Question

5. The threshold of human hearing at a frequency of 1.0 kHz is usually defined to be exactly 0 dB (for purposes of significant figures, consider this to be an exact, pure number). A research study shows that if exposed to 95 dB of a sound source for a long time, the threshold of hearing will shift upward to 32 dB. This accounts for why it is hard to hear normal conversations for some time after leaving a loud concert.

(a) What is the sound intensity, in W/m2, for a 32 dB sound level?

(b) For the original 95 dB sound exposure, if the sound source was isotropic (emitted equally in all directions), what would be the power (in W) of the sound source at its origin if you experienced 95 dB at a distance of 4.5 m away from the source?

Answer 1

We use the equation of sound intensity in terms of decibel sound level to get the sound intensity at 32dB.

To get the source power, we first find the sound intensity of the 95 dB source, then we find the intensity due to the source

at 4.5 m, we equate them to find the power of the source.