3.13 Noise
Sleep Interference
Sleep interference is a noise concern because sleep is a noise sensitive human activity. Sleep
disturbance studies have identified interior noise levels that have the potential to cause sleep
disturbance. Sleep disturbance does not necessarily mean awakening from sleep, but can refer to
altering the pattern and stages of sleep (City of Solana Beach 1988). The California Department of
Public Health has identified 35-45 dBA as the noise level that could cause interruption of sleep
(County of San Diego 1980).
Human Reaction to Sound and Response to Changes in Noise Levels
People tend to compare an intruding noise with the existing background noise. If the new noise is
readily identifiable or considerably louder than the background or ambient, it usually becomes
objectionable. An aircraft flying over a residential area is an example.
Under controlled conditions in an acoustics laboratory, the trained healthy human ear is able to
discern changes in sound levels of 1 dBA, when exposed to steady, single frequency ("pure tone")
signals in the mid-frequency range. Outside of such controlled conditions, the trained ear can detect
changes of 2 dBA in normal environmental noise. It is widely accepted that the average healthy ear,
however, can barely perceive noise level changes of 3 dBA, whereas a 5 dBA change is readily
noticeable. A 10 dBA change normally is perceived as a doubling, or halving, of the noise level.
Sensitive Noise Receptors
Noise sensitive receptors are generally considered to be human activities or land uses that may be
subject to the stress of significant interference from noise. Land uses which are associated with
sensitive receptors often include residential dwellings, mobile homes, hotels, motels, hospitals,
nursing homes, education facilities, and libraries. Many jurisdictions recognize parks or recreation
areas as noise sensitive land uses. All of the receiver sites include recreational beach areas. The
recreational areas and activities and adjacent land uses are described in Section 3.6 of this EIR/EA.
The descriptions in subsection 3.13.3 below highlight the non-recreational noise sensitive uses that
would be exposed to noise sources included in the proposed action. These receptors are principally
adjacent to the receiver areas.
Regional Beach Sand Project EIR/EA
Page 3.13-3
99-69\SECT-03.13.DOC 9/24/02
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