I bought a pair of the noise reducing curtains for a single window, and found that they blocked out only a small amount of ambient sound that was not bothering me in the first place. They are described as reducing noise by up to 40%. Maybe they do, but it did not seem to be the noise I hoped they would reduce, which is remote keyless entry horn honking and friends and car service drivers who honk their horns when they are picking someone up. The curtains look great, though, and I think the claim that they save on heating and cooling costs is likely true.
Years ago, I lived in an apartment with only two windows facing the street. A man would pick up someone next door early in the morning and honk his horn, and when I asked him not to, he retaliated by honking more. I bought some sound blankets used on movie sets to block out street noise, and they worked very well. There was a window facing the back, so I was able to get some natural light. I don't know if sound blankets and moving blankets are the same. With my recent noise issue, I've thought of buying more sets of noise reducing curtains and some sound blankets, and use them together with the sound blanket in the middle. But I plan to move and do not want to invest hundreds of dollars when this might not work. I've also thought about wooden shutters as a possible solution, but again, I would not want to invest that in my current apartment.
Last year I stayed at a bed and breakfast located on a busy street in Baltimore, in a room facing the street. There was a lot of keyless entry horn honking along the block, and a bus line ran along the street, and I was concerned about noise. As it turned out, every room in the house had double pane windows, and there was low key white noise from central air conditioning, so I didn't hear any street noise during the night.
SeekingSerenity, please let us know what you wind up doing, and include pictures, especially if the inserts work.