Page 7 - Laqfoil Acoustic Catalog
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  controllability. As volume increases and predictability and controllability decrease, people are generally more likely to be annoyed, and thus stressed by noise. Other possible effects from noise, based on scientific studies include hearing loss, stress related diseases including hypertension (high blood pressure - both diastolic and systolic), compromises in immune system function, effects on the gastrointestinal system including digestive problems and ulcers, elevations in epinephrine, catecholamine, cortisol, and cholesterol, acute and chronic illness and sleep problems. Infant mortality, birth defects, and lower birth weight have even been linked to high levels of noise experienced by expectant mothers. With continued exposure, humans adapt to noise, but there is evidence that even people who have adapted can still suffer ill health effects from noisy environments. High intensity noise is associated with such complaints as headaches, nausea, instability, irritability, anxiety, sexual impotence, and mood changes. Various types of work become more difficult in the presence of various types of noise, with the result that performance and job satisfaction suffers. Among these types of work is learning,
so a noisy environment can have substantial effects on children’s classroom performance.
In environments with high ambient noise levels, a number of distinct auditory signals are presented simultaneously, and it becomes difficult for the human ear to distinguish or discriminate among them. This phenomenon is known as masking. If human speech is part of the background noise, our brains will automatically try to understand and follow it, so this is generally the most distracting type of noise. Many designers and builders today use a standard of 55 to 70 dB as acceptable for executive offices.
Studies have also shown that reducing noise decreases annoyance and increases satisfaction and performance in neighbors and students. These studies have repeatedly found that the difference people felt was more than expected for the difference in noise level. Other studies show that noise can reduce the value of a home by 1% for each decibel of excess noise.
Modern technology presents some solutions to this problem. There are two kinds of noise found in the interior environment, that which comes from within the room, and that which enters the room from outside of it, including other parts of the building, and the outdoors. Leading architects and designers use a number of techniques to
deal effectively with each type of noise. Sound energy can be reflected away from an area where it is not wanted using sound barriers, or
it can be absorbed, which involves converting into another
form of energy.
 A European directive dated June 25, 2002 defined noise pollution as “A serious problem of the modern world”. The public opinion research showed noise to be a key irritant in our daily lives. Research by INSEE (National Institute of Statistics and Economic Studies - France []), dated October 2002 showed that over 50% of Europeans consider the problem of noise pollution to be “Very serious”. This is not an unusual result among countries with high levels of urbanization.
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