The noise of a cheering crowd at a game can be deafening! Really.
The Ear and Hearing
The ear is a complex organ that senses sound energy so we can hear. Hearing is the ability to sense sound energy and perceive sound. All of the structures of the ear that are involved in hearing must work well for a person to have normal hearing. Damage to any of the structures, through illness or injury, may cause hearing loss. Total hearing loss is called deafness. To learn more about hearing loss, watch the animation at this URL: http://www.youtube.com/watch?v=YpIptQSEEjY.
The most common cause of hearing loss is exposure to loud sounds. Loud sounds can damage hair cells inside the ears. Hair cells change sound waves to electrical signals that the brain can interpret as sounds. Louder sounds, which have greater intensity than softer sounds, can damage hair cells more quickly than softer sounds. You can see the relationship between sound intensity, exposure time, and hearing loss in the following Figure below. The intensity of sounds is measured in decibels (dB).
Q: What is the maximum amount of time you should be exposed to a sound as intense as 100 dB? What might make a sound this intense?
A: You should be exposed to a 100-dB sound for no longer than 15 minutes. An example of a sound this intense is the sound of a car horn.
Hearing loss caused by loud sounds is permanent. However, this type of hearing loss can be prevented by protecting the ears from loud sounds. People who work in jobs that expose them to loud sounds must wear hearing protectors. Examples include construction workers who work around loud machinery for many hours each day. But anyone exposed to loud sounds for longer than the permissible exposure time should wear hearing protectors. Many home and yard chores and even recreational activities are loud enough to cause hearing loss if people are exposed to them for too much time. You can see examples in the Figure below.
These activities expose people to dangerously loud sounds that can cause hearing loss.
How Hearing Protectors Work
You can see two different types of hearing protectors in the Figure below. Earplugs are simple hearing protectors that just muffle sounds by partially blocking all sound waves from entering the ears. This type of hearing protector is suitable for lower noise levels, such as the noise of a lawnmower or snowmobile.
Electronic ear protectors work differently. They identify high-amplitude sound waves and send sound waves through them in the opposite direction. This causes destructive interference with the waves, which reduces their amplitude to zero or nearly zero. This changes even the loudest sounds to just a soft hiss. Sounds that people need to hear, such as the voices of co-workers, are not interfered with in this way and may be amplified instead so they can be heard more clearly. This type of hearing protector is recommended for higher noise levels and situations where it’s important to be able to hear lower-decibel sounds.
- Hearing is the ability to sense sound energy and perceive sound. The ear is the organ that senses sound and allows us to hear. Damage to structures of the ear may cause hearing loss. Total hearing loss is called deafness.
- The most common cause of hearing loss is exposure to loud sounds. Loud sounds damage hair cells in the ear that are needed for hearing. Louder sounds damage hair cells more quickly than softer sounds.
- Hearing loss caused by loud sounds can be prevented by protecting the ears from loud sounds with hearing protectors. They keep sound waves out of the ears or reduce the amplitude of sound waves.
Watch the video about two types of hearing loss at the following URL. Then compare and contrast the two types. http://www.careflash.com/video/hearing-loss
- What is hearing?
- How is deafness defined?
- How can loud sounds, like a cheering crowd at a game, contribute to hearing loss?
- Write a public service announcement explaining how and why to protect the ears from loud sounds.