[AK4679]
(3-2) Noise Suppression → Normal Operation
During noise suppressing operation, if the input moving average level set by NSOAF1-0 bits (Table 46) exceeds Noise
Suppression Threshold High Level set by NSTHH4-0 bits (Table 47), 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 48).
Moving Average Parameter
NSOAF1-0 bits
fs=8kHz
0.5ms
1.0ms
2.0ms
4.0ms
fs=16kHz fs=44.1kHz
00
01
10
11
4/fs
8/fs
16/fs
32/fs
0.3ms
0.5ms
1.0ms
2.0ms
0.1ms
0.2ms
0.4ms
0.7ms
(default)
Table 46. Moving Average Parameter Setting at Noise Suppression On
Noise Suppression
Threshold High Level [dBFS]
NSTHH4-0 bits
Step
00H
01H
02H
:
10H
:
(default)
−36.0
−37.5
−39.0
:
−60.0
:
1.5dB
1EH
1FH
−81.0
−82.5
Table 47. Noise Suppression Threshold High Level
NSGAIN2 NSGAIN1 NSGAIN0
Recovery Speed
16kHz
bit
bit
bit
8kHz
44.1kHz
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
0.3dB/ms
0.5dB/ms
1.1dB/ms
2.2dB/ms
4.5dB/ms
0.5dB/ms
1.1dB/ms
2.2dB/ms
4.4dB/ms
9.0dB/ms
1.5dB/ms
3.0dB/ms
6.0dB/ms
12.2dB/ms
24.7dB/ms
(default)
N/A
Table 48. Recovery Speed Setting from Noise Suppression to Normal Operation (N/A: Not available)
MS1402-E-06
2013/02
- 87 -
AKM [ ASAHI KASEI MICROSYSTEMS ]
