Early pioneers of this technique were Les Paul and Buddy Holly. Originally, a pair of single-track (or ' mono') tape recorders were used to produce the effect later, multitrack tape machines were used. Use of this technique became possible with the advent of magnetic tape for use in sound recording. As early as the 1950s, it was discovered that double tracking the lead vocal in a song gave it a richer, more appealing sound, especially for singers with weak or light voices.