Community Response to High-Energy Impulsive Sounds An Assessment of the Field Since 1981 (1996) / Chapter Skim
Currently Skimming:
3 Development of a Dosage-Response Relationship
3 Development of a Dosage-Response Relationship
Pages 17-32
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 17... ...
Fundamental understanding of the source of community response to impulsive noise exposure remains rudimentary at best, since only a 17
|
From page 18... ...
It is difficult to argue on the basis of empirical evidence, however, for a strong causal relationship between any metric of noise exposure and community response. The fact that useful estimates of community response may be made for some purposes over a 20 dB range from about Ldn = 55 to 75 dB does not mean that annoyance is uniquely caused by a time-weighted average of sound levels.
|
From page 19... ...
The arguments advanced in the rest of this chapter lead to two alternate means for predicting the annoyance of impulsive noise exposure. Until a better understanding of the origins of community response to impulsive noise exposure arises, both of these interim approaches should be viewed as expedients rather than as tacit theories about the origins of annoyance.
|
From page 20... ...
The use of C-weighting provides a reasonable measure of the low-frequency sound pressures associated with high-energy impulses of the type under consideration; and 2. The use of sound exposure level instead of peak sound level meets the need to incorporate a measure of signal duration, since perception of noisiness increases with signal duration.
|
From page 21... ...
It justifies assignment of equal weight to duration and level in calculating sound exposure levels of individual noise events; and
|
From page 22... ...
Schomer's laboratory and controlled-exposure studies suggest the possibility of achieving greater accuracy of prediction of community response to high-energy impulsive noise through a level-dependent summing of CSEL values of individual impulses into a variant form of CDNL. As described in Appendix B
|
From page 23... ...
23 a' 1 be ·_4 o a' Cq o x 3 a' ·_4 C)
|
From page 24... ...
Similarities of this sort in response to disparate noise exposures are attributed to difference in response biases among the residents of the two communities. Civic action groups, political or media attention, and other factors can make the residents of the quieter community more likely to describe themselves as highly annoyed even by relatively low noise exposures.
|
From page 25... ...
Individuals describe themselves as highly annoyed when their reactions to noise exposure exceed a fixed value of a criterion (A) for reporting annoyance.
|
From page 26... ...
is the constant 61.1 chosen to minimize the variance of the set of available field observations of the annoyance of high-energy impulsive noise exposure. Figure 8 shows a relationship developed from the rationale of this discussion that can be used for environmental assessment purposes to predict the prevalence of annoyance associated with exposure to high-energy impulsive noises (Method 1~.
|
From page 27... ...
Sound exposure and annoyance units would also double with each doubling in numbers of events of the same sound level. Equal trading between number of events and event magnitude (sound exposure or annoyance units)
|
From page 28... ...
For blast sounds, two incoherent events at the same sound level produce double the C-weighted sound exposure (+3 dB) and double the number of equivalent annoyance units.
|
From page 29... ...
The term LA= c - 94 relates the equality level to the sound exposure level of Y4 did, which corresponds approximately to the sound exposure for a sound pressure of 1 Pa (pascal) and a duration equal to the reference sound-exposure duration of 1 s.
|
From page 30... ...
(T (19) where ~ is the slope of the relation between the CSEL of a high amplitude impulse sound and an equivalently annoying control sound and LA=C is the equality point (the point at which the impulse sound CSEL and its equivalently annoying control sound ASEL are equal)
|
From page 31... ...
Under typical field conditions, the standard deviations of actual distributions of sonic booms propagating over long ranges at different times of day are probably closer to the higher values plotted than to the lower values. Figure 12 shows the relationship between the available social survey data points and the dosage-response relationships for the level-dependent summation method.
|
From page 32... ...
fit to social survey results for impulse noises. 10 Events/Day
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.