Edelmann Galton Whistle
The Galton whistle, invented by Sir Frances Galton
(1822-1911), was one of the earliest devices used in testing hearing. M.
T. Edelmann improved the Galton whistle in 1900. It is now known as the
Edelmann Galton whistle.
It
was used in the first quarter of the 20th century, but was later
abandoned when better instruments were introduced, including the
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Front view of the Edelmann Galton whistle. With the micrometers
srcewed to their maximum positions the Edelmann Galton whistle measured
6 15/16" (17.5 cm), and with the micrometers both screwed all the way
in, it measured 5 13/16" (14.7 cm).
It weighed a hefty 6.8 oz. (198 g).
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Rear view of the Edelmann Galton whistle.
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View of the middle of the body of the Edelmann Galton whistle showing
the manufacturer's name (Edelmann) and below that, the manufacturer's
location (München) or in English (Munich) in Germany. The serial
number is on the left side (628).
Note the number "13" stamped into the top of the body (center). This
same number is stamped into the left vernier part—probably indicating
that they are a matched pair and made to go together. |
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Close-up view of the left end of the Edelmann Galton whistle showing the
number 13 here as well as on the body (above).
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Close-up view of the left end of the Edelmann Galton whistle showing the
micrometer at its minimum (0) position (high-frequency setting). You
adjust the frequency by unscrewing the micrometer through a scale of 0
to 25 with 25 being the lowest frequency.
Tables that came with the Edelmann Galton whistle gave the settings
of both micrometers and the air pressure required to produce a given
frequency of sound. (These tables are missing.)
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Close-up view of the left end of the Edelmann Galton whistle showing the
micrometer at its maximum (25) position (low frequency setting).
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Close-up view of the left end of the Edelmann Galton whistle with the
calibration unit totally unscrewed showing the piston (bottom).
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Diagram of a Galton whistle showing the piston (right)—the left side of
the Galton whistle (shown above), and the air flow from the right side
of the Galton Whistle (shown below).
(Taken from
Section 3.1 Gas-driven Transducers.)
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Close-up view of the right end of the Edelmann Galton whistle showing
the nozzle
where the rubber air hose was pushed on. Note: you can also blow into
the nozzle, but with an air hose attached you could get constant air
pressure which gave a sustained sound
at a constant volume. This made the Edelmann Galton whistle useful for clinical
hearing testing.
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View of the right end of the Edelmann Galton whistle showing
the nozzle screwed off.
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Close-up view of the "sound gap" in the center of the Edelmann Galton
whistle shown with the minimum gap (a bit less than 1 mm). To use the
Edelmann Galton whistle, air is blown into the nozzle at the right end and emerges
from a circular slit (center right) to fall on the knife edge (center
left). The size of the chamber to the left of the knife can be controlled by the
piston in the left micrometer. The frequency of the sound emitted depends
on the size of the chamber to the left of the knife edge and the pressure at
which the air enters the nozzle.
Frequencies as high as 100 kHz were obtained with this device.
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Close-up view of the "sound gap" in the center of the Edelmann Galton
whistle shown with the maximum gap (approximately 3.5 mm).
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View of the right micrometer of the Edelmann Galton whistle shown in its
minimum position.
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View of the right micrometer of the Edelmann Galton whistle shown in its
maximum position.
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Close-up view of the left end of the Edelmann Galton whistle.
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View of the Edelmann Galton whistle in its original case. Note that the
nozzle at the
right end of the whistle sticks through the end of the case.
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Close-up view of the bottom left corner of the Edelmann Galton whistle
case showing the name plate there. The name plate reads "C. H.
Stoelting Co." then "Scientific Apparatus" with the Stoelting logo
between the words, and at the bottom "Chicago. Ill. This plate
was added by the USA distributor of the Edelmann Galton whistle. |
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Outside view of the original case of the Edelmann Galton whistle.
The case measured 6½" x 2 7/16" x 1 5/16" (16.5 x 6.2 x 3.3 cm).
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Close-up view of the bottom left corner of the Edelmann Galton whistle
case showing the words "Galton - Pfeife". Pfeife is the German word for
the English word "fife" (whistle).
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Close-up view of the bottom right corner of the Edelmann Galton whistle
case showing the manufacturer's name (Edelmann) and location (München or
Munich) in Germany.
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Close-up view of the right end of the Edelmann Galton whistle case
showing the right end of the whistle sticking through.
The reason for this was that a rubber air hose was pushed onto the
nozzle at this end
of the whistle and wouldn't be the easiest thing to remove each time
this whistle was used. Therefore, the case was designed to allow the
whistle to be "put away" to keep it clean while the air hose was still
attached.
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