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

Abstract

Noise exposure prediction models for health effect studies normally estimate free field exposure levels outside. However, to assess the noise exposure inside dwellings, an estimate of indoor sound levels is necessary. To date, little field data is available about the difference between indoor and outdoor noise levels and factors affecting the damping of outside noise. This is a major cause of uncertainty in indoor noise exposure prediction and may lead to exposure misclassification in health assessments. This study aims to determine sound level differences between the indoors and the outdoors for different window positions and how this sound damping is related to building characteristics. For this purpose, measurements were carried out at home in a sample of 102 Swiss residents exposed to road traffic noise. Sound pressure level recordings were performed outdoors and indoors, in the living room and in the bedroom. Three scenarios—of open, tilted, and closed windows—were recorded for three minutes each. For each situation, data on additional parameters such as the orientation towards the source, floor, and room, as well as sound insulation characteristics were collected. On that basis, linear regression models were established. The median outdoor–indoor sound level differences were of 10 dB(A) for open, 16 dB(A) for tilted, and 28 dB(A) for closed windows. For open and tilted windows, the most relevant parameters affecting the outdoor–indoor differences were the position of the window, the type and volume of the room, and the age of the building. For closed windows, the relevant parameters were the sound level outside, the material of the window frame, the existence of window gaskets, and the number of windows.

Self-Reported Sleep Disturbance from Road, Rail and Aircraft Noise: Exposure-Response Relationships and Effect Modifiers in the SiRENE Study

“…From this value, a window position-dependent attenuation was subtracted to get the estimated indoor exposure level. Sound attenuation terms for open (10 dB), half-open/tilted (16 dB), and for closed windows (28 dB) were obtained by measurements carried out in a separate validation study in a subsample of 102 survey respondents [29].…”

Associations of Various Nighttime Noise Exposure Indicators with Objective Sleep Efficiency and Self-Reported Sleep Quality: A Field Study

“…Temporal resolution was set to one second. The indoor measurements were compared with the concurrently conducted outdoor measurements, and an algorithm was developed to derive the A-weighted attenuation factor in dB based on the correlation and the offset of these parallel measurements [42]. Finally, estimated indoor levels for analysis were obtained for each study participant by subtracting the individual attenuation factor from the outdoor measurements, taking into account the preferred window position for the season when the data were collected, as indicated in the baseline questionnaire.…”

Nighttime environmental noise and semen quality: A single fertility center cohort study

“…For the possible relocation of the patients during the exposure period, we believe future studies considering the information would be needed. If the extent of exposure misclassification occurs independent of health status and thus is non-differential, effect estimates are likely to be underestimated [44]. Furthermore, as we used semiannual data, some of the measurements might have been done after the sperm tests.…”