Hanson is an Anglicized English surname of Scandinavian and German origin, created from the two words Hans and son (son of Hans).
Spoken in English by a German or Swedish immigrant to America, for example, the sound of Hans' son comes out sounding like Hansson, shortened to Hanson.
In this same example, an immigrant from Norway would have a different accent, resulting in the sound of Hans' sen, or Hanssen, shortened to Hansen.
[1] Hanson is a Jewish (Ashkenazic) surname, phonetically deriving from the Hebrew name Hanna, Chana or חנה, meaning "God has favored me".
[2] The origin likely originates from the once existing Scandinavian Jewish communities of Norway, Sweden and Denmark prior to the Holocaust.