Agenda - 11-22-2004-c1 - Laserfiche WebLink

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25 Environmental Sound Page 10 ,4ttaehment 3 Special characteristics of the noise that make it especially irritating, Outdoor sound level when offending noise is not present, People are more accepting ofnoises that occur only in daytime or only in winter, They acceptnoises they aze accustomed to and were present when they bought their property, It helps if they believe the producer ofthe noise is doing everything reasonable to controlit It also helps ifthe noise is notunpleasant sounding, An important factor is whether the noise is much louder thanthe sound present in the neighborhood without the noise. The most significant result ofthe EPA community reaction studies is thatwidespread complaints and possibly legal action usually occur when the average level of noise from a single source is regularly more than 5 dB above the avefage level of other sounds in the community, Vigorous community action results for differences of 20 dB, Perceptions are important. The attitude of'the source owner as perceived by the complainant is often the second most important factor. Sometimes complainants have a misconception of the true attitude of the source owner.. Other studies have identified other perception factors that are very, much related to community reaction and annoyance, These include whether the complainant perceives the noise as Unnecessary or unnecessarily loud, A threat to personal health or safety, A threat to economic investment (property value), or Beyond his control, or if The complainant believes he is being ignored or treated unfairly, Special characteristics in the way the noise sounds must be considered, Some sounds are more irritating or dif3icultto ignore than others. The acoustical designers of vehicles, appliances, and other products today spend most oftheir effort on "sound quality." It is recognized that people not only expect quiet, but expect a quality of sound, The most common sounds with irritating characteristics are those containing tones, or repetitive impulses, or information content. Atone is a concentration of noise at a single frequency, Examples of sounds with strong tones are sirens, horns, bells, whistles, and certain types of transformers, pumps, and fans. These produce shrill, whining, or humming sounds which get attention. These aze the types of sound that are helpful as warning devices, but are irritating to tistento continuously, A repetitive impulsive sound is one which is made up of repeated pulses of sound. Examples are power presses, hammering sounds, and gunshots, Such sounds usually must be several decibels quieter in measured sound levelthan "normal" sounds to produce a s'urrilar amount ofannoyance, A five decibel penalty has often been used, However, recent research indicates that highly impulsive sound such as gunshots must produce a time-average level 12 dB less than more common sounds for the same annoyance. Loud or amplified