WHICH PITCH: How Do We Know?
Kudu horns
(side-blown
trumpets) from
South Africa
Musical Instrument Museum (MIM)
Electric guitar
from USA
Gong from
Thailand
Sikuras (raft flutes)
from Chile
Taiko (double-headed
barrel drum) from USA
Morin khuur
(bowed spike lute)
from Mongolia
Making Sound: What’s Vibrating?
Aerophone (clarín, quena, sikus)
– the air inside the instrument vibrates.
Chordophone (charango, harp, violin, morin khuur)
– the strings vibrate.
Idiophone (triangle, ketuk, slit drum)
– the instrument itself vibrates.
Membranophones (djembe, goombay, bongos)
– the membrane vibrates when struck.
Pitch: Intersecting Music and Science
Musically speaking, pitch is defined as the location of
a note, depending on its highness or lowness.
Scientifically speaking, pitch is an aurally perceived
property of a sound, especially a musical tone, that is
determined by the frequency of the waves producing
it: the highness or lowness of sound.
The Long and Short of It: Chordophones
Can you predict the pitch
of a stringed instrument
(chordophone)
by looking at it?
How does string
length play a part?
Guitar and
double-bass
from
Argentina
Morin khuur
from
Mongolia
For Strings
The longer the string, the lower the
fundamental frequency and the pitch.
The thickness, tightness, and material of
the string also matter!
Violin from Germany
Nyckelharpa (bowed lute) from Sweden
Aerophones
Is there a similar correlation among pipe instruments,
for instance, aerophones such as a trumpet or a tuba?
What About Other Pipe Instruments?
Organ Pipes
Portative pipe
organ from Peru
Pipe organ from
USA
What About Other Wind Instruments?
Musical jug
from USA
Rondador (raft flutes) from Ecuador
Over-the-shoulder horns (valved horns) from USA
Types of Pipes: Open and Closed
Open ended pipes: both ends are open organ pipes
Closed ended pipes: one end is closed musical jug,
trumpet, raft flutes
At the correct frequency, the air column resonates
(we’ll get to resonance in a bit).
Open Ended Pipes


At the open end, air
molecules can move a lot
– In the drawings, you see
the curves far apart where
the air moves a lot; those
positions are called
antinodes
In between the antinodes,
there are places where the
molecules don’t move much;
those positions are called
nodes.
Closed Ended Pipes


At the closed end, molecules
don’t move much.
– Nodes exists at the closed
end, antinodes at the
open end.
The nodes are farther apart
than in an open pipe, so the
wavelength is longer and
the pitch is lower than for
an open pipe.
Wavelength and Pitch


The closer the nodes are to
each other, the shorter the
wavelength of the wave,
measured in meters.
The top drawing shows the
longest wavelength; the
bottom one represents the
shortest wavelength.
Frequency and Sound
Frequency (f) is the number of vibrations made each
second and is measured in Hertz (Hz).
For sound waves, the pitch corresponds to the
frequency of the sound wave.
Higher frequencies of sound waves are interpreted by
our brains as higher pitches.
Wavelength and Frequency
Wavelength and frequency are inversely related, so
the larger the wavelength, the smaller the frequency.
Wavelength and Frequency
Longer pipes have longer wavelengths.
Longer wavelengths have
lower frequencies.
Lower frequencies
create lower pitches.
That’s why the longer raft
pipes have a lower pitch!
Sikuras (raft flutes) from Chile
What do you know?
The
of the pipe affects the pitch in wind
instruments such as the panpipe.
Frequency (f) is the number of
second and is measured in Hertz (Hz).
made each
For sound waves, the pitch corresponds to the
of the sound wave.
Higher frequencies of sound waves are interpreted by
our brains as
pitches.
Want to Know More?
In other lessons, you can investigate the relationship
between frequency and pipe length as you make your
own panpipes.
Sikus (raft flutes) from Peru