The walls of the halls built for music concerts should

$A$ source of sound emits $200\pi \text{ W}$ power which is uniformly distributed over a sphere of $10 \text{ m}$ radius. What is the loudness of sound on the surface of the sphere?

Learned Indian classical vocalists do not like the accompaniment of a harmonium because

In a city,the sound intensity level increases uniformly by about $1 \ dB$ annually. How many years will it take for the intensity of sound to become double?

If the threshold of hearing is assumed to be the reference $(0 \ dB)$,then the threshold of pain is taken to be $120 \ dB$. Let the corresponding sound intensities be $I_0$ and $I$ respectively. Then $\frac{I_0}{I}$ is:

The tones that are separated by three octaves have a frequency ratio of