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. 2014 Sep 13;53(1):21–27. doi: 10.2486/indhealth.2013-0003

Table 2. Filter coefficients for the C-weighting filter.

a[0]	(16 ω₄′) + (16 ω₁′) + (4 ω₁′²) + (16 ω₄′ . ω₁′) + (4 ω₄′ . ω₁′²) + (ω₄′² . ω₁′²) + (4 ω₄′²⁾ + 16 + (4 ω₄′² . ω₁′)
a[1]	(8 ω₄′²) – 32 + (6 ω₄′² . ω₁′²) + (32 ω₄′ . ω₁′) + (16 ω₄′ . ω₁′²) + (8 ω₁′²) + (16 ω₄′² . ω₁′)
a[2]	–16 + (20 ω₄′ . ω₁′²) – (48 ω₄′) – (4 ω₄′²) – (4 ω₁′²) + (15 ω₄′² . ω₁′²) – (48 ω₁′) + (20 ω₄′² . ω₁′) – (16 ω₄′ . ω₁′)
a[3]	64 – (16 ω₁′²) – (64 ω₄′ . ω₁′) + (20 ω₄′² . ω₁′²) – (16 ω₄′²)
a[4]	–(4 ω₁′²) + (15 ω₄′² . ω₁′²) – (4 ω₄′²) + (48 ω₁′) – (16 ω₄′ . ω₁′) – (20 ω₄′ . ω₁′²) – 16 – (20 ω₄′² . ω₁′) + (48 ω₄′)
a[5]	(8 ω₄′²) – (16 ω₄′² . ω₁′) + (8 ω₁′²) + (32 ω₄′ . ω₁′) – (16 ω₄′ . ω₁′²) + (6 ω₄′ ². ω₁′ ²) – 32
a[6]	–(4 ω₄′ . ω₁′²) + (16 ω₄′ . ω₁′) + (ω₄′² . ω₁′²) – (4 ω₄′² . ω₁′) + 16 – (16 ω₁′) – (16 ω₄′) + (4 ω₄′²) + (4 ω₁′²)
b[0]	4 ω₄′²
b[1]	8 ω₄′²
b[2]	–4 ω₄′²
b[3]	–16 ω₄′²
b[4]	–4 ω₄′²
b[5]	8 ω₄′²
b[6]	4 ω₄′²
G_C	10^{(–0.062/20)}

The normalization constant, G_C, is used to provide 0 dB gain at 1 kHz.