A grid of speakers fixed to a window can cut the noisiness of urban traffic in half, reducing the sound coming through an open window by up to 10 decibels
Source:
https://www.newscientist.com/article/2248486-noise-cancelling-windows-halve-traffic-sounds-even-when-theyre-open/?utm_campaign=RSS%7CNSNS&utm_source=NSNS&utm_medium=RSS&utm_content=home