David A. Collings PE
Sound Quality and PsychoAcoustics:
The human perception of sound can involve many factors that reach far beyond the physical science of acoustics. The interpretation that we place upon the complex audio inputs to our brains can trigger emotions that range from euphoria to rage. We can be soothed by a babbling brook, inspired by a symphony concert or driven frantic by a dripping faucet.
Some of the qualitative aspects of sound are well understood. The harmonizing of tones whose frequencies combine with numerical compatibility is basic to every type of music, although the human taste in the rhythmic elements of music can reflect wide cultural and social differences. Sounds can trigger widely different responses depending upon their context and we have learned to interpret and classify sounds in many subtle ways. As with art, the human brain can make associative sub-conscious leaps that can color our responses to sound patterns in unexpected and sometimes irrational ways.
Our acoustic environment generally has both foreground and background components. Foreground noises are those that demand some kind of attention. Speech, warning signals, music, etc. all trigger a response at some level in our conscious brain. These sounds are superimposed on an inevitable background of random noise that, to a large extent, is filtered from the sounds that we hear. When we classify background sounds as noise pollution, this is often an indication of the quality of the sounds rather than their measurable levels. Varying, intermittent or impulsive sounds can be more intrusive than a steady continuous noise that we can easily ignore. This factor makes the writing and enforcement of noise ordinances much more difficult. Noise control projects are more likely to be initiated in response to complaints than by the need to comply with state or national standards.
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