To go on to the theoretical information.
Basics on Sound
These are just a few basic facts about sound behavior that will be used later in my
data and error analysis. Sound is a longitudinal wave, but it can be shown as a
lateral wave. This is accomplished by taking the harmonic spectrum, or a graph showing
the strength of each of each harmonic, and adding together the waves that each
harmonic will in itself produce when set in a displacement-time graph. Each of the
components will, in itself, produce a sine wave when set in this format, but when
added together will produce differant periodic waves.
Basics on Brass Sound Production
Brass instruments are "lip reed" wind instruments. That is they produce their
sound by the lips being placed against the end of the open pipe that makes up the
horn and vibrating. The fact that the lips are against an open end of the pipe will
make the pipe behave as a closed pipe. However, most brass instruments are conical,
and will therefore behave harmonically as an open pipe.
The mouth and throat have effect on the tone that is generated by the instrument,
even though it does not make sense at the first if you think of the lungs and throat
only as wind producers to make the lips vibrate. However, if you think of the lung-throat-mout
system as a "second 'brass instrument', with the air flowing in the 'wrong' direction"
(Campbell and Greated 325) then you can begin to see how
the waves might begin to interfere with each other, creating non-harmonic tones or
even canceling each other out.
How We Perceive Sound
This description will be basic simply because, although it is important for this
paper, all of the biological information is not necessary to understanding this paper.
We perceive sound because of vibrations in the inner ear. Pitch and timbre can be
assigned by the ear-brain system through the displacement of the basilar membrane located
inside the cochlea. We assign pitches to certain tones by hearing the relationships
between the different overtones and assigning the difference between their frequencies
as the root. For example, a complex tone with a root of 100 Hz will have overtones at 200, 300,
400, and 500 Hz. Our ear-brain system recognizes this as being at 100 Hz. However
we will still "hear" the root at 100 Hz even if a sound is electronically produced
that only contains tones at 300 Hz, 400 Hz, and 500 Hz. If one of these overtones
is slightly mistuned, say the 4th overtone is playing at 405 Hz rather than 400,
our ear-brain system will still determine the root to be at 100 Hz, but the pitch will
sound fuzzy or hazy. This is what I'm proposing is happening in a sound that has
poor tone quality. The harmonics are mistuned, thus our ear-brain system is having
trouble placing the pitch and it sounds poor as a result.
To go back to the background information.
Timbre is just another name for tone color. However, consider just how many
concepts are encompassed in timbre. An oboe sounds different than a flute, but a
beginning flute player sounds thin and airy compared to a seasoned veteran that has
been playing professionally for a couple of decades.
Timbre actually begins to encompass all three stages of a sound, those being:
In actuality what I tested can more precisely be termed "tone quality" as opposed
to timbre, as I am not interested so much in what makes a bad sounding trumpet sound
different than a bad sounding trombone, but rather what makes a single sound that is
the same as another in pitch, volume, and duration, played on the same instrument
and the same person different from another sound that simply is different
- Attack, or the way a pitch begins.
- The held or sustained portion of the pitch,
- Decay, or the way that a pitch ends.
Regardless of what it is termed, however, I was unable to find any answer to
my two predominant questions in any books that I searched. Thus my own extrapolation
will be found in the two following hypothetical sub-works that will begin to explore