Sound

Sound Reflection

Sound travels in all medium and spreads in all directions. In case of a massive explosion, we hear the sound equally in all directions surrounding the explosion. We can direct the sound and we can receive the sound in a particular direction. Megaphone is a device where the sound is directed. Megaphone is a large funnel-shaped device which is used to channelize the sound in a particular direction. Sound can reflect due to hard surface. Due to this reason in big auditorium backstages have a curved surface so that sound can be better projected and heard.  Sound reflection is similar to the reflection of light.

The laws of reflection of light are also similar to the laws of reflection of sound. Here the hard surface acts as a reflection mirror. Like light sound is also reflected from the surface. Sound falls in the surface and reflects back from the surface to the ear. The sound which reflects back from the sound is known as an echo. Big walls of the building, mountains, tunnels can produce echo from the original sound.

Reflections of Sound

Sound is similar to light and it propagates like a mechanical wave through the medium of air and water. In case of sound also the angle of reflection of sound is equal to the angle of incident of sound. Also the reflected sound, incident sound and normal sound all belong to the same plane.

Two laws of sound are- i) The angle of incident is equal to the angle of reflection. ii) Incident sound, reflected sound and normal sound all belong in the same plane.

Application of Reflection of Sound

Echo:

Echo is basically repeated sound as sound waves are reflected back from the hard and uneven surface. Sound can bounce off from the surface as rubbers ball bounces off the ground. Echo sounds same as original sound although sound changes its direction. If sound falls in a soft surface such as it can’t reflect. It is absorbed by the surface. This is the reason echo can be heard when the sound reflects from a hard surface, walls, mountain, tunnels. Bats and dolphins use echo to detect obstacles. They also use echo to navigate in the ocean.

In sound navigation and ranging, technique or SONAR experts use echo. Submarine, ship all use SONAR to detect underwater objects such as submerged submarine, sunken ships, iceberg etc. In SONAR the ship or submarine send ultrasonic sound waves and then the received signal is analysed to detect the unseen objects.

Hearing Aid:

Hearing Aid is a device which is used to improve the hearing of a person who has a disability of hearing. It is a battery-powered electronic device which is designed small enough to wear in or behind the ear. The working principle of the hearing aid is a small microphone is there which picks up the sound and the amplifier makes the sound louder. Now the receiver sends the amplified sound to the ear of the patient. But this hearing add treatment is not very much beneficial. Very few people can hear improved voice by hearing aid.

Sound Board:

The shape of the soundboard is concave and the board is placed behind the speaker in large auditorium and halls so that the sound can easily be heard to the person who is sitting in a considerable distance. The sound falls in the concave soundboard from a different direction and reflected back from the concave surface in the same direction so that the sound can’t spread in various directions. Due to this reason sound is distributed uniformly all over the auditorium or halls.

FAQs about Sound Reflection

Q.1 Describe reverberation and how can we minimize reverberation?

Answer:  In large hall due to the repeated reflection persistence of sound can happen. This is reverberation. We can minimize reverberation by covering the ceiling and walls which has sound-absorbing materials.

Q.2: Write three characteristics of sound waves.

Answer: Sound waves propagate as a mechanical wave. Sound waves are also longitudinal waves. Sound waves are the result of vibrations.

Q.3: Describe SONAR:

Answer: SONAR is a hearing technique which is in use in ships, submarine to detect unseen objects in the sea. The ships or submarines send the ultrasonic waves in water and then analysed the received signal to detect unseen objects such as broken or sunken ships, iceberg, sea hills.

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