TAI is a weighted average of the time kept by over 450 atomic clocks in over 80 national laboratories worldwide.
tˌiːˌeɪˈaɪ ɪz ɐ wˈeɪɾᵻd ˈævɹɪdʒ ʌvðə tˈaɪm kˈɛpt baɪ ˌoʊvɚ fˈoːɹhˈʌndɹɪd fˈɪfti ɐtˈɑːmɪk klˈɑːks ɪn ˌoʊvɚɹ ˈeɪɾi nˈæʃənəl lˈæbɹətˌɔːɹiz wˈɜːldwaɪd.