Noisy environments can significantly and negatively effect our bodies, and are a great villain to concentration, learning, and productivity in classrooms and offices. Headaches are one momentary symptom of noise. But staying exposed to very noisy places can bring greater problems such as hearing loss, lower concentration, high blood pressure, and even poor digestion. It can also trigger high levels of stress, sleep disturbances, mood changes, increased heart rate, and ringing in the ears. This is an invisible enemy and is often neglected in big cities with the noise of heavy traffic, demolition. and noisy equipment, such as generators and air conditioners. However, effective measures can be taken to avoid this unnecessary noise.
But to begin understanding acoustics, there are several important concepts and terms necessary to understand first. Acoustics are a very complex science, and architects often only give it due importance when it is not well resolved. The most commonly used unit of measure for sound is the decibel. Unlike units like meters or kilos, of which most people vaguely know the comparative length or weight, decibels are much more difficult to measure without a Sound Level Meter.
Graham Bell, a Scotsman whose surname was honored with the name of the unit, was the first to discover that the scale of sound perceived by the ear is logarithmic, like the Richter Scale, which quantifies the magnitude of an earthquake. This logarithmic scale of the sound intensity ratio adjusts to the intensity perceived by the human ear. Since we can hear a very wide range of sound intensities, the limit of audibility -- 10-12 watt/m2 -- is conventionalized as 0 decibels. Thus, there are sounds lower than that, but we cannot hear them. At a frequency of 1000 Hz, the human ear painlessly supports up to an intensity of 120 dB. Above this value, sounds are harmful and can irreversibly destroy the structures of the inner ear. Being exposed to sound levels above 90 dB for more than 4 hours is already highly harmful.
