The phrase "was back of" is an interesting one, as it contains a vowel sound that is somewhat elusive. Specifically, the "a" sound in "back" is actually pronounced more like an "uh" sound, which is represented in the International Phonetic Alphabet (IPA) as ə. This is known as the schwa sound and is often found in unstressed syllables. So, the correct IPA transcription for "was back of" would be /wɑz bək əv/.