Boy slowly fades into another dimension

This was a young adult book that I read in the mid eighties. A boy starts being ignored by people around him until he just slowly fades away into another dimension. The real world that he left can vaguely be seen (I think). He finds other things around him that have also left the "real world" - a towel, a whole house, and even another person. He becomes friends with that person until one day when that person disappears. At the end of the book he returns to the real world with no recollection of being gone but has a cassette tape in his pocket that he recorded his adventure on.

I remember this from another thread. It turned out to be Displaced Person by Lee Harding. Does that look right to you?

Thank you so much for reading and responding. It is exactly right and I am so excited to get a chance to find and read it again.

Glad to help! It's piqued my interest too, I'm going to have to to get it through interlibrary loan. :)