The power spectrum of each
sample had the expected shape, with the maximum spike at the fundamental
frequency and smaller spikes at the overtones. I took data both close
to the microphone and further away. Figure
11 is the power spectrum of an A at 880 Hz with player 1 on flute A
only about 5 inches from the microphone. The y-axis is normalized
by the maximum spike which occurs at 2f, 2640 Hz (E). If this E were
the prominent frequency, a listener would most likely hear an E instead
of an A at 880 Hz. Figure 9 is the same
note played at a distance (9 feet) from the microphone. The power
spectrum shows the maximum peak at the fundamental frequency, 880 Hz, which
is what the listener hears. In order to analyze the same frequencies
that a listener hears, all of the following data was taken as a point source,
approximately 9 feet from the microphone.
I took all of my data
without vibrato. Vibrato is a pulse created in the sound by the player.
The pulse causes the frequencies to oscillate around the actual value.
Figure 12 is an A at 440 Hz played by player
1 on flute A without vibrato. In Figure 13,
player 1 used vibrato. The spikes appear at the same frequencies
in each graph. However, as shown in Figures
14 and 15, close-ups of the overtone with maximum relative amplitude
(2f or 1320 Hz), the spikes in the note with vibrato are thicker.
This is due to the oscillations around the frequency.
The higher notes (higher
frequencies) have a smaller harmonic series on a power spectrum than the
lower notes. Figures 3, 9, and 10
are power spectra for three different octaves of A, 440 Hz, 880 Hz, and
1760 Hz, respectively, all played by player 1 on flute A. Figure
9 shows that player 1 only has 2 overtones for 880 Hz. The first
overtone, 2f, is 1760 Hz (A), and has a high relative amplitude.
This spike is an average of 20% of the fundamental frequency. The
spike at 3f, 2640 Hz (E) is very small (less than 1% of the fundamental).
Figure 10 shows that for an A at 1760 Hz, which
is the third octave A on a flute, there really is no harmonic series present.
There is a very tiny spike at 3520 Hz, an octave above, but it is much
less than 1% of the fundamental.
I also compared the power spectra
of 4 different octaves of the note B, 247 Hz, 494 Hz, 988 Hz, and 1976
Hz. Figures 16, 17,
18,
and 19 show these plots, respectively.
247 Hz is the lowest note that a flute with a B foot joint can play.
As seen in these graphs, the lower notes have more overtones from the harmonic
series than do the higher notes. This is the same pattern that was
seen in the different octaves of A.
The amplitudes and the number
of overtones that appear vary depending on the player and on the flute.
A comparison of the power spectra of three different players all playing
the same note on the same flute shows that the player has a greater effect
over the frequencies produced by the flute than any characteristic of the
instrument. To be consistent, I used A at 440 Hz for the comparisons
between flutists and between flutes. As seen in Figure
3, player 1 produces the first 4 overtones of the harmonic series of
A at 440 Hz. The overtone with the greatest relative amplitude compared
to the fundamental is 3f (2200 Hz), which is an E. As shown in Figure
4, Player 2 creates the first 5 overtones with the relative amplitudes
decreasing with each subsequent overtone. Player 3 produces the first
6 overtones, as seen in Figure 5. In this
plot, the spike at 3f has a very high relative amplitude compared to the
fundamental, such that in some of the samples, it is actually almost equal
to the fundamental. Figure 21 shows the
average relative percentages for each overtone of the fundamental frequency
for the three players on flute A. For the frequency values and corresponding
notes of each overtone, see Table 1.
The previous comparison showed
that the player has a greater effect on the power spectrum of a note than
does the flute. The next comparison is player 1 playing an A at 440
Hz on flutes A, B, C, and D. Figure 3 is
player 1 on flute A, as described in the previous comparison. Figure
6 shows the power spectrum for player 1 on flute B. The overtones
in this plot have similar relative amplitudes compared to Figure 3.
Figure
7 shows the power spectrum of player 1 on flute C. The relative
amplitudes decrease as the frequency increases.
Figure
8 is the power spectrum of player 1 on flute D. The overtones
in this plot have low relative amplitudes. Player 1 seems to always
create only four overtones, except on flute D, where 6f has a very small
peak. Figure 22 shows the average relative
percentages for each overtone of the fundamental frequency for player 1
on the four different flutes.
As seen in the previous data,
the flute player has a greater effect on the resulting harmonic series
for each note, than does the instrument. The greatest uncertainty
in the frequency measurements for each note is due to the human factor.
Each player can change the resulting frequencies by changing her embouchure,
how much air she uses, and any other factor that is part of playing a wind
instrument.
Abstract
Introduction
Experimental Setup
Results
Discussion
Conclusions
References