Question

Sound intensities, I, are often compared with the threshold of human hearing, I_0, which is about 10^-12 watts per meter squared. The relative intensity, R, of a sound is given by the equation: R = 10log(I/I_0)





i. The intensity of a whisper is about 300 times as loud as the threshold of human hearing. Find the relative intensity, R, of a whisper in decibels.





ii. Suppose a burglar alarm has a rating of 120 decibels. Compare this intensity to the threshold of human hearing.

Answer 1

i. what is 10log300? Ans 10*2*log3 work that out, about 9db
ii. Threshold human hearing: 0 db so 120/10=12, so ...