SmartSMS User Manual
Soft dB inc.
User Manual
p. 70
7. Active Adjustment System
The SmartSMS active adjustment system allows the level of the masking sound to be automatically
adjusted depending on the acoustical activity in the room.
The technique used to control the output volumes is based on sound level sensors located in the
zones where the active control is applied. The system computes the volume modifications
according to the acoustical activity in the room. Note that the shape of the resulting spectra in the
room does not change. The target masking spectrum is only shifted up and down (Figure 63).
Variation of the masking spectrum
10
15
20
25
30
35
40
45
50
55
80
125
200
315
500
800
1250 2000 3250 5000 8000
Frequncy (Hz )
S
P
L
dB
Target spectrum (45 dBA)
Lower masking spectrum (ex. 40 dBA)
Higher masking spectrum (ex. 48 dBA)
Figure 63: Example of the resulting variation of the masking spectrum in a room
This adjustment is possible due to an advanced signal processing technique that can precisely
make the distinction between the activity in the room and the sound masking. This distinction is
essential to achieve a stable and accurate control of the output volumes.
The active control can be achieved independently in different zones of the masking sound system.
Variation of the target
masking spectrum
