The sound insulation of partially open double glazing

The sound reduction index has been measured in the laboratory for partially open sliding window units. The object was to test the feasibility of achieving a moderate degree of sound insulation whilst retaining natural ventilation. Assuming source spectra for aircraft and traffic noise and using the measured SRI's, the sound level difference across a window has been calculated in terms of dB(A). It is concluded that partially open double glazing is about 10 dB(A) better than partially open single glazing, and that double glazing can be opened as much as 100 mm and still be as effective against aircraft noise as closed single glazing.