2000s, computer technology was used to restore the  video look to these episodes. In addition, other restorations and corrections  to the original broadcasts were made. (For example, the sound mix is altered  to remove background noise and accidental sounds like coughs in the studio,  in one episode a boom shadow was digitially removed). These restorations are  particularly apparent in the box sets Lost in Time and The Beginning which  compile surviving episodes from the early years of the series.