| 8ve Oscillator
(Version 1.2 - January 2010)
Octave Oscillator with Noise produces test signals
(sine, square, pulse, triangular, sawtooth and white
noise) at a selection of octave spaced fundamental frequencies
(except the noise!) and arbitrary fundamental frequency
value entry across the usually quoted overall frequency
range of human hearing (20 Hz to 20 kHz) via a text
field.
As well as by text entry, the fundamental frequency
can be selected at the octave values for convenience
(going up or down by one octave doubles or halves the
frequency respectively) that are typically used for
acoustic testing of rooms, equipment testing and clinical
hearing tests: 125 Hz, 250 Hz, 500 Hz, 1 kHz, 2 kHz,
4 kHz and 8 kHz. The remaining available fundamental
frequency (16 kHz) is not used for acoustic or hearing
tests but it is an octave above 8 kHz and is close to
the frequency used for "mosquito" or "teen
scarer" devices; it is usually only audible to
those under 25 years.
The output level can be varied with a decibel (dB)
calibrated volume control arranged to allow the selection
of dB step value as 1 dB, 3 dB, 6 dB or 10 dB. These
enable the effect of stepping the output level in dB
to be experimented with: 1 dB is about the minimum step
size we can hear; a -3 dB (+3 dB) step is a halving
(doubling) in sound intensity; a -6 dB (+6 dB) step
is a halving (doubling) in sound pressure; and a -10
dB (+10 dB) step is a halving (doubling) in perceived
loudness.
Please be aware that listening to loud sounds can damage
your hearing. Please also bear in mind that if you cannot
hear a sound it does not mean that others around you
cannot hear it (everyone will lose high frequency hearing
with age - an effect known as presbycusus) - this is
especially true of the 16 kHz output which can be very
irritating to those who can hear it (this is why it
is used as a "teen scarer").
More details about human hearing can be found in: Howard
and Angus, Acoustics and psychoacoustics, 4th Edition,
Oxford: Focal Press, 2009, ISBN: 978-0-240-52175-6).
Please use Octave Oscillator with Noise with care and
due consideration for others.
Available NOW - click on
the App Store link below
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