MSM7731-02 OKI [OKI electronic componets], MSM7731-02 Datasheet - Page 44

• Manufacturer Part Number: MSM7731-02
• Description: Dual Echo Canceler & Noise Canceler with Dual Codec for Hands-Free
• Manufacturer: OKI [OKI electronic componets]

Noise Attenuation
There is a trade-off between noise attenuation and sound quality. In other words, increasing the noise attenuation
deteriorates sound quality, and decreasing the noise attenuation improves sound quality. The following
combinations of noise attenuation levels can be selected with this device. Select the noise attenuation appropriate
to the sound quality.
When selecting the following combinations by the method of internal data memory access, set the
NCSEL1/NCSEL2 pin and bit as follows:
Attenuation of ATT Function
The attenuation (ATT values) of echo canceler ATT functions (ATTsL/ATTrL, ATTsA/ATTrA) can be selected
from the following combinations. When selecting the attenuation, take note of the following.
When selecting the following combinations by the method of internal data memory access, set the AATT pin and
bit as follows:
1 Semiconductor
ATT attenuation [dB]
Noise attenuation [dB]
6 (default)
17 (default)
address
address
NCSEL1 pin and bit (CR1-B0) = 0
NCSEL2 pin and bit (CR12-B2) = 0
1. Increasing the attenuation causes almost half duplex.
2. Increasing the attenuation causes the sound of the beginning and ending of words to be cut.
3. Increasing the attenuation remarkably changes the sound volume of background noise.
AATT pin and bit (CR5-B1) = 0
12
18
24
13.5
14
12
11
10
(by turning On or OFF the ATTs/ATTr)
9
8
8
8
7
7
6
Data 1
0199h
4000h
2000h
1000h
0800h
Data 1
01C8h
2000h
3333h
3333h
4666h
4666h
5999h
6666h
5999h
2000h
3333h
4666h
5999h
6666h
Data 2
019Ch
4200h
4000h
4000h
4000h
Data 3
019Fh
4200h
2200h
2000h
2000h
Data 2
01C2h
0005h
0005h
0004h
0005h
0003h
0005h
0005h
0002h
0001h
0001h
0001h
0001h
0001h
Data 4
01A2h
4200h
2200h
1200h
1000h
Voice quality
Better
FEDL7731-02-04
Best
MSM7731-02
Data 5
01A5h
4000h
2000h
1000h
0800h
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