Everything about Free Reed Aerophone totally explained
A
free reed aerophone is a
musical instrument where
sound is produced as air flows past a
vibrating reed in a frame. Air pressure is typically generated by
breath or with a
bellows.
Operation
The following illustrations depict the type of reed typical of
harmonicas,
pitch pipes,
accordions and
reed organs as it goes through a cycle of vibration. One side of the reed frame is omitted from the images for clarity; in actuality, the frame surrounds the reed on four sides and cuts the space in an upper and under reed area.
As soon in the area under the reed a negative pressure is created, the reed will start to move.
See at
Bernoulli's principle for entire explanation.
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A reed is fixed by one end in a close-fitting frame. The loose end has a slight rising bend. |
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Air depression is applied under the reed; the reed prevents air flow, except for a small, high-velocity flow at the tip. |
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The reed is sucked through the opening, allowing the air to pass. |
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The elasticity of the reed forces it back through the frame. |
Each time the reed passes through the frame, it interrupts air flow. These rapid,
periodic interruptions of the air flow create the audible vibrations perceived by the listener.
In a free-reed instrument, it's the physical characteristics of the reed itself, such as mass, length, cross-sectional area, and stiffness, which primarily determine the pitch (
frequency) of the musical note produced. Of secondary importance to the pitch are the physical dimensions of the chamber in which the reed is fitted, and of the air flow.
History
The most likely precursor to free reed aerophones is the
Jew's harp, an instrument known to many cultures throughout the world, and by many names. In this instrument, the main sound producer is the vibrating reed tongue itself, rather than the air flow.
Various free reed instruments appear to have been invented since antiquity, but were unknown in the West until comparatively recently. Among the ancient instruments, the
Khene of
Laos and the
Sheng of
China have survived to modern times. It has been claimed that the Sheng was brought to
Saint Petersburg,
Russia near the end of the
18th century, inspiring a series of inventions in the early
19th century that were the foundation of the development of the modern free reeds; Cyrill Demian's
(see below) patent of 1829 however states that the reeds in his instrument "were known for more than 200 years as Regale, Zungen, Schnarrwerk, in organs."
Some notable early modern free reed instruments:
Other examples
The harmonica.
The harmonium.
The melodica.
The bandoneón.
Related instruments
In the related woodwind instruments, a vibrating reed is used to set a column of air in vibration within the instrument. In such instruments, the pitch is primarily determined by the effective length of that column of air.
Further Information
Get more info on 'Free Reed Aerophone'.
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