[villagetinker]

Sound does not travel well through concrete, so your problem is probably at the windows. You could try sound reducing drapes. If I may be so bold, what is the source of the sound, would it be possible to reduce at the source?
When we first moved here I found the highly reflective sound of the tile floors and drywall very annoying. My wife refused to use area rugs. I did research on 'sound reducing paints' and these do NOT appear to be a suitable choice.
You house already has significant sound reduction, several inches of concrete, and then a few inches of insulation.
If you can provide additional details, perhaps all of us can provide additional ideas.
Hope this helps.