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From page 1...
... 1 1.1 Purpose of Report The primary purposes of this report, ACRP Report 152: Evaluating Methods for Determining Interior Noise Levels Used in Airport Sound Insulation Programs, are to discuss and clarify acoustical testing issues associated with airport sound insulation programs administered by the Federal Aviation Administration (FAA) and to provide proposals for improvement.
From page 2...
... 2 Evaluating Methods for Determining Interior Noise Levels Used in Airport Sound Insulation Programs With a program typically providing $25,000 to $30,000 of retrofit treatments at no cost to the homeowner (whose home is affected by airport noise) , the acoustical measurements take on added importance within the updated handbook (FAA Order 5100.38D: FAA 2014)
From page 3...
... Overview 3 – There are some rooms with results that are outliers and these findings are discussed in Section 4.1. – The mean and the median noise reduction should be computed, because comparing the results from the two statistics provides a check on the validity and stability of the NLR results.
From page 4...
... 4 Evaluating Methods for Determining Interior Noise Levels Used in Airport Sound Insulation Programs • Findings: – The NLR measured using the elevated-level exterior loudspeaker method is, on average, 0.5 dB lower than the overall average NLR. – There are some rooms with results that are outliers; Section 4.8 discusses this in detail.
From page 5...
... Overview 5 1.2.1.4 Interior Loudspeaker • Action: The research team conducted interior loudspeaker measurements in 10 homes in San Diego. In Boston, the research team conducted interior loudspeaker measurements in nine homes.
From page 6...
... 6 Evaluating Methods for Determining Interior Noise Levels Used in Airport Sound Insulation Programs • Findings: – Classical acoustic theory presumes that TL is the same in both directions (i.e., a wall performs equally whether the source of noise is inside of a home or outside of a home)
From page 7...
... Overview 7 acoustical instrument had a +0.5 dB error, it would not affect a relative measurement because the +0.5 dB would be added to both measurements and the difference would not be affected. Using the same instrument for an absolute pre-program qualifying measurement would incur the +0.5 dB in interior DNL.
From page 8...
... Notes: Meas. = duraon of the text; ppl = people; Inst.
From page 9...
... Overview 9 The elevated loudspeaker method requires a bucket truck with hydraulic lift to be used. Closely packed residences may not afford sufficient room to maneuver the truck to elevate the speaker for measurement.
From page 10...
... 10 Evaluating Methods for Determining Interior Noise Levels Used in Airport Sound Insulation Programs Based on the research team's findings, the aircraft flyover and exterior loudspeaker methods provide the best results. Sound intensity and indoor speaker methods show promise for future measurements, but additional research and standardization of the measurements is necessary.
From page 11...
... Overview 11 1.6 Acoustical Testing Best Practices Careful measurement protocol will minimize measurement uncertainties, particularly for the relative measurements. All measurement conditions should be carefully documented with field notes and photographs, with particular attention given to measurement locations.
From page 12...
... TestMethod Source Locaon Source Microphone Source Correcon ReceiverMicrophone Receiver Correcon Locaon (Reference) Location (Reference)
From page 13...
... Overview 13 5. Exterior microphones should be flush mounted where possible, rather than 1 to 2 m (3 to 6 feet)
From page 14...
... 14 Evaluating Methods for Determining Interior Noise Levels Used in Airport Sound Insulation Programs 4. It is not generally necessary to consider flanking transmission from air infiltration, because CTL need only be computed in the frequency range 50 Hz through 5 kHz where flanking effects are minimal.

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