Refraction of Sound

A sound is a vibration that travels as a mechanical wave across a medium. It can spread via a solid, a liquid, or a gas as the medium. In solids, sound travels the quickest, comparatively more slowly in liquids, and the slowest in gases.

A sound wave is a pattern of disturbance caused by energy travelling away from the sound source. The constituents of sound are longitudinal waves. This demonstrates that vibrational particle propagation and the direction of energy wave propagation are parallel. When made to vibrate, atoms begin to oscillate. This continuous back-and-forth motion results in the formation of a high-pressure and a low-pressure zone in the medium. 

These high- and low-pressure zones are called compressions and rarefactions, respectively. As a result of these locations transmitting to the surrounding media, the sound waves go from one to the other.

Refraction of Sound

The bending of the sound waves when they enter a medium where the speed is different. Refraction, or bending of the wave path, is followed by a change in wave speed and wavelength. As a result, changing the medium (or its qualities) changes the speed of the wave. Refraction occurs when waves travel from one medium to another. Sound wave refraction is most noticeable when the sound wave passes through a material with progressively altering characteristics.

Condition of Refraction of Sound

The temperature of the medium has an impact on the speed of sound in the air, with the wave travelling more quickly at warmer temperatures and more slowly at cooler ones. The direction of propagation of sound waves varies when portions of the wave are in layers of a medium that are at different temperatures and, as a result, are moving at different speeds. This results in the refraction of sound waves.

ECHO

An echo is a repeating sound caused by sound waves being reflected back. Sound waves may bounce off smooth, hard objects in the same manner as a rubber ball does. Despite the fact that the sound’s direction changes, the echo sounds exactly like the original. Echoes can be heard in confined places with hard walls, such as wells, or in areas with a lot of hard surfaces. Echoes may be herded together in a canyon, cave, or mountain range. However, not all noises are reflected. If they come into contact with a soft surface, such as a cushion, they will be absorbed and will not bounce back.

Minimum Distance Required To Hear An Echo

An echo is only heard if the distance between the person making the sound and the stiff obstruction is sufficient for the reflected sound to reach the person at least 0.1 seconds after the original sound is heard. Otherwise, the echo is undetectable even when it reaches the ears. This value may be computed and is 17.2 m for air and 70 m for water.

Read, More

• Production and Propagation of Sound
• Characteristics of Sound Waves
• Audible and Inaudible Sounds

FAQs on Refraction of Sound

Question 1: What is meant by Refraction of Sound?

Answer:

The bending of the sound waves when they enter a medium where the speed is different is known as the refraction of sound.

Question 2: What is an Echo?

Answer:

An echo is a sound caused by the reflection of sound waves from a surface back to the listener. It is the reflection of sound, arriving at the listener sometime after the direct sound.

Question 3: What are the laws of refraction of light?

Answer:

There are two laws of refraction,

• The incident ray, the refracted ray, and the normal to the interface at the point of the incident all lie in the same plane.
• The ratio of the sine of the angle of incident and the sine of the angle of refraction is constant for given pair of media

Question 4: State two conditions for an echo to take place.

Answer:

The necessary conditions for the formation of an echo,

1. The minimum distance between the source of sound and the reflecting body should be 17 meters.
2. The wavelength of sound should be less than the height of the reflecting body.

Question 5: What do you mean by the reflection of sound?

Answer:

The reflection of sound is actually similar to the reflection of light. Sound abides by different laws of reflection, in which the angle of incidence does prove equal to the angle of reflection. In addition, sound rebounds from the surface of either solid or liquid similar to a billiard ball. For successfully experiencing the reflection of sound, it is important that the surface should be polished or rough, and that too of a considerably large size.

Question 6: What is the condition for the reflection of a sound wave?

Answer:

The two laws concerned with sound reflection are as follows:

• The incidence angle will always be equal to the reflection angle.
• The incident sound waves, the normal at incidence point and reflected wave, all rest in a common plane.

Question 7: Name a device in which the reflection of a sound wave is used.

Answer:

Stethoscope: A stethoscope is a medical diagnostic instrument based on multiple reflections of sound waves. This is used by doctors for listening to the sounds produced inside the body, particularly in the heart or lungs.