Understanding Sound Energy

Sound Energy

• Sound energy is a form of energy that allows us to hear sounds.
• Sound is produced when an object vibrates, such as a tuning fork, stretched rubber band, vocal cords, strings, or air column.

Propagation of Sound

• Sound requires a medium to propagate, which can be a gas, liquid, or solid.
• Sound waves propagate through compressions and rarefactions of particles in the medium.
• Sound is a mechanical wave that cannot travel through vacuum.
• Sound waves are longitudinal waves, where particles move in a direction parallel to the propagation of the disturbance.

Speed of Sound

• The speed of sound depends on the properties of the medium, including pressure, density, and temperature.
• Speed of sound: Solids > Liquids > Gases.
• Speed of sound in air: 331 m/s at 0°C and 344 m/s at 22°C.
• When a source emits sound with speed greater than the speed of sound in air, it creates a sonic boom.

Reflection of Sound Waves

• Sound waves follow the laws of reflection, bouncing off the surface of solid and liquid.
• The phenomenon where a sound produced is heard again due to reflection is called an echo.
• Minimum distance for obstruction or reflective surface to hear an echo: 17.2 m.
• Multiple echoes can be heard due to multiple reflections.

Reverberation

• The persistence of sound due to multiple reflections is called reverberation.
• Examples: Auditorium and a big hall.
• Excessive reverberation is undesirable, and can be reduced by using sound-absorbing materials.

Uses of Multiple Reflection

• Megaphone, horns, musical instruments (e.g. trumpets)
• Stethoscope
• Concert halls, conference halls, cinema halls

Range of Hearing

• Human ear can hear sound in a frequency range of about 20Hz to 20kHz.
• Sounds of frequencies less than 20Hz are known as infrasonic sound or infrasound.
• Sounds of frequency greater than 20kHz are known as ultrasonic or ultrasound.

Applications of Ultrasound

• Industry: Cleaning instruments and electronic components.
• Medical science: Echocardiography, Ultrasonography, Breaking small stones formed in the kidneys.
• Communication: SONAR (Sound Navigation And Ranging)

SONAR

• Technique that uses sound or ultrasonic waves to measure distance and detect objects on or under the water surface.
• SONAR consists of a transmitter and detector mounted on a boat or ship.
• Distance can be measured using the formula: 2d = v × t.

Explore the concept of sound energy and how it enables us to hear various sounds. Learn about the properties of sound and how objects vibrating can produce different types of sound.