Differences between Outdoor and Indoor Sound Levels for Open, Tilted, and Closed Windows

Area of Science:

• Environmental Health
• Acoustics
• Building Science

Background:

• Accurate indoor noise exposure assessment is vital for health effect studies.
• Current models often estimate outdoor noise, leading to uncertainty in indoor exposure.
• Limited field data exists on indoor-outdoor noise level differences and sound damping factors.

Purpose of the Study:

• To quantify the sound level difference between indoor and outdoor environments.
• To investigate how window positions affect indoor noise levels.
• To identify building characteristics influencing outdoor noise damping.

Main Methods:

• Conducted field measurements in 102 Swiss residences exposed to road traffic noise.
• Recorded sound pressure levels outdoors and indoors (living room, bedroom) for open, tilted, and closed window scenarios.
• Collected data on window orientation, floor, room type, and building sound insulation properties.

Main Results:

• Median outdoor-indoor sound level differences were 10 dB(A) for open, 16 dB(A) for tilted, and 28 dB(A) for closed windows.
• For open/tilted windows, room position, type, volume, and building age were key factors.
• For closed windows, outside sound level, window frame material, gaskets, and window count were significant.

Conclusions:

• Window status significantly impacts indoor noise reduction.
• Building characteristics play a critical role in modulating outdoor-to-indoor sound transmission.
• Findings improve accuracy for indoor noise exposure assessment in health studies.