Out of the following musical instruments, which is '$NOT$' a percussion instrument?

$A$ hearing test is conducted on an aged person. It is found that her threshold of hearing is $20 \, dB$ at $1 \, kHz$ and it rises linearly with frequency to $60 \, dB$ at $9 \, kHz$. The minimum intensity of sound that the person can hear at $5 \, kHz$ is

To raise the pitch of a stringed musical instrument,the player can:

In an orchestra,the musical sounds of different instruments are distinguished from one another by which of the following characteristics?

When we hear a sound,we can identify its source from

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 .... $\text{dB}$