What can we hear?
Audible, infrasonic and ultrasonic sound.
Not everything is heard
A dog responds to a whistle that you cannot hear at all.
What do you think is true about sounds that people cannot hear?
What this lesson covers
The idea
Humans hear only 20 Hz to 20 kHz, the audible range, which varies between people and narrows with age; sound below 20 Hz is infrasonic and above 20 kHz ultrasonic.
Not everything is heard
A dog responds to a whistle that you cannot hear at all.
What do you think is true about sounds that people cannot hear?
- Some of them have frequencies outside the range people can hear
- They do not exist
- They have no frequency at all
Place the sounds
Choose a frequency to see where it lies. The four frequencies are only examples.
Our hearing range
The audible range, or human hearing range, is 20 Hz to 20 kHz (20000 Hz). It varies from person to person and decreases with age. Dogs, cats, bats and dolphins can detect ultrasound, and elephants can detect infrasound.
Humans hear sound only from 20 Hz to 20 kHz, the audible range. It varies from person to person and decreases with age. Sound below 20 Hz is infrasonic and sound above 20 kHz is ultrasonic.
Notes
Humans hear 20 Hz to 20 kHz (the audible range), which narrows with age. Below 20 Hz is infrasonic; above 20 kHz is ultrasonic.
Check yourself
What is the audible range of human hearing?
What are sound waves with a frequency below 20 Hz called?
A sound has a frequency of 30 kHz. What is it called?
What happens to the range of frequencies a person can hear as the person grows older?
- 2 Hz to 2 kHz. The audible range is 20 Hz to 20 kHz, which is 20000 Hz.
- 20 Hz to 20 kHz — correct. Yes!
- 200 Hz to 200 kHz. The human hearing range ends at 20 kHz.
- Ultrasonic waves. Ultrasonic waves have a frequency above 20 kHz.
- Audible waves. Audible waves are in the range of 20 Hz to 20 kHz.
- Infrasonic waves — correct. Yes!
- Ultrasonic — correct. Yes!
- Infrasonic. Infrasonic waves have a frequency below 20 Hz.
- Audible. The audible range ends at 20 kHz, so 30 kHz is above it.
- It increases. The audible range varies from person to person and decreases with age.
- It decreases — correct. Yes!
- It stays the same for everyone. The audible range varies from person to person and decreases with age.