SW-BA-e-2020
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7.5 Technical data of the 1/1 octave filter
The 1/1 octave filter was developed from a Butterworth filter with base 10. The
technical specifications of each filter are shown in the figure below.
7.6 Glossary
⚫
Frequency weighting
1
: The difference as a function of frequency between the
level of the frequency weighted signal on the display unit and the corresponding
level of a constant sinusoidal input signal. The difference in level is expressed in
decibels (dB). Frequency weighting usually involves A, B, C and D weighting,
which can simulate the frequency response of the human ear. The A and C
weighting are more commonly used and are defined in the IEC standard and GB/T
standard. The B weighting is only defined in the ANSI standard. The D weighting
refers to an international standard that has already been withdrawn. Only some old
devices have the D-weighting. No frequency weighting, i.e. a so-called flat
characteristic curve is always referred to as Z weighting, flat or linear characteristic
curve.
⚫
Time weighting1
: Exponential function of time of a certain time constant, which
weights the square of a sound pressure signal. The weighting of the sound
pressure is higher if it corresponds more strongly to the current time and vice
versa. The time weightings "fast" and "slow" are used most often. "Impulse" should
not be used and was only provided for historical reasons.
⚫
SPL
: The sound level SPL calculated in the sound level meter is the largest time-
weighted sound level within one second.
-100,0
-90,0
-80,0
-70,0
-60,0
-50,0
-40,0
-30,0
-20,0
-10,0
0,0
10,0
1
10
100
1000
10000
31.5Hz~500Hz octave filter
31.5Hz
63Hz
125Hz
250Hz
500Hz
-100,0
-90,0
-80,0
-70,0
-60,0
-50,0
-40,0
-30,0
-20,0
-10,0
0,0
10,0
10
100
1000
10000
100000
1kHz~16kHz Octave Filter
1kHz
2kHz
4kHz
8kHz
16kHz