The X Factor was forced to cancel its live public vote on Saturday night after sound issues left contestants with distorted robotic voices during the primetime ITV programme.

Two performances were ruined by the glitch, which left major sound issues during songs by Danny Tetley and Anthony Russell as well as distorting the voices of the X Factor judges, with some viewers comparing the experience to listening to Daleks.

An on-screen message told viewers “we are sorry for the temporary interference in sound” and confirmed that the vote would not take place as planned, with viewers instead allowed to vote for their favourite on Sunday night’s programme.

The programme is usually broadcast live but was pre-recorded to enable judge Robbie Williams to catch a flight to South America, where he is due to play a long-arranged gig in Chile. He is due to be replaced by Nile Rodgers for the coming episodes.

A spokesperson for ITV apologised for the situation and said they were investigating why this happened. The lack of premium-rate phone call income will be a financial hit for the broadcaster.

The X Factor, now in its 15th series, has struggled in the ratings in recent years. At its peak it regularly attracted well over 10 million viewers but recent episodes have been around the 4 million mark.

Meanwhile BBC One’s Strictly Come Dancing – shown earlier on Saturday evenings – has regularly broken the 10 million barrier.