Detached doesn't solve everything, it just reduces it. Detached with some garden in between is good, until the drunken ranting at the BBQ starts, which is next to the fence and therefore as close as you can get.
Currently in a detached house but due to the ground in between being an extension of the driveways and paved front gardens, ie: concreted over, the sounds from both sides carry into ours. As a result I hear the kitchen floor being swept, toilets flushing, toilet lids banging, showers, shouting for Mummeeeeee, and shower doors slamming. Also clumping about on the decking which is attached to our fence and the wall, and balls banging on the decking. This is from inside the house and the vibrations carry through.
On the other side I hear any home repairs being done, carpets being laid, drilling etc. plus children thundering through the house. Scraping against the walls and furniture being dragged about too.
I know it would be much worse in a semi but sometimes it doesn't feel that way.
Even buying a house with a space between won't prevent someone building up to the boundary so it needs to be a substantial space otherwise you will, as I did, hear the radio and voices in the house next door after buying a detached house for peace and quiet.
Yes, I have also tried the countryside and ended up with children on mopeds riding between the houses, and playing on small (real) tractors next to the house on one side and a non stop barking dog on the other that would come down to our house especially to bark at us rather than his own house which was a long way off.
I despair of ever having a quiet home before I die.