GoodSoundClub - Romy the Cat's Audio Site

In the Forum: Playback Listening
In the Thread: Audio vs. Musical pitch

Post Subject: 6 TrumpetsPosted by rowuk on: 5/1/2013

Well, as I do play trumpets professionally and own much more than 6 instruments, I thought that I would chime in.

First of all, Romy, this is one of the most lucid descriptions of pitch that I have ever read! It also raises a point for discussion:
If I play a concert A in the staff the perceived pitch is 440Hz (443 in Germany, 415 if we are playing standard historically informed baroque music). The fundamental on the trumpet is an octave lower. We hear the first harmonic as it is MUCH stronger (look at the size of a trumpet bell and you know why 220Hz, the fundamental is so much softer......). The rest of the harmonics are balanced slightly different based on the instrument and player. What my point is, when we play concert A in the staff a percentage of the sound is reproduced by the speaker responsible for the 220Hz fundamental, perhaps another speaker for the first overtones: 440 (2x fundamental), 660 (3x) and 880Hz (4x), a third for some higher overtones 1100 (5x), 1320(6x), 1540(7x) and so forth. That means that depending on the note that I play, the reproduced structure can vary a great deal depending on which speakers are used and their phase relationship. If I play A above the staff in as my example above, the lowest speaker is no longer involved in the reproduction of my "pitch". If the microphone used in the recording is close to the trumpet, we have a much different tone balance than if it is further away.

In music we have additional issues. When two instruments play different notes at the same time, sum and difference tones are created. I guess this could be called acoustical intermodulation. In any case, it is often a desired trait and many brass sections go as far as to match the instruments to maximize the effect! This accounts for a lot of the brass section sound and essentially spreads the required frequencies over an even larger range. 440Hz(A) and 660Hz(E) as pure tones without harmonics create 220 and 1100 Hz as audible sum and difference tones. Strong overtones also produce audible "sideband" frequencies further increasing the frequency response, phase, and spatial demands - even if only two instruments are playing. Major chords create sidebands that are harmonically related to the chord - there is little dissonance. Minor chords create sidebands that are NOT harmonically related. This creates additional "drama" or "tension".

On a side note, I teach trumpet and "weak" players often "sound" sharp - even if a tuning device "proves" that their tone is centered at the correct pitch. I use acoustical intermodulation to teach my students how to tune relative to whatever group or player is considered "dominant".

On a second note: in a symphony orchestra the oboe gives the tuning note. This has to do with the overtone structure that makes that instrument very easy to understand "pitchwise".

Their is an excellent treatise on intonation written by a former horn player of the Chicago Symphony Orchestra. I strongly recommend it for anyone that really has any interest in "pitch":

http://www.cherryclassics.com/cherry/leuba-chris-study-musical-intonation-chris-leuba-former-principal-horn-the-chicago-symphony-method-book-for-brass-instruments-p-2128.html

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