Prior to the invention of pitch correction, errors in vocal intonation in recordings could only be corrected by re-recording the entire song (in the early era of recording) or, after the development of multitrack recording, by overdubbing the incorrect vocal pitches by re-recording those specific notes or sections. By the late 70s, engineers were fixing parts using the Eventide Harmonizer H49. Prior to the development of electronic pitch correction devices, there was no way to make "real time" corrections to a live vocal performance in a concert (although lip-syncing was used in some cases where a performer was not able to sing adequately in live performances).