To have a good communication in English first we have learn the pronunciations and English language is polysemy in nature. So learning the pronunciations through sound is apt in these kinds of situations.
→When we are listening to the pronunciations we might not be sure whether we heard ʊ or ə, ɒ or ʌ, s or z, etc., this is due to the lack of experience and the quality of the particular sound is poor. Hence reading phonetic transcriptions will make the phonemes clear as we will see the sound symbols of all the alphabets in a word