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Acoustical Testing Results for SIRRPP — June 2026

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Port of Seattle
Noise Mitigation
SIRRPP HMMH Acoustic Testing

This technical memorandum from Harris Miller Miller & Hanson Inc. (HMMH), dated June 5, 2026, presents the results of interior sound insulation testing conducted in April 2026 for 30 homes near Seattle-Tacoma International Airport as part of the SEA Repair and Replacement Program. Acoustical engineers measured how well each room in these homes reduces outside aircraft noise, finding that only 4 of the 30 structures met the FAA's minimum threshold of 45 decibels of interior noise to qualify for sound insulation treatments. An additional 16 homes had at least one room exceeding that threshold, suggesting potential benefit from window and door upgrades, though current FAA policy does not require treatment based on individual room results alone.

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Technical memorandum from Harris Miller Miller & Hanson Inc. (HMMH), authored by Eric Cox, to Julie Kinzie at Seattle-Tacoma International Airport (SEA), dated June 5, 2026. Reports acoustical testing results for 30 residential structures in the SEA Repair and Replacement Program conducted in April 2026. Measures median interior Day-Night Average Sound Level (DNL) using Noise Level Reduction (NLR) methodology per FAA Advisory Circular AC 150/5000-9B and FAA Order 5100.38D AIP Handbook Appendix R. Exterior DNL of 70 dB assigned per 2018 Forecast Condition Noise Exposure Map (NEM). Four structures met the 45 dB median interior DNL qualification threshold; 16 structures had one or more habitable rooms above 45 dB. Addresses in SeaTac, Des Moines, Seattle, and Burien tested. Representative aircraft: Boeing 737-800. Equipment: HBK Model 2245 sound level meter, HBK Model 4231 calibrator, Mackie SRM450 loudspeaker. HMMH Project Number 03-12150.001.004.

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