Residents of Hawaii are warned of the approach of a tsunami by sirens build up on the tops of towers. Assume that a siren generates a sound which consists of an intensity level of 120 dB at a distance of 2 m. Treating the siren as a point source of sound, and avoiding reflections and absorption:
i) Determine the sound intensity level heard by the observer at a distance of 12 m.
ii) Determine the sound intensity level heard by the observer at a distance of 21 m?
iii) Explain how far away can the siren be heard? (I = threshold of hearing)