News

Say What?

Monday July 10, 2006
Dr. Richard Galich

The range of human hearing is broad. It is so, at least, at the beginning of life.

The sounds that we hear are actually vibrations of air moving away in waves from the source of the sound, much like the ripples produced by throwing a stone into a pool of water. The number of vibrations per second will determine the pitch of a sound. Pitch, or the frequency of sound waves, is measured in vibrations per second. The human ear can hear over a very wide range of frequencies, from as low as 20 waves (cycles) per second to over 20,000 cycles per second.

In general, the ability to hear the very high-pitched sounds, or frequencies, is best in early childhood, with gradual decline throughout life. A normal adult may have difficulty hearing frequencies over 10,000 cycles per second. The gradual decline in high-pitched hearing can be accelerated by loud noise exposure, such as firecrackers, jackhammers, and even very loud music. Fortunately, hearing of human speech, and thus communicating, involves the lower frequency range of hearing; the frequency range of 300 to 4000 cycles per second is most essential for communication.

An interesting sideline to this phenomenon of high pitch hearing decline with age is a recent story of England. Adolescents and other young “hooligans” would hang out in front of businesses and create a disturbance with their bantering; this annoyed the shopkeepers and their customers. Enter Compound Security, a company which introduced “the Mosquito”, a very loud, high-pitched, earsplitting 17,000 cycles per second tone. The noise-producing device was mounted at business entrances. The sound was only heard by young ears; adults, who no longer hear that frequency, were unaffected. The annoyance factor of the loud, high-pitched sound was meant to disperse the loitering youngsters.

Ingenious? Read on.  A New York high school freshman, David H., downloaded a version of the high-pitched sound from a British website and transferred it to his cell phone…as his ring tone. He shared the ring tone with his friends. In David’s school, cell phones have to be turned off during class. The high-pitched ring tone allowed text messaging unabated during class. The teacher, and most people over 30 years of age, cannot hear it. David’s new device altered the balance of power between students and their keepers. When confronted about his deed, David responded, “I guess the school will have to hire younger teachers”. 

Dr Richard Galich is a medical doctor specializing in disorders of the ears, nose and throat, head and neck surgery, and facial plastic surgery. He accepts appointments at Drummond Medical Group, 760-446-4571.