'Real' open windows for buildings in tropical climates were studied. It focused on the window degree of openings and window orientation toward the noise source. The window type to be tested was top-hung shutter type only, based on multitasking duty between permitting airflow and noise blockage. The top-hung open window with a uPVC frame was tested of 3 orientations, i.e. perpendicular, oblique 60o, and 90o. The degree of openings was tested on 0o (closed), 5o, and 10o. Laboratory tests according to ASTM E90-09 were conducted to determine transmission loss (TL) & ASTM E1332-90 was referred to calculate the outdoor-indoor transmission class (OITC). Later, finite element analysis using COMSOL 5.0 was conducted to study the sound contour developed around the models. The study revealed that window orientation has little effects of noise reduction. Here, a 'real' open window is still not capable of blocking noise into the living spaces. However, when the open window was closed, perpendicular orientation offered higher OITC compared to the oblique ones. Thus, a perpendicular orientation is more recommended to reduce noise.