The Sounds We Hear

Our living environment seems to be getting louder. Daily many are battered by sounds of varying intensities ranging from the noise of cars, buses and trucks in the streets to the racket of power tools in the work place. 

Sometimes we add to the problem by turning up the volume. One popular way of listening to music is through headphones attached to a portable CD or cassette player. According to Marshall Chasin, co-founder of the Musicians' Clinic of Canada, surveys conducted in Canada and in the United States indicate that youths are increasingly suffering loss of hearing caused by the use of headphones with the volume turned up.

But what is too loud?  Sound is characterized in three ways-by duration, by frequency, and by amplitude. Duration simply refers to the length  of time a sound is heard. A sound's frequency, or pitch, is described in cycles per second, or hertz. The range of audible frequency is from 20 to 20,000 cycles per second.

A sound's amplitude, or strength is measured in units called decibels (dB).  Normal conversation has sound level of approximately 60 decibels. Audiologists say that the longer you are exposed to anything louder than 85 decibels, the greater will be the eventual loss of hearing. The louder the sound, the faster the damage to hearing. A  Newsweek magazine report noted:  "Your ear can safely handle two  hours with a power drill (100 dB), but not more than 30 minutes in a noise video arcade (110 dB). Every 10-decibel increase on the sound scale represents 10 times  more ear-battering noise." Tests confirm that sound becomes painful at approximately 120 decibels. Incredibly, some home stereo equipment can produce sound at more than 140 decibels!   

To help you understand why loud sounds can damage  your hearing, let us consider what happens when sound waves reach your ears. 

Next time: How Our Hearing Functions

From the Awake!  magazine, 2002