![]() ![]() Even if decibel numbers look fairly close, the actual sound difference associated with the two numbers is really much greater. ![]() The numbering system for decibels is a little complicated. Whether the damage is permanent or not depends on the decibel level, the length of time, and how often the ears are subjected to the injurious sound. Scientists say, in fact, that sounds above 85 dB may lead to at least temporary hearing loss. ![]() That is about the loudest sound level our ears can take at close range, although anything over 120 dB can start to cause pain and potential damage. At the other end of the scale, the roar of jet engines can register up to 120 dB while firing machine guns top out at 140 dB. The smallest audible sound (near total silence) for humans usually correlates to 0 dB, and soft whispers are rated at a relative increase of about 15 dBs. The loudness, or intensity of sound is described in relative units called decibels (abbreviated dB), named after the American inventor of the phonograph and telephone Alexander Graham Bell. You will learn that sound travels through the air as a wave, or a traveling vibration as air molecules bump into each other. You might be surprised at what you discover.īefore you begin your project, you will want to do some background research on sound and hearing. You will then compare the results from the various sites to see if those noisy spots are really as loud as they seem and if the supposedly quiet zones are truly an acoustical haven for the ears. You will use your phone's microphone and a sensor app to measure the range of noise and sound in your neighborhood, home, school, and surroundings. But how softly can someone speak and still produce a sound that can be heard? On the other hand, how loud is too loud for our ears? At what level does sound become harmful to our hearing, and is the damage temporary or does it have long lasting effects? In this project, you will discover the answers to these questions and more in your experiments and research. There is an old adage that claims if you really want someone to pay attention, then whisper. ![]()
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