The "identity element" is the shuffle in which nothing changes.
ð ɪ WORD_BOUNDARY aɪ d ɛ n t ɪ t i WORD_BOUNDARY ɛ l ɪ m ə n t WORD_BOUNDARY ɪ z WORD_BOUNDARY ð ə WORD_BOUNDARY ʃ ʌ f ə l WORD_BOUNDARY ɪ n w ɪ t̠ʃ WORD_BOUNDARY n ʌ θ ɪ ŋ WORD_BOUNDARY t̠ʃ eɪ n d̠ʒ ɪ z WORD_BOUNDARY