Tremetrics RA660, Руководство по эксплуатации

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RA660 Operation Manual
8509790 Rev. 2 74 18/04/2018
L
LED Light-emitting diode
Level In acoustics The level of a
quantity is the logarithm of the ratio of
that quantity to a reference quantity of
the same kind. The base of the
logarithm, the reference quantity, and
the kind of level must be specified.
Examples of kinds of levels in common
use are sound power level, sound-
pressure-squared level, and sound
intensity level.
Loudness The subjective impression
of the power of a sound. During the
measurement loudness is understood
as loudness of a tone.
M
µ
“micro” = (10
-6
) = 0,000001
N
Noise level A level of noise, the type
of which must be indicated by further
modifier or context. The physical
quantity measured, the instrument
used, and the bandwidth or other
weighting
characteristic must be
indicated. For airborne sound, unless
specified to contrary, noise level is the
weighted sound pressure level, also
called sound level; the weighting must
be indicated.
Noise reduction (NR) A decrease
of the sound pressure level at a
specified
observation point.
Noise reduction is also used to
designate the differences in sound
pressure levels existing at two different
locations at a single time, when the
designated structures (such as baffles
or
partitions are in position.)
The term noise control is meaningful
only when noise control components
and the points of observation are fully
specified.
O

Ohm
Outer ear The outermost portion of
the hearing mechanism, filled with air.
Its primary function is to carry sounds to
the middle ear.
Oscar Electro-Acoustic Simulator
manufactured by TREMETRICS.
Oscillation The back-and-forth
swinging of a vibrating body.
P
PCB Printed circuit board
Percent impairment of hearing An
estimate of a person’s ability to hear. It
is usually based, as the result of an
arbitrary rule, on the pure tone
audiogram.
The specific rule for calculating percent
hearing loss varies from state to state.
Impairment refers specifically to a
person’s “illness or injury that affects his
personal efficiency in the activities of
daily living.” Disability has the additional
medico legal connotation that an
impairment reduces a person’s ability to
engage in gainful activity. Impairment is
only a contributing factor to the
disability. See also hearing loss.
Permanent threshold shift (PTS) The
component of threshold shift which
shows no progressive reduction with a
passage of time when apparent cause
has been removed.
Pitch The subjective impression of the
highness or lowness of a sound.
PN Part number
Presbycusis A decline in
hearing acuity that normally occurs with
the aging process.
Pulse Pulse stimulus consists of three
(3) short tones of 200 ms duration with a
rise and fall time between 20 and 50 ms.