Laserfiche WebLink
first two categories. Workers in industrial plants can experience noise in the last category. <br /> Unfortunately, there is as yet no completely satisfactory way to measure the subjective effects <br /> of noise, or of the corresponding reactions of annoyance and dissatisfaction. This is primarily <br /> because of the wide variation in individual thresholds of annoyance, and habituation to noise over <br /> differing individual past experiences with noise. <br /> Thus, an important way of determining a person's subjective reaction to a new noise is the <br /> comparison of the existing environment to which one has adapted: the so-called "ambient." <br /> In general, the more a new noise exceeds the previously existing ambient noise level, the less <br /> acceptable the new noise will be judged by the hearers. <br /> With regard to increases in A-weighted noise level, knowledge of the following relationships will <br /> be helpful in understanding this report. <br /> • Except in carefully controlled laboratory experiments, a change of 1 dB cannot be <br /> perceived. <br /> • Outside of the laboratory, a 3 dB change is considered a just-perceivable <br /> difference. <br /> • A change in level of at least 5 dB is required before any noticeable change in <br /> community response would be expected. <br /> • A 10 dB change is subjectively heard as approximately a doubling in loudness, <br /> and would almost certainly cause an adverse change in community response. <br />