10/06/2005

Sound Production

To play a note on trumpet I do not think about vibrating my lips. I like to think about blowing into the trumpet, and letting the vibrations that occur in the trumpet to cause my lips to vibrate sympathetically. How this works is that air focused into the trumpet causes what is called a standing wave inside the trumpet. This is what causes the trumpet to play, and our lips simply vibrate sympathetically with the standing wave in the trumpet. Students often look at me incredulously when I tell them this (I usually leave it at just "Let your lips vibrate with the trumpet", and don't go into a long physics explanation). I ran across a great post at by Mark Minasian at Trumpet Herald that explains the concept better than I ever did.
"You cannot blow a note out of the trumpet"... As I remember Mr. Adam's lectures, tests were done blowing smoke through trumpets, trombones and tubas. It took several seconds for the smoke to come out the bell, showing that one isn't blowing the note out of the horn. Also, if one were to take into consideration the speed of sound, 1130 ft/sec, the delay in the time it took for the sound to travel from lips to bell would be noticeable.

I saw John Harbaugh do a fascinating demonstration of trumpet acoustics. He took a clear pyrex cylinder and inserted a propane torch in one end. immediately a tone was produced, the tone having a wavelength equal to the length of the pipe. The flame obviously isn't buzzing or producing the pitch. The temperature differential between the flame and surrounding air creates vortices that provide the energy to excite the air in the tube and cause the production of the standing wave. Another interesting aspect of this experiment was that quickly AFTER the tone is heard, you can see the flame oscillating wildly in response to the standing wave. The sound comes first then the vibration of the flame. On the trumpet, do you buzz a note or do the lips buzz/vibrate in response to the standing wave?

I remember Mr. Adam often stating that the trumpet is static. It is a metal tube and unchanging. It is we who are dynamic and can change. If you try to muscle the horn to do your bidding you are engaged in a losing battle. We, as trumpet players, need to get "in phase" with the horn. This is one of the reasons for buzzing the leadpipe. The fundamental pitch of a mouthpiece by itself is around a high B or C. I can produce that fundamental pitch by blowing across the edge of the mouthpiece's stem, or backbore, in a manner like producing a tone on a coke bottle. Though buzzing the mouthpiece does have some pedagogical value, it can create unneccessary tension in a trumpet player as the player is trying to make each note with the lips rather than simply allow the horn to resonate on the given pitch.

By adding the leadpipe, you create a tube with a lengh long enough for a pitch approximately F in the treble staff. A much more comfortable place to start. than where the mouthpiece resonates. By producing a resonant buzz on the leadpipe, you "get in phase" with the instrument, adjusting to it's resistance, etc. Often, I will start by just blowing air through the mouthpiece then add the leadpipe, hearing the note speak as soon as the mouthpiece is engaged, or buzz the leadpipe then pull it away from the mouthpiece and listen to the non-buzzing but energized stream of air coming out the mouthpiece stem.

The bottom line is that we are using our air as the energizing force to get the horn to resonate freely.
Mark also posted something similar at TPIN where he gives another good example:
In a later clinic, trumpeter Charley Davis stated that he was part of a study where a miniature camera was mounted within a mouthpiece to record lip action. The activity observed with the flame could be seen in Charley's lips. They never touched or buzzed and the vibrating of the lips was a result of the standing wave generated within the horn.

I think that getting rid of the idea that the vibration comes from the lips is an important step towards playing with a rich, resonant sound. As a bonus, without fighting the horn you will find that playing is much easier, because in a fight the metal will always win.

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