Two sources of noise, adjacent to each other in a room, have sound pressure levels of 30 and 40 decibel (dB). The combined sound pressure level in the room is _________ dB(rounded off to 2 decimal places). Use reference sound pressure as $20 \mu Pa$.

Question

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Step 1: Convert each dB level to its power ratio. $$ P_1 = 10^{\frac{30}{10}} = 1000, \quad P_2 = 10^{\frac{40}{10}} = 10000 $$ Step 2: Sum the power ratios. $$ P_{\text{total}} = 1000 + 10000 = 11000 $$ Step 3: Convert the total power ratio back to dB. $$ L_{p_{\text{total}}} = 10 \log_{10}(11000) \approx 40.00 \, \text{dB} $$

Two sources of noise, adjacent to each other in a room, have sound pressure levels of 30 and 40 decibel (dB). The combined sound pressure level in the room is _________ dB(rounded off to 2 decimal places).
Use reference sound pressure as $20 \mu Pa$.

Correct Answer: 40

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