Greener Skies – Appendix F: Noise

Proposed Arrival Procedures to Seattle-Tacoma International Airport F-1 November 2012 Appendix F NOISE AND ITS EFFECTS ON PEOPLE F.1 Background Information on Noise Metrics FAA’s Order 1050.1E addressing “Environmental Impacts: Policies and Procedures” specifies use of a measure of cumulative noise exposure caused by aircraft that operate over the course of an average day during a given year of interest. The metric is referred to as the Day-Night Average Sound Level (DNL). However, other measures are also helpful in explaining and understanding the elements of the noise environment that comprise the DNL around an airport. This appendix introduces the following acoustic metrics, which are the relevant elements that comprise DNL and provide a basis for evaluating and understanding a broad range of noise situations.  Decibel, dB;  A-Weighted Decibel, dBA;  Sound Exposure Level, SEL;  Equivalent Sound Level, Leq; and  Day-Night Average Sound Level, DNL. F.2 The decibel, dB All sounds come from a sound source – a musical instrument, a voice speaking, or an airplane as it flies overhead. It takes energy to produce sound. The sound energy produced by any sound source is transmitted through the air in sound waves – tiny, quick oscillations of pressure just above and just below atmospheric pressure. These oscillations, or sound pressures, impinge on the ear, creating the sound we hear. Our ears are sensitive to a wide range of sound pressures. The loudest sounds that we hear without pain have about one million times more energy than the…

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Call to order – Roll Call – Quorum Established – Land Acknowledgement We would like to acknowledge that our Agency operates in four present-day counties, which are the traditional lands of the Coast Salish people, past and present. This acknowledgement does not take the place of authentic relationships with indigenous communities in our jurisdiction and [...]