Berthelsen rhymes with:
adelson, bartleson, danielsen, danielson, donalson, eagleson, finkelson, fogelson, haralson, harralson, huddleson, jesselson, kittleson, mendelsohn, mendelson, mendelssohn, meselsohn, meselson, michaelsen, michaelson, michelsen, michelson, mickelsen, mickelson, mitchelson, nicholson, powelson, richelson, samuelson, tomilson, tumbleson
Berthelsen sounds like:
bartelson, bartleson, bertelsen, bertelsmann, bertelson