The spelling of the word "thorsen" can be explained using the International Phonetic Alphabet (IPA). The sound "th" (as in "thick") is represented by the symbol /θ/, while the sound "or" (as in "forest") is represented by the symbol /ɔː/. The sound "sen" (as in "hansen") is represented by the symbol /sɛn/. Combining these symbols, we get the IPA transcription of /θɔːsɛn/. Therefore, "Thorsen" is spelled with a "th" sound, followed by "or" and "sen".