The loudness and pitch of a sound depend on

The intensity level of a sound of intensity $I$ is $30 \, dB$. The ratio $\frac{I}{I_0}$ is (where $I_0$ is the threshold of hearing).

How many times more intense is a $60 \ dB$ sound than a $30 \ dB$ sound?

The power of a sound from the speaker of a radio is $20 \text{ mW}$. By turning the knob of the volume control,the power of the sound is increased to $400 \text{ mW}$. The power increase in decibels as compared to the original power is .... $\text{dB}$

Two identical sounds $S_1$ and $S_2$ reach at a point $P$ in phase. The resultant loudness at point $P$ is $n \, dB$ higher than the loudness of $S_1$. The value of $n$ is

Four sources of sound each of sound level $10\,dB$ are sounded together,the resultant intensity level will be ... $dB$