| Deutsche Version |
Weighting filter after DIN EN 61672-1 2003-10 (DIN-IEC 651)
Calculation: Frequency f → dBA und dBC
At sound level analyzers the display (attack time tin) is time weighted. There are different settings:
| Slow (S): | tin | = | 1000 ms | |||
| Fast (F): | tin | = | 125 ms | |||
| Pulse (I): | tin | = | 35 ms, | tout | = | 1500 ms |
| Note - Comparing dBSPL and dBA: There is no conversion formula for measured dBA values to sound pressure level dBSPL or vice versa. |

The A-weighting filter curve is defined from 20 Hz to 20 kHz.
dBA: The decibel A filter is widely used. dBA roughly corresponds to the inverse
of the 30 dBSPL or 40 dBSPL at 1 kHz equal-loudness curve for the human ear.
An A-curve always provides for "nice" values when low frequency noise signals are included.
An A-filter of a measured motorcycle noise must show untrue values. You should know that.
dBC: The decibel C filter is practically linear over several octaves and is
suitable for subjective measurements at higher sound pressure levels.

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Comparing dBA and dBC
| Relative Response (dB) | Frequency f in Hz | ||||||||
| 31.5 | 63 | 125 | 250 | 500 | 1000 | 2000 | 4000 | 8000 | |
| dB(A) | −39.5 | −26.2 | −16.2 | −8.7 | −3.2 | 0 | 1.2 | 1 | −1.1 |
| dB(C) | −3 | −0.8 | −0.2 | 0 | 0 | 0 | −0.2 | −0.8 | −3 |
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