The frequency range of human hearing.

The frequency range of human hearing is typically between approximately 20 Hz to 20,000 Hz (20 kHz). The ability to hear sounds within this range can vary among individuals and can be influenced by factors such as age and exposure to loud noises.

Sounds with frequencies below 20 Hz are generally perceived as vibrations or “felt” rather than heard. These extremely low-frequency sounds are known as infrasound. Higher sounds at the other end of the frequency above 20,000 Hz (20 kHz) are classified as ultrasonic and are typically beyond the range of human perception.

As we age our ability to hear higher frequencies tends to diminish, a condition which is known as presbycusis. 

What happens when we are exposed to very loud noise?

When we are exposed to very loud noise, a number of things can happen.

Delicate hair cells in the inner ear, which are responsible for converting sound vibrations into electrical signals for the brain, can be damaged.  Once the hair cells are damaged or even worse destroyed, they cannot  regenerate, resulting in permanent hearing loss.

Tinnitus, which is the perception of ringing, buzzing, or other phantom sounds in the ears can be triggered or the condition can worsen when exposed to loud noise.  Tinnitus can be temporary or permanent and can significantly impact a person’s quality of life.

Exposure to loud noise can also impact temporarily in our ability to hear softer sounds.  Our ears become  less sensitive to certain frequencies and sound is muffled.  In most cases this is temporary and after a period of time hearing returns to normal.  This is referred to as TTS (Temporary Threshold Shift).

Some people may develop hyperacusis, which is an increased sensitivity to sound. Even moderately loud sounds can be perceived as uncomfortable or painful, leading to a heightened distressing response.

Prolonged or repeated exposure to loud noise can result in permanent hearing loss (see table below for examples of  A-weighted sound pressure levels and exposure times.  This type of hearing loss, known as noise-induced hearing loss (NIHL), typically affects the high-frequency range first. Over time, it can progress to impact other frequencies and lead to a permanent reduction in hearing ability.

How can we protect our hearing?

Be aware of exposure times to loud noises.

Wear hearing protection like head phones or ear plugs in noisy environments.

Limit exposure by taking regular breaks in noisy environments.

Do not play headphone or earphones at high volume levels.