AK4951AEN Datasheet, PDF (43/105 Pages) Asahi Kasei Microsystems – 24bit Stereo CODEC with MIC/HP/SPK-AMP

[AK4951A]
■ Automatic Wind Noise Reduction Filter
The AK4951A has an automatic wind noise reduction filter that is controlled by AHPF bit. The automatic
wind noise reduction filter is ON when AHPF bit = “1”. It attenuates the wind noise when detecting a wind
noise and adjusts the attenuation level dynamically. When AHPF bit = “0”, the audio data passes this
block by 0dB gain. SENC2-0 bits control the wind noise detection sensitivity, and STG1-0 bits control the
attenuation level of the maximum attenuation. SENC2-0 bits and STG1-0 bits must be set when AHPF bit
= “0” or PMPF bit = “0”.
The automatic wind noise reduction filter has peak detection function for voice band. When the AK4951A
detects peak level in voice band during the wind noise reduction, it suppresses the wind noise reduction
level automatically in order to ensure the voice band bandwidth. When VODETN bit = “1”, the voice peak
detection is disable, and the wind noise reduction will continue working even if the voice peak level
increases. VODETN bit must be set when PMPFIL bit = “0”.
Table 29. Wind Noise Detection Sensitivity
SENC2-0 bits Sensitivity Level
000
0.5
Low
001
1.0
010
1.5
011
2.0
(default)
100
2.5
101
3.0
110
3.5
111
4.0
High
Table 30. Attenuation Level of Automatic Wind Noise Reduction Filter
STG1-0 bits Attenuation Level
00
Low
Low (default)
01
Middle1
10
Middle2
11
High
High
016001936-E-00
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2016/03