AK4695 Datasheet, PDF (50/107 Pages) Asahi Kasei Microsystems – 24bit 4ch CODEC with MIC/HP/SPK/LINE-AMP

[AK4695]
(3-2) Noise Suppression → Normal Operation
During noise suppressing operation, if the input moving average level set by NSOAF1-0 bits (Table 44) exceeds Noise
Suppression Threshold High Level set by NSTHH4-0 bits (Table 45), the operation switches to normal operation from
noise suppressing operation.
This recovery operation sets the volume automatically to 0dB with the soft transition of the recovery speed set by
NSGAIN2-0 bits (Table 46).
NSOAF1-0 bits
Moving Average Parameter
fs=8kHz fs=16kHz fs=48kHz
00
4/fs
0.5ms
0.3ms
0.1ms
01
8/fs
1.0ms
0.5ms
0.2ms
10
16/fs
2.0ms
1.0ms
0.3ms (default)
11
32/fs
4.0ms
2.0ms
0.7ms
Table 44. Moving Average Parameter Setting at Noise Suppression On
NSTHH4-0 bits
Noise Suppression
Threshold High Level [dB]
Step
00H
36.0
01H
37.5
02H
39.0
:
10H
:
60.0
1.5dB
:
:
1EH
81.0
1FH
82.5
Table 45.Noise Suppression Threshold High Level
(default)
NSGAIN2 NSGAIN1 NSGAIN0
bit
bit
bit
Recovery Speed
8kHz
16kHz
48kHz
0
0
0
0.3dB/ms 0.5dB/ms 1.6dB/ms
0
0
1
0.5dB/ms 1.1dB/ms 3.3dB/ms (default)
0
1
0
1.1dB/ms 2.2dB/ms 6.6dB/ms
0
1
1
2.2dB/ms 4.4dB/ms 13.2dB/ms
1
0
0
4.5dB/ms 9.0dB/ms 26.9dB/ms
1
0
1
1
1
0
N/A
1
1
1
Table 46. Recovery Speed Setting from Noise Suppression to Normal Operation (N/A: Not available)
MS1463-E-01
- 50 -
2014/12