James Chal Up Nik To Richard Aram Bru 03061992 Re Integrated Noise Model DNL 0001

This letter is in response to a request from you in our telephone conversation last Wednesday. You asked me to provide you with comments on the appropriateness of the Ldl metric for rating aircraft noise in neighborhoods surrounding Sea-Tac Airport and to discuss the data that is used for input to the Integrated Noise Model (INM) that is used by the FAA and others to produce the Ldn contours for airports, such as Sea-Tac. These two items are discussed below. NOISE METRICS The purpose of any noise rating scheme is to associate a single number with the noise being evaluated which, when compared with other noises, will rank order the noises in turns of human perceptions of loudness or annoyance. This is not a simple task. Noise is "Unwanted sound." Therefore, not only the physical properties of the noise must be considered, but also many factors that depend on the nature of the noise and the way in which humans respond to it must be considered. This topic is the basis of a much research and has been vigorously studied since the invention of the microphone. A good reference on the subject can be found in my book1. The principal physical properties of a noise that play a part in the subjective evaluation of lts annoyance are: • sound intensity • frequency (’pitch) distribution • fluctuations of the above over a given time period rJ } Evaluating the Noises of Transportation, The University of Washington Press, Seattle, 1969. _suP Mr.…

Open full document

Upcoming Events

PSCAA Advisory Council Meeting Agenda
Add to CalendarMWednesday Mar 11, 9:00am - 11:35am
1904 3rd Avenue, Suite 105, Seattle, WA 98101
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 [...]