The sound we hear is measured in terms of the pressure of the sound waves on our ears and is expressed in decibels or dB. Sound ranges from about 40 dB, as in an office or library, 50 dB in a large office, 70 dB in freeway traffic, 85 dB in a noisy restaurant, 90 dB in shouted conversation, 110 dB in a symphony concert or near a baby crying, 150 dB near a jet engine at takeoff max power, or 180 dB by a rocket launching.

Noise concerns are not new. In a 1978 study of all noise sources, for the Federal Interagency Committee on Noise, Dr. T.J. Schultz ascertained that human beings exposed to all sorts of community noise had differing sensitivity levels. That is the key point in this seminal work. Schultz determined that 12.5 percent of the 300,000 people surveyed complained about noise irritation at 65 dB. That landmark work has been updated in a more confined aviation noise setting, and it has been determined that perhaps 20 percent to 40 percent of those surveyed complained of irritation at 65 dB, but acoustics scientists have opined that response to aviation noise may be influenced by factors other than just sound level itself.

However, the 65 dB noise level is between that of a large office and freeway traffic, and it is close to the level of normal interpersonal speech. The key here is Schultz’s recognition that human beings have varying sensibility to sound. Some folks are just much more sensitive than others. 


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