According to this article in USAToday- it's pronounced "Cone" and not "Kohn"
http://www.usatoday.com/life/movies/2008-09-08-4087110751_x.htm
Great movies!
Franklin Coen's birth name is Franklin Robert Coen.
Joel Coen's birth name is Joel Daniel Coen.
Coen Tunnel was created in 1966.
Eleanor Coen was born in 1916.
Kevin Coen was born in 1947.
Shunter Coen was born in 1902.
Shunter Coen died in 1967.
Coen Cuserhof was created in 1908.
Noreen Coen was born in 1993.
Johnny Coen was born in 1991.
Martin Coen died in 1993.
Martin Coen was born in 1933.