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Acoustical Testing Results for SIRRPP — August 2025

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Port of Seattle
Noise Mitigation
SIRRPP HMMH Acoustic Testing

This August 2025 technical report by Harris Miller Miller & Hanson Inc. (HMMH) presents the results of interior sound insulation testing conducted at 28 homes near Seattle-Tacoma International Airport (SEA) in July 2025. Using FAA-approved measurement methods, acoustical engineers tested every habitable room in each home to determine how much aircraft noise penetrates indoors, with a threshold of 45 decibels (dB) required for a home to qualify for sound insulation assistance. Of the 28 structures tested, only two met the 45 dB qualification threshold, while nine others had at least one room exceeding that level but did not qualify under current FAA policy.

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Notes

Technical memorandum from Harris Miller Miller & Hanson (HMMH), authored by Eric Cox and addressed to Julie Kinzie, reporting acoustical testing results for the Seattle-Tacoma International Airport (SEA) Repair and Replacement Program, July 2025. Testing covered 28 residential structures in Burien and SeaTac to determine median interior Day-Night Average Sound Level (DNL) values per FAA Advisory Circular AC 150/5000-9B and FAA Order 5100.38D Appendix R. Exterior DNL of 70 dB was assigned per the 2018 Forecast Condition Noise Exposure Map (NEM). Noise Level Reduction (NLR) was measured using HBK Model 2245 sound level meter and Mackie SRM450 loudspeaker with Boeing 737-800 representative aircraft spectrum. Results: two structures qualify (median interior DNL ≥ 45 dB); nine additional structures have individual rooms above 45 dB. Addresses tested include 13418 12th Ave S Burien, 20418 12th Ave S SeaTac, 12246 14th Ave S Burien, 20017 14th Ave S SeaTac, 11804 16th Ave S Burien, 11824 16th Ave S Burien. HMMH Project Number 03-12150.001.004.

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