A Music Study

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A Music Study

• Getting to Know the Pipe Organ and More

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What is sound?

• According to Dictionary.com, sound is vibrations
  transmitted through an elastic solid or a liquid
  or gas, with frequencies in the approximate range
  of 20 to 20,000 hertz, capable of being detected
  by human organs of hearing.

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What is sound?

• Another way of looking at is this Sound is any
  change in air pressure that our ears are able to
  detect and process. For our ears to detect it, a
  change in pressure has to be strong enough to
  move the eardrums in our ears. The more strongly
  the pressure changes, the "louder" we perceive
  the sound to be.

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What is sound?

• For our ears to be able to perceive a sound, the
  sound has to occur in a certain frequency range.
  For most people, the range of perceivable sounds
  falls between 20 Hertz (Hz, oscillations per
  second) and 15,000 Hz. We cannot hear sounds
  below 20 Hertz or above 15,000 Hertz. That is
  not the case with animals such as dogs.

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What does hertz (Hz) mean?

• Hertz or Hz is a unit of frequency equal to one
  cycle per second.
• 1 vibration / sec

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What is pitch?

• In music, pitch is the perception of the
  frequency of a note. For example, the A above
  middle C is nowadays set at 440 Hz (often written
  as "A 440 Hz", and known as concert pitch),
  although this has not always been the case. Pitch
  is often cited as one of the fundamental aspects
  of music.

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What is a tone?

• A tone is a sound that repeats at a certain
  specific frequency. For example, when somebody
  produces a note on an instrument, that note is a
  tone. Thus, notes and tones are said to be the
  same.
• Any note's frequency can be doubled to "go up an
  octave," and any note's frequency can be halved
  to "go down an octave."

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On to Pipe Organs

• One of the notable characteristics of the organ
  as a musical instrument is its ability to produce
  sounds of different timbre.

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On to Pipe Organs

• Quality of musical tone thin, thick, light,
  dark, sharp, dull, smooth, rough, warm, cold, etc.

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On to Pipe Organs

• Although there are indeed tone colors which are
  associated in most minds with the sound of an
  organ, the instrument can also produce many
  sounds that are imitative of other instruments.
  All of the different sounds of the organ are made
  by pipes - - often the most visible as well as
  audible part of the instrument. For the organist
  one of the challenges of the instrument is to
  learn about both the different timbres (tone
  colors) available and the names of the "stops"
  that produce those sounds.

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Pipe Organs Continued

• In general we use the term "stop" to refer to a
  method of controlling which pipes speak when keys
  are played. We also use the term in a more
  specific way, when we refer to the actual control
  itself -- usually a drawknob or a stop key -- as
  a "stop." The context in which the word is used
  can usually clarify what is referred to at the
  time -- the sound or the control for that sound.
  To make matters more complicated, there are two
  sub-types of stops that a student will encounter.

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Pipe Organs Continued

• Half stops control a short register -- one that
  does not extend the full compass of the keyboard.
  In most applications -- a Cornet V, for example
  -- the stop will sound only in the upper octaves
  of the keyboard, often beginning on c1. Many
  instruments built in the last quarter of the
  twentieth century have such a stop on the Great
  division.

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Pipe Organs Continued

• Divided stops provide two stops for a single
  register or rank of pipes. One stop controls the
  lower octaves of a keyboard, the other the upper
  octaves. This arrangement is most often found on
  very small instruments, where the player might
  want to play one timbre in the left hand and a
  different one in the right hand, but only one
  manual is available.

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Pipes

• Flue pipes (usually called simply "flues") have
  no moving parts. Their sound is produced when a
  stream of air is focused onto a sharp edge - -
  the upper lip of a flue pipe. As the wind strikes
  the lip, its smooth flow is disturbed. In the
  resulting disturbance, a vibration is set up in
  the air column contained in the pipe body,
  producing an audible sound wave. A similar
  structure and result can be seen in the mouth of
  a recorder, which produces its sounds in the same
  way.
• Flue pipes have two primary parts, the foot and
  the body. Although these names are used for both
  metal and wooden flues, there are other
  differences in their construction, according to
  the material being used.

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Metal Pipes

• The body of metal flues is typically circular in
  horizontal cross section, and it may be either
  cylindrical or conical in shape. The top of the
  body may be either open, closed or partially
  closed.

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Metal Pipes

• When the pipe is open, the end may be treated in
  one of several ways. The first method is to cut
  the pipe to the correct length to obtain the
  desired pitch. Because changes in temperature and
  the density of the surrounding air can have an
  effect on pitch, these pipes may be altered
  slightly by having the edges turned slightly out,
  or slightly in to modify the pitch. This approach
  to pitch modification is called coning or cone
  tuning, and must be done very carefully. The
  photograph shows two pipes from a 2' Principal
  that have been coned in opposite ways.

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Metal Pipes

• The second treatment for the top of a flue pipe
  is to fit the open end with a movable sleeve or
  collar of metal. The collar is not fastened to
  the body of the pipe, but is held tightly in
  place by tension, leaving it free to be moved up
  or down to affect pitch changes. Even when the
  pipe is made of spotted metal, a thinner, less
  malleable sheet of metal is used for the collar,
  as seen in this photograph.

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Metal Pipes

• Finally, open pipes may have two small cuts made
  into the material of the body at the open end.
  The metal between the cuts may be rolled down to
  shorten the effective length of the body, as seen
  in the photograph to the right. 13 The resulting
  curl of metal is usually called the "scroll," and
  the process of tuning a pipe in this manner is
  referred to as "scroll tuning" or "scrolling."
  Alternately a separate, movable piece of metal
  can be fastened to the body of the pipe. This can
  then be moved up or down to make a similar
  change.

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Metal Pipes

• In metal pipes the foot is usually conical and
  expands from a small base to the point at which
  it joins the body. An inset plane around the
  joint between foot and body is called the face,
  and an opening into the pipe - - the mouth - - is
  cut into the pipe on that plane above the
  languid, an internal horizontal plate that almost
  completely closes off the foot from the body.

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Metal Pipes

• A harmonic bridge, commonly called a beard, is a
  horizontal plate attached below the lower lip, or
  a wooden dowel placed between the ears. The
  photograph to the left shows a pipe mouth with
  ears and a wooden bridge.

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Wooden Pipes

• Wooden Flue Pipes
• The choice of materials has an effect on the
  shape a pipe assumes, and wooden pipes are most
  often square or rectangular in horizontal cross
  section. As the photograph to the left shows,
  even wooden pipes usually have a cylindrical
  extension at their base, and that extension will
  often terminate in a lead tip which allows the
  toe hole to be opened or closed without damage to
  the wood.

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Wooden Pipes

• Two exceptions to wooden pipes having a
  rectangular shape are noteworthy
• The Triangle Flute, as made by E. M. Skinner in
  the first half of the twentieth century, and
  continued in organs by the Aeolian-Skinner Organ
  Company, have a triangular cross section.
• The Organ in the Mormon Tabernacle in Salt Lake
  City has round wooden pipes in the façade. The
  pipes are plated with gold leaf.

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Wooden Flue Pipes
The body of a wooden flue may be either open,
closed or partially closed, but the construction
of the upper end of wooden pipe bodies
isdifferent from that found in metal pipes.
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Wooden Flue Pipes
Closed wooden bodies are usually fitted with a
stopper made of wood and padded with leather. The
stopper is made to fit inside the body and
usually has a handle, or even a cord, attached to
its top so that its depth can be adjusted. The
photograph shows a typical stopped pipe with a
stopper from another pipe beside it.
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Wooden Flue Pipes
Partially closed wooden pipes are made in several
different ways. The most common way is found when
a piece of metal is attached to one side of the
top of a wooden body. The flap of metal is then
rolled back, or scrolled, to partially uncover
the top of the pipe
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Wooden Flue Pipes
The mouths of wooden pipes are generally built as
a part of the body.
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Reed Pipes (Reeds)
Just as flues have two primary elements in their
construction, reed pipes (usually called simply
reeds) have both lower and upper parts, in this
case called boot and resonator respectively.
However, reeds differ from flues both in the
timbre of their sound and in the way that sound
is produced. The chief difference lies in the
presence of a vibrating body - - the tongue - -
in reeds. Flues produce sound through the
creation of turbulence in a stream of wind, and
that turbulence resonates in the body. In a reed,
however, there is actually a part of the pipe
that vibrates to produce the sound.
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Reeds
Reed resonators are usually made of metal,
although wooden resonators may be found. Metal
resonators may be found in a variety of shapes,
but they are usually circular in horizontal cross
section. The photograph to the left shows the
three most common shapes for resonators. Cylindric
al resonators may be open or partially closed, as
in this photograph.
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Reeds
Conical resonators are most often open the angle
of the cone - - how much its width increases for
each unit of length - - may vary. Combinations
of cylindrical, conical, or inverted cones may
also be found. When resonators are made of wood,
they most often are square in horizontal cross
section. In an approximation of the cylindrical
and conical shapes of metal resonators, they may
be built with near parallel sides, or they may be
flared outward as they extend from the boot.
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Reeds
Organ pipes are usually placed in an upright
position, but one exception should be noted. Some
trumpet stops are placed in a horizontal
position, so that the top end of their resonators
actually face the listener. Reed stops placed in
this manner are usually called en chamade reeds,
and their appearance can be quite striking.
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So Much to Learn

• This slide show should have provided you with an
  introduction to the pipe organ. Tomorrow, we
  will actually see one in action.