Definitely work in the mid-higher frequencies and over all "dampen" sound If you think these will block sound, they wont, but they do a fantastic job at "dampening" sound so it's less noticeable or immediate sounding. It's never going to block low end sound, but I'd say the 15bd is about right for mid-high frequencies. They are quality curtains, and have a decent weight to them. I'm very happy with the affect it made to my studio door from outside noise, and visa versa.

Think this worked for us We needed to reduce the sound between a toddler waking up in the night and an adult who had to get up to work early. Seems to have helped. Very heavy, so had to make a special bracket for them to hang on but noise seems to have been reduced so happy.

No regret Even if it remains relative, there is a real noise gain the quality of the curtain is superb. iI is worth the price without worries, do not expect a miracle but a slight noise gain, the curtain is of superb quality the fabrics are very beautiful . I really don’t regret. I recommend.