C
A
70 dB
A
B
70 dB
C
A
7 dB
C
A
A
B
7 dB
A
B
B
A
B
A
7 dB
B
A
A
A
7 dB
B
A
7 dB
A
A
D
A
7 dB
A
B
7 dB
A
B
A
71 dB