The spelling of the word "retardating" can be confusing. The IPA phonetic transcription can help us understand why. The first syllable is spelled "re-" but pronounced with a schwa sound /ə/. The second syllable is spelled "-tar-" but pronounced with a hard "t" sound /t/. The third syllable is spelled "-da-" but pronounced with a short "e" sound /ɛ/. Lastly, the final syllable is spelled "-ting" but pronounced with a soft "t" sound /tʃ/. Overall, the word is pronounced: /ˌɹiː.təˈdeɪ.tɪŋ/.