The spelling of the phrase "sweetened kitty" can be explained through its IPA phonetic transcription. The word sweetened is pronounced as /ˈswiːt(ə)nd/ with the emphasis on the first syllable. The vowel sound in the third syllable is a schwa /ə/. On the other hand, kitty is pronounced as /ˈkɪti/, with emphasis on the first syllable and a short "i" sound in the second syllable. Overall, the spelling of sweetened kitty follows English phonetic rules and pronunciation patterns.