifying the one available overtone series.

The “squeezed” sounding notes in this video are hand stopped notes:

When valves were invented for the horn and trumpet nearly 200 years ago the principle remained the same; now the tubing is lengthened by depressing a valve which opens up a new bit of tubing. However, if a player remains on any one valve combination only the overtone series of that particular fundamental is available.

Horn (valved)

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String players have harmonics at equal divisions of the string (half way, quarter way, one fifth, two fifths, etc). Those harmonics are the overtone series. Woodwind players overblow (sometimes with the help of a special key) at the octave which means they finger the fundamental and with lip pressure produce the second overtone; except the clarinet which because of its design produces the third overtone, but it still dependent on the series.

There are some guitar harmonics at the beginning of this clip:

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The overtone series is fundamental to all sound and most music. A composer can’t really get away from it; it can be worked against and ignored as much of the 20th century’s serial music has done but it is still the DNA of each individual note. (A fun introduction to 12-tone music is here). It is the reason that well-tuned pianos and synthesizers are, in fact, out of tune…but that’s another topic and probably outside the scope of this blog.

It is also what’s going on with Tibetan chanting and then there is this: