This is a Windows-only program that simulates sound in a room – both sounds inside the room and those coming from outside. You can download it (free) using the link below. To install, unzip the file and double-click on SoundScapeSetup.msi. You may be asked to install a DotNet framework during the process – just follow the prompts and you should be fine.
You can watch a video describing how the program works:
or here are links to: