Laserfiche WebLink
For highway noise environments,the average noise level during the peak hour traffic volume is <br /> approximately equal to the CNEL. <br /> The effects of noise on people can be listed in three general categories: <br /> a) Subjective effects of annoyance,nuisance,dissatisfaction; <br /> b) Interference with activities such as speech, sleep, and learning; <br /> c) Physiological effects such as startle,hearing loss. <br /> The sound levels associated with environmental noise usually produce effects only in the first <br /> two categories. Unfortunately,there has never been a completely predictable measure for the <br /> subjective effects of noise nor of the corresponding reactions of annoyance and dissatisfaction. <br /> This is primarily because of the wide variation in individual thresholds of annoyance and <br /> habituation to noise over time. <br /> Thus,an important factor in assessing a person's subjective reaction is to compare the new noise <br /> environment to the existing noise environment. In general,the more a new noise exceeds the <br /> existing,the less acceptable the new noise will be judged. <br /> With regard to increases in noise level,knowledge of the following relationships will be helpful <br /> in understanding the quantitative sections of this report: <br /> a Except in carefully controlled laboratory experiments, a change of only 1 dB in sound level <br /> cannot be perceived. <br /> b Outside of the laboratory, a 3 dB change is considered a just-noticeable difference. <br /> g J <br /> c) A change in level of at least 5 dB is required before any noticeable change in community <br /> response would be expected. <br /> id) A 10 dB change is subjectively heard as approximately a doubling in loudness, and <br /> would almost certainly cause an adverse community response. <br />