It is described as "a clipped ‘uh’ sound used to emphasize certain words", for example, "We-UH-ell, the little things you say and do, make me want to be with you-UH-ou..." in his record of the song Rave On (1958).
[1] Edward Comentale asserts that Holly's hiccup technique comes from the southern tradition of "eefing".
A sharp break or silence is immediately followed by a loud burp, an extra 'supplemental' syllable.
[3][4] Michael Jackson started using the "vocal hiccup" in 1973, in the song "It's Too Late to Change the Time" on the G.I.T.
[5] Diana Ross claimed on The Today Show that Michael Jackson took the vocal hiccup technique from her.