Here's a low-tech approach: fill the window with staggered plastic straws. You don't get much of a view, however, and the airflow would be impeded. https://www

Here's a low-tech approach: fill the window with staggered plastic straws. You don't get much of a view, however, and the airflow would be impeded. https://www.researchgate.net/profile/Martin_Tenpierik/publication/336700023_Drinking_Straws_as_a_Broadband_Sound_Absorber/links/5dadc85ba6fdccc99d92851a/Drinking-Straws-as-a-Broadband-Sound-Absorber.pdf https://www.researchgate.net/profile/Martin_Tenpierik/public...