Range of Hearing in Humans

The range of sound – on the basis of the range of frequency of a sound, it is categorized into ultrasound and infrasound.

Human auditory range is between 20 Hz and 20000 Hz.

Infrasound:

• Infrasound refers to the sound with frequency lower than 20Hz which cant be heard by humans.
• Is used to stabilize myopia in young kids.
• Infrasound is influenced by the atmosphere so it can be used to monitor the activities of the atmosphere.
• In particular, natural disasters such as volcanic eruptions, earthquakes etc can be forecasted by monitoring the infrasonic waves.

Ultrasound:

Ultrasound refers to the sound with frequency higher than the upper limit(20KHz) of frequency audible to normal human ears.

Ultrasound is commonly used to find flaws in materials to measure the thickness of objects, to find physical abnormalities in various parts of human body as well as in the form of a sound ranging device called sonar.

Ultrasound is not influenced by any such factors.

In particular, ultrasound is also used in micro welding. The weld is produced by the application of higher frequency vibratory energy as the parts are held together with force.

Hearing Aid:

The Hearing Aid contains a microphone which receives the sound from the outer atmosphere and converts it into electrical energy. This electrical energy is passed through an amplifier which amplifies the sound and then moves it to a speaker. The speaker then converts the electrical signal into sound waves and sends it to the ear and provides a clear hearing.