Jim Haas, who sang backup on the The Wall studio album and the 1980-81 Wall tour, died earlier this year. He started out with a "psychedelic rock" band from Billings, Montana called The Frantics. He played keyboards and sang the high tenor. The Frantics toured with the Jeff Beck/Jimmy Page Yardbirds in 1966. Haas sang backup on countless albums during the 1970's and 80's and sang lead on the theme song for the Happy Days television series. He also sang backup on the The Wall Live in Berlin in 1990 along with Stan Farber, Joe Chemay and Jon Joyce.

I found out he passed away from an article about the release of a Frantics album that was recorded in 1968 but wasn't released until last month. There are some samples of the album on YouTube:

https://www.youtube.com/watch?v=BPLQvgkfaz0

His recorded voice lives on...