fɹʌm nˈaɪntiːnhˈʌndɹɪd ˈeɪɾi tˈuː, dˈɑːnəld ˈɛf. mək lˈiːn ˌʌndɚtˈʊk ɐ fɚɹˈɛnsɪklˈɛvəl ɪnvˌɛstɪɡˈeɪʃən ðæt aɪdˈɛntᵻfˌaɪd ɐ tˈoʊɾəl ʌv fˈaɪv dˈɪfɹənt dˈɪsk ɹᵻkˈoːɹdɪŋz dˈeɪɾᵻd nˈaɪntiːnhˈʌndɹɪd twˈɛnti sˈɛvən dˈæʃ twˈɛnti ˈeɪt ðæt klˈoʊsli ɐlˈaɪnd wɪððə pɹˈɪnsɪpəlz ʌv bˈɛɹdz fˈɑːnəvˌɪʒən pˈæʔn̩ts.
From 1982, Donald F. McLean undertook a forensic-level investigation that identified a total of five different disc recordings dated 1927-28 that closely aligned with the principles of Baird's Phonovision patents.