Jim did not wear headphones, nor did anybody else at RCA Studio B in those days. One of their old time engineers told me he set up speakers "out of phase" (don't ask...it's too technical!) and did a playback and Jim sang to it. His vocals were recorded on three track equipment with his voice generally in the center. So they could mute that on the original "take" in places where they wanted him to sing English lyrics during playback. The challenge was that Jim had to try to match the same tonal quality in his voice with the original recording.

They captured Jim's re-sung English lyrics and then substituted them in a remixed version of the song so it would have more commercial appeal to English only audiences.