Sound frequencies higher than 20,000 Hz are called ultrasound. It is used as diagnostic tool in medical science. It is also used to relieve pains in joints, muscles. It is used to detect flaws in metal and structures, and to test the thickness of various parts.

Sound needs a medium for propagation. Take a metal or glass tumbler. Place a cellphone in it. Ask your friend to give a ring on this cellphone. Listen to the ring carefully. Now surround the rim of the tumbler with your hands. Suck all the air of the tumbler. Once again make a ring in cellphone. Sound will completely stop because air has been removed completely from the vessel and forms vacuum. Hence sound needs a medium for propagation.

The frequency determines the shrillness or pitch of a sound. A drum vibrates with low frequency. Therefore, it produces low pitched sound. Whistle has a high frequency and therefore, produces a sound of higher pitch.

The vocal cords in men are about 20 mm long. In women these are about 5 mm shorter. Children have very short vocal cords. This is the reason why the voices of men, women and children are different.

We can differentiate sounds on the basis of their amplitude and frequencies.

Yes, as the sound of children is shriller than the sound of adults. So, the frequency of sound produced by a child is more than that of an adult.

The sound travels through the different mediums i.e., solid, liquid or gases.

The sounds are different due to the shrillness or pitch of sound which can be determined by the frequency. If the frequency of sound is higher, we say that the sound has a higher pitch

Yes, the vocal cords vibrate to produce sound.

There is no atmosphere on the moon and sound waves need a medium to travel, so we cannot hear the sound on the moon.

Pitch is that characteristic of sound due to which distinction can be done between two sounds.

The lowest limit of audible frequency is 20 Hz.

The speed of sound decreases when it goes from solid to gaseous state.

T = 0.025 s,
\(v=\frac { 1 }{ T } =\frac { 1 }{ 0.025 } =40Hz\)

Amplitude of sound wave.

Sound wave cannot propagate in vacuum.

Ultrasound refers to sound that has a frequency above the audible range (20,000 Hz) of the human ear.

Pitch is perceptual to sensation. Frequency is a physical quantity that can be measured.

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 faster the bee vibrates its wings, the greater the frequency of the sound.

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

Voice chord.

The hearing aid amplifies the sound sent from the surroundings.

Temporary deafness is an ill effect of noise pollution.

As the amplitude of vibrations of floor is reduced and the sound of our steps becomes feeble, so due to this reason, we do not produce the loud sound when we walk on the carpet floor.

Amplitude is a name given to the maximum displacement of a vibrating body from its central position.

The sound which gives a pleasant sensation to our mind is known as the musical sound

Due to the small amplitude of their sound, babies have feeble sound.

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

Guitar and sitar are the two musical instrumenls which produce the sound by vibrating string.

Through water as a liquid medium, both whales and dolphins hear the sound.

The factor on which the quality of sound depends is the looseness or the tightness of the vocal cord.

It is the eardrum which vibrates and sends vibrations to the inner air, when we hear any sound.

We know that
Distance = Speed x Time
Distance = 330 x 5
= 1650 m
=1.65km (1 km=1000m)
So, she is standing at 1.65 km from the place where lightning occurs

The two ligaments which stretch across the larynx in such a way that it leaves a narrow slit between them for the passage of air, are known as vocal cords.

In most of the cases, we cannot see the vibrations because of its small amplitude.

Yes, while speaking the part which vibrates is called vocal cords. It is below the throat and creates vibrations while speaking.

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