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Loudness
Loudness is the subjective judgement of intensity of a sound by humans. Loudness depends upon
the sound pressure and frequency of the stimulus and whether the sound field is diffuse- or free-
field. The unit is the Sone. The Zwicker method of calculation of stationary loudness based on 1/3-
octave measurements is described in ISO 532 - 1975, Method B.
Loudness
Level
Loudness Level = 10*log2(Loudness) + 40. The unit is the phone.
Overload
When the broadband sound level is about the measuring range of the instrument. The light ring will
flash red.
Peak
Maximum peak of the acceleration, velocity, displacement signal or voltage input with frequency
weighting Linear.
Peak-peak
The real peak-to-peak value (difference between the most positive value of the signal and the most
negative value of the signal). Available for Displacement only.
Slow Max
Maximum time-weighted acceleration, velocity, displacement or voltage level measured with Linear
frequency weighting and Slow time weighting. It is the highest level occurring during the meas-
urement time.
Slow Min
Minimum time-weighted acceleration, velocity, displacement or voltage level measured with Linear
frequency weighting and Slow time weighting. It is the lowest level occurring during the meas-
urement time.
Sound
Any pressure variation that the human ear can detect. Just like dominoes, a wave motion is set off
when an element sets the nearest particle of air into motion. This motion gradually spreads to adja-
cent air particles further away from the source. Depending on the medium, sound extends and
affects a greater area (propagates) at different speeds. In air, sound propagates at a speed of approx-
imately 340 m/s. In liquids and solids, the propagation velocity is greater - 1500 m/s in water and
5000 m/s in steel.
Sound level
or sound
pressure
level
The level in decibels of the pressure variation of a sound. See also decibel.
TCpeak The time when the peak sound level occurred. ‘C’ denotes that the C frequency weighting is used.
Underrange
When the broadband sound level is below the measuring range of the instrument. Underrange is
only indicated on the screen;no underrange information is saved with the final result of the meas-
urement.
Z-weighting
‘Zero’ frequency weighting is without any frequency weighting, that is, equivalent to Linear, LIN or
FLAT.
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