The spelling of the surname "Rettenmund" can be tricky to decipher based on its pronunciation. Using the IPA phonetic transcription, we can break it down: /ˈrɛtənmʊnd/. The "r" sound is followed by a short "e" sound and a t sound. The second syllable contains a short "u" sound and the "n" sound. Finally, the word ends with a "d" sound. Therefore, despite its confusing spelling, "Rettenmund" is actually pronounced "RET-uhn-mund."