11.3 Measured and displayed values
•
A, C or Z- weighted frequency acoustic pressure level and temporally weighted according time weightings : Slow, Fast or
Impulse. E.g. : LAF.
•
A, C or Z- weighted frequency maximum acoustic pressure level and temporally weighted according time weightings : Slow,
Fast or Impulse on a measurement time. E.g. :
LAFMax
•
A, C or Z- weighted frequency minimum acoustic pressure level and temporally weighted according time weightings : Slow,
Fast or Impulse on a measurement time. Ex :
LAFmin
•
C or Z weighted frequency peak pressure level. Ex
: LCpK
•
Equivalent continuous level of acoustic pressure, A, C or Z weighted frequency on a T time measurement.
Ex :
LAeq,T ou LAT
•
Equivalent continuous level of acoustic pressure, A, C or Z frequency weighted on a DI elementary measurement time. Ex :
LAeq,DI
•
Equivalent continuous maximum level of acoustic pressure, A, C or Z frequency weighted on DI elementary measurement
time met on the total measurement Ex :
LAeq,M
•
Equivalent continuous minimum level of acoustic pressure, A, C or Z frequency weighted on DI elementary measurement time
met on the total measurement Ex :
LAeq,m
•
Level of sound exposure A, C or Z frequency weighted on a T time measurement related to reference time of 1s. Ex :
LAE
Statistical indices :
Definition : When the sound level fluctuates, the distribution of the measured levels can be characterized by statistical indices. These
are statistically calculated from the time evolution of the sound level measured in-site. These levels correspond to X-weighted acoustic
pressure level which is exceeded for N% of the time interval. It is noted LN.
Therefore, the statistical indice L1 corresponds to sound level exceeded for 1% of the observation time, L50 for 50% of the time.
Calculated indices are :
L01 – L10 – L50 – L90 – L95
11.4
A – C – Z weightings and free field response
The frequency response of the whole
microphone / windscreen / A, C or Z weightings (sound level meter)
is in compliance with
standards in a given template according the accuracy class of the instrument :
NF EN 61672-1 / class 2
.
Plots types of free field sound level meter are given below :
Technical features
31
Free field response
with A weighting
Free field response
with C weighting
Free field response
with Z weighting
