Re: Writing a Symphony
Reply #29 –
G'day Al,
It isn't really that hard. The biggest problem is probably nomenclature.
For all practical purposes:
Overtones = Harmonics = Partials = Overblowing
Now, lets consider a Trumpet. The lowest "open" I.E. no valves down, note on a trumpet is a concert Bb just below middle C though the trumpeter will call it a C. For the purpose of this description we're also gonna call it a C. The note that the trumpet makes is defined by the length of the tubing. There are other factors involved but for the purpose of this explanation the length is the only consideration aside from the players lips.
This C is ctually the 2nd harmonic of the instruments "fundamental" frequency. The fundamental or 1st harmonic is the C an octave down and is usually only obtainable by players who have developed their emboucher somewhat... It is also commonly called a "pedal" C
The next note is the 3rd harmonic - a G
The next is the 4th harmoinic - the next C
Then you get E, G a sharp A and then C again
OK, so lets just "make a list":
Harmonic | Note |
1st | C |
2nd | C |
3rd | G |
4th | C |
5th | E |
6th | G |
7th | a slightly sharp A |
8th | "top" C |
This is considered a "normal" range - there are good trumpeters that can go way beyond "top C".
The same relationships hold when you use valve combinations for other notes. Depressing valves adds tubing to the length of the horn. the 1st valve adds enough tube for a change of 1 tone, the 2nd valve adds enough for a semitone and the 3rd valve adds enough for 3 semitones. With combinations of valves you get a full chromatic series from F# below "middle" C to as high as you can play. The only problem here is that when using combinations of valves you start getting sharp. I won't go into the reasons here as it is fairly complex.
These different harmonics are achieved by the player changing the tension in his/her lips and the air velocity - the faster you blow the easier is is to get higher notes 'cos your lips will vibrate faster more easily - you also get LOUDER. Good players can get very high notes without having to play excessively loud - in fact they can often play relatively quietly but it takes a good lip.
If you like, you can imagine that the players lips are like a rubber band - the more you stretch it the higher the note produced gets. All same the players lips when the muscle tension is increased.
The instrument will naturally support certain frequencies of vibration and not others - this is called "slotting". A good horn will "slot" closely to the correct harmonics and thus give good intonation. A very good horn will slot easily but still allow the player to "lip" up or down to create effects easily.
Poor horns don't slot well or slot off key.
As you can see from the table, the notes get closer. You reach a point up around the 11th or 12th harmonic where no valves are really required and all the notes can be "lipped" I.E. the "slots" dissapear. This is how Horns were originally played before they got valves.