Types of sound

• Sound can be of different types- soft, loud, pleasant unpleasant, musical, audible (can be heard), inaudible (cannot be heard), etc.

Audible and Inaudible Sounds:

• Human ear are sensitive only to a certain range of frequencies, 20 Hz to 20,000 Hz. Human cannot hear sound waves of frequency below 20 Hz and above 20,000Hz.
• For human ear, the range of audible frequencies is roughly from 20 to 20,000 Hz.
• Dogs have the ability to hear very high-pitched sounds.
• Sound waves of frequencies below 20Hz are called infrasonic waves, and those of frequencies above 20,000Hz are called ultrasonic waves.

Application of ultrasonic sound waves:

• Ultrasonic sound waves can be applied in technologies such as Sonar. Sonar stands for Sound Navigation Ranging. It is used in navigation of ships, to map sea beds, and in submarines.
• Ultrasound is used for scanning and imaging the body for stones, tumors and foetus.
• It is used for relieving pain in muscles and joints.
• In industries it is used for detecting finer faults in metal sheets.
• It is also used for homogenizing milk in milk plants.