In old days they hung tapestries in churches and castles to reduce sound reflections in a room. I have seen large moving blankets on walls and wool used the same way. Now you can buy modern scientifically designed sound panels that are designed by a team of engineers. I am an engineer, just electrical LOL. So this video demonstrates that simple cloth items do a great job with sound control. It would take a lot of work to make panels this way but you can buy moving blankets and other items that are similar that will reduce reflections and thus reduce noise on a larger scale. There are all kinds of things being used as YouTuber's are budget content producers. I spent over 1,000 just on sound and weather improvements on one generator. I spent a lot of time with sound and air flow monitoring to see what did or didn't make a difference. Why? Because I could hear it running next to my bedroom. Now I do not! Neither do my neighbors. So everything depends on the price you are willing to pay. I really don't want others knowing when my generator is running.