Sound

Tanusri Gururaj, Academic content writer of Physics at Edumarz

• Audible range of sound for humans:

20 Hz to 20000 Hz

• Infrasonic sound/infrasound:

Sound having frequency below 20 Hz. 

Rhinoceros use infrasound to communicate. The frequency is as low as 5 Hz. 

Some other animals which produce infrasonic sounds are whales and elephants. 

Earthquakes also produce low-frequency waves before the main shock waves hence alerting the animals who can hear infrasounds. 

• Ultrasonic sound/ultrasound:

Sound having frequency higher than 20 kHz. (1 kHz = 1000 Hz)

Some animals like dolphins, moths, porpoises, rats, and bats produce ultrasonic sounds. Dogs and children under the age of five can hear frequencies up to 25 kHz. 

Moths can hear the high-frequency squeaks of bats and can know when they are near. This helps moths to escape from them. 

• Hearing aid:

Used by people who suffer from hearing loss. They are electronic, battery-operated devices. 

How does a hearing aid work?

1. Receives sound through a microphone. 

2. Sound waves are converted to electrical signals using the microphone.

3. Electrical signals are amplified using an amplifier. 

4. Amplified signals are sent to the speaker of the hearing aid.

5. Amplified signals are converted to sound using the speaker. 

6. This is sent to the ear and helps to listen to sounds clearly.