If we have a machine contributing 90 dB and another contributing 93 dB, the combine noise level will be: (Si una mquina contribuye con 90 dB y otra con 93 dB, el nivel de ruido combinado ser:) Scale for Combining Decibels Difference between two decibel Amount to be added to larger level levels to be added (dB) to obtain decibel sum (dB) 0 3.0 1 2.6 2 2.1 3 1.8 4 1.4 5 1.2 6 1.0 7 0.8 8 9 0.5 10 0.4 11 0.3 12 Source: NIOSH (Industrial Noise Control Manual (NIOSH 79-117), 1978). + 0.6 0.2 0 3.0 1 2.6 2 2.1 3 1.8 4 1.4 5 1.2 6 1.0 7 0.8 8 0.6 9 10 0.4 11 0.3 12 0.2 Source: NIOSH (Industrial Noise Control Manual (NIOSH 79-117), 1978). ODOO 0.5 94.0 dB 91.5 dB 94.8 dB 95 dB