Carstensen is a Danish surname with a complex spelling. It is pronounced [ˈkɑːstənsən] using the International Phonetic Alphabet (IPA). The first syllable of the surname is pronounced as "car" with a long "a" sound, while the second syllable features a soft "t" sound and an "en" ending. The final syllable is pronounced as "sen" with a long "e" sound. The spelling of Carstensen reflects Danish pronunciation and is a testimony to the beautiful complexity of the Danish language.