A sound is a vibration that propagates through a medium in the form of a mechanical wave. The medium in which it propagates can either be a solid, a liquid or a gas. Sound travels fastest in solids, relatively slower in liquids and slowest in gases.
Reflection of Sound waves
Sound bounces off the surface of the medium which can be a solid or a liquid. In order to make the reflection of sound to occur, the surface can be of large size and can be either rough or polished.
Bouncing back of soundwaves from the surface of solid or liquid is known as a reflection of sound. Reflection of sound is responsible for many interesting phenomena such as Echoes and Reverberation. Like the reflection of light, the reflection of Sound follows laws too.
Reflection of sound is based on the two laws and they are:
- The incidence angle is always equal to the reflection angle.
- The incident sound wave, the normal, and the reflected wave, all rest in a common plane.
When a sound hits a hard surface, it reflects back to its source. This reflection of sound is otherwise is called an echo. Hard surfaces have a tendency to reflect sound while soft surfaces absorb sound and silence them. If the frequency of the sound wave is low, then the sound wave will not get reflected.
Following are the practical applications of reflection of sound waves are:
- Reflection of sound is used to measure the distance and speed of underwater objects. This method is known as SONAR.
- The working of a stethoscope is also based on the reflection of sound. In a stethoscope, the sound of the patient’s heartbeat reaches the doctor’s ear by multiple reflections of sound.
- The working of a hearing aid is based on the reflection of sound. In a hearing aid, the sound waves are reflected into a slimmer area so as to direct the sound to the ear.
- The soundboard is based on the reflection of sound. Here, the sound waves are uniformly reflected can be seen in the auditorium. This helps in improving quality.
Following is the diagram which explains how does the soundboard works: