Question

6. Sound level measurements were made near an industrial machining operation. The ambient level measured with the most significant source turned off was 78.3 dB. When the noise source was turned on, the sound pressure level, measured at the same location, was 82.4 dB. Calculate the sound pressure level of the noise source as if it were the only active noise source. That is determine its contribution to the total noise level

Answer 1

Let I_a = sound Intensity of ambient I_n = sound intensity of noise surface implies 78.3 = 10 log_10 (I_a/I_0) implies log (I_a/I_0) = 7.83 implies I_a = I_0 times 10^7.83 (21) and 82.4 = 10 log_10 (I_a + I_n/I_0) implies log_10 (I_a + I_n/I_0 = 8.24 implies I_a + I_n = I_0 1068.24 implies I_n = I_a times 10^8.24 - I_a = I_0 times 10^8.24 - I_0 times 10^7.83 = I_0 (10^8.24 - 10^7.83) beta = 10 log_10 (I_n/I_a) = 10 logg_10 [I_0 (10^8.24 - 10^7.83)/I_0] = 10 log_10 (10^8.24 - 10^7.83) = 80.26 dB implies beta = 80.26 d B