A more recent digital analysis of the tape claims to reveal the "a" may have been spoken but obscured by static.
ɐ mˈoːɹ ɹˈiːsənt dˈɪdʒɪɾəl ɐnˈæləsˌɪs ʌvðə tˈeɪp klˈeɪmz tə ɹᵻvˈiːl ðə "ˈeɪ" mˌeɪhɐv bˌɪn spˈoʊkən bˌʌt əbskjˈʊɹd baɪ stˈæɾɪk.