Pitch increases with increasing frequency. A high pitch sound corresponds to a high frequency sound wave while a low pitch sound corresponds to a low frequency sound wave.

The sound will travel faster in steel because speed of sound is fastest in solids.

The hearing aid amplifies the sound sent from the surroundings.

X sound is ultrasonic sound, Y sound is infrasonic sound and Z sound is audible sound.

When we touch a sound producing bell, we feel the vibration in it.

As we know that the audible frequency range for human being is 20 Hz to 20 kHz. So, it is an obvious thing that the frequency of bat is beyond this range due to which, we are usually unable to hear the screams of a bat.

The vibration due to the movement of closer player is more than others and the blind folded person easily imagine to which direction a player is nearer to her.

Since, the ultrasonic waves produce by the bats are high pitched which are not heard by the human beings. So, these ultrasonic waves after striking the insect send back an echo which is heard by the bat and finally it gets over on the insect and catches it

Since the voice box or the larynx in humans is the most important source of sound. So, two ligaments are known as vocal cords which are stretched across the larynx so that it leaves a narrow slit between them for the passage of air. Even when the lungs force air through the slit, the vocal cords vibrate producinq voice.

A stretched string on being set into vibrations forces the surrounding air to vibrate and this vibrating air in them affects our eardrum and produces an audible sound.

(a) String of sitar is a vibrating part of sitar.
(b) Since if we beat the dholak, then the membrane of dholak starts vibrating with high amplitude and as a fact, the loudness is directly proportional to the square of amplitude. Therefore, in the form of the loudness created by beating dholak
(c) The sound wave produced by flute is regular curving. So, there is no part of noise.Thus, we hear shrilling sound of flute.
(d) The values displayed by Anjali's grandfather are scientific methods and critical thinking.

As, we all hear sound through our ears. The moment like eardrum when sound enters in outer part of ear then it travels down a canal at the end of which a thin membrane is stretched tightly which is called the eardrum. It performs an important function. The stretched rubber sheets like eardrum sound vibrations which make the them vibrate (see figure). In this way the eardrum sends vibrations to the inner ear and the signal goes to the brain.