HD2010UC
- 107 -
V4.2
The non-weighted peak level and the IMPULSE level relevant to the surface mount machine
are illustrated in the figure. As you can see, the peak level is at least 10 dB higher than the
IMPULSE level. The parameter “PEAK”, referred to as L
pk
has been defined in the international
standards (IEC 60651/IEC 61672). It provides the peak level reached by the sound pressure in a
given time interval. The response time of the peak level is ver
y fast (<100μs) and it is able to meas-
ure the sound level of very short sound events (for example, a gun shot) with sufficient accuracy.
E
QUIVALENT
S
OUND
P
RESSURE
L
EVEL
The approximation obtained by considering the levels with FAST or SLOW time constant as
short-term averages is quite rough. If the sound during its propagation transports energy, it is im-
portant to account for the duration of the sound event in order to interpret the energy content cor-
rectly.
This is particularly important in assessing the impact of the sound produced by machines or
general pollution sources on the auditory apparatus. It is obvious that a strong noise generates a
growing damage proportional to exposure. Evaluation of potentially harmful noise is therefore easy
with constant level sounds.
If the sound varies in time you have to use a measurement parameter, defined in the interna-
tional standards (IEC 60804, recently replaced by IEC 61672), called “equivalent level”, symbol
L
eq
. The equivalent level is defined as the constant level having the same energy content of the fluc-
tuating level in the period being examined. The A weighted equivalent level (L
Aeq
) will be used to
measure the energy content, and then the harmful potential, of a fluctuating noise source during a
given period.
Summary of Contents for DeltaOHM HD2010UC
Page 2: ...HD2010UC 2 V4 2 ...
Page 129: ...HD2010UC 129 V4 2 NOTES ...
Page 130: ...HD2010UC 130 V4 2 NOTES ...
Page 131: ......