2005 General Plan - City Of Ventura

O U R H E A L T H Y A N D S A F E C O M M U N I T YNoiseNoise is generally defined as unwanted sound. Itseffects can range from annoyance to nuisancesto health problems. State law requires the City toidentify and address noise sources and establishprojected noise levels for roadways, railroads,industrial uses, and other significant generators.The Noise Contours map (Figure 7-3) is used tohelp guide land use in a way that minimizesexposure of residents to excessive noise.Vehicle traffic is by far the greatest source ofnoise affecting Ventura residents. Other sourcesinclude the Seaside Park raceway, the GrantPark shooting range, and railroad, commercial,and industrial activity. Homes, schools, hotels,and hospitals are considered sensitive receptorswhere excessive noise can interfere with normalactivities.Noise intensity is customarily measured on thedecibel scale, an index of loudness. Sounds asfaint as 10 decibels (dB) are barely audible, whilenoise over 120 dB can be painful or damaging tohearing (Table 7-1 shows some typical noiselevels). A sound 10 dB higher than another isperceived as about twice as loud. A 5 dB changeis readily noticeable, but a 3 dB difference isbarely perceptible.As shown in Table 7-2, normally acceptableoutdoor noise in residential areas may reach 65decibels. The Ldn label in the table indicates thatsound is averaged over time to account for thefact that sources like traffic or aircraft may causefluctuations of more than 20 dB over a fewseconds. CNEL refers to the fact that 5 dB isadded to noise after 7 p.m. and 10 dB added from10 p.m. to 7 a.m., when quieter conditions makesound more noticeable.The State Building Code requires an acousticalstudy whenever outdoor noise would exceed 60decibels at a proposed duplex, multifamilyresidence, hotel, motel or other attached dwelling.The study must show that the proposed projectdesign would result in interior noise levels of 45dB or less.Although future increases in traffic are notexpected to produce a significant change inperceived noise levels, other specific soundgenerators have been identified as problems inthe community. The policies and actions in thischapter look to reduce the exposure of people inVentura to these noise sources.Table 7-1. Typical Noise LevelsType of Noise or EnvironmentDecibelsRecording Studio 20Soft Whisper; Quiet Bedroom 30Busy Open-plan Office 55Normal Conversation 60-65Automobile at 20 mph 25 ft. away 65Vacuum Cleaner 10 ft. away 70Dump Truck at 50 mph 50 ft. away 90Train Horn 100 ft. away 105Claw Hammer; Jet Takeoff 200 ft.away120Shotgun at shooter’s ear 140August 8, 2005 2005 Ventura General Plan7-5