According to family lore, when my father age 13 and/or uncle Morris age 15 first attended public school, their teacher could not pronounce their last name (Goichmann).  The G sounded like "huh" and the ch was guttural sounding.  The teacher said she would henceforth call them Hoffman.  When they came home that day and told my grandfather.  He said OK we are now Hoffman.