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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.

Harris Miller Miller & Hanson Inc. (HMMH) conducted sound insulation testing at 30 homes near Seattle-Tacoma International Airport (SEA) in March 2026 to measure how much aircraft noise penetrates indoors. The study found that none of the 30 homes exceeded the FAA's 45-decibel interior noise threshold required to qualify for sound insulation treatments under current federal policy. However, nine homes had at least one individual room where interior noise levels surpassed 45 decibels, suggesting those specific rooms could benefit from upgraded windows or doors.

In September 2025, acoustical engineers tested 29 homes near Seattle-Tacoma International Airport to measure how much aircraft noise penetrates indoors. The study found that none of the homes exceeded the 45-decibel interior noise threshold required to qualify for federally funded soundproofing treatments, though 10 homes had at least one room above that level. The findings are part of SEA's Repair and Replacement Program, which evaluates whether previously soundproofed homes need updated windows and doors.

In August 2025, acoustical engineering firm HMMH measured indoor noise levels at 31 homes near Seattle-Tacoma International Airport to assess eligibility for the airport's Sound Insulation Repair and Replacement Program. Testing found that only one of the 31 homes met the FAA's minimum threshold of 45 decibels interior Day-Night Average Sound Level required to qualify for full sound insulation treatment, while seven additional homes had at least one room exceeding that level. The study used FAA-approved methods, including a Boeing 737-800 aircraft noise spectrum, to calculate how much airport noise penetrates each habitable room with windows closed.

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.