The Tommy Sheridan perjury trial has heard that language used in a secret video alleged to be the former MSP was more like "Cartman from South Park".
Former SSP member Steve Arnott told the High Court in Glasgow a voice on the tape, claimed to be the politician's, had been made to sound like Mr Sheridan.
Mr Arnott also said Mr Sheridan rarely swore, unlike the voice on the tape.
Mr Sheridan and his wife Gail, both 46, deny perjury.
They are accused of lying during his successful defamation case against the News of the World in 2006.
The former Scottish Socialist Party (SSP) leader won £200,000 after the newspaper printed allegations that he had committed adultery and visited a swingers' club.
After the court action, Mr and Mrs Sheridan were charged with perjury.
The High Court in Glasgow has previously been shown a video that Mr Sheridan's best man George McNeilage sold to the News of the World for £200,000 after the defamation case.
The footage is said to feature Mr Sheridan admitting to Mr McNeilage allegations about his private life.
The former politician has repeatedly claimed he was not involved and that the film was concocted.
On Wednesday, the court heard from 48-year-old Mr Arnott, who was the regional organiser for the SSP in the Highlands.
He also served on the party's executive between 2000 and 2006, before joining Solidarity.
Mr Arnott was the latest defence witness to be asked about draft minutes from an emergency meeting of the SSP held following the publication of the News of the World article about a married MSP visiting swingers' clubs.
He said that he was not present at the meeting on 9 November 2004 but said that at a later meeting on 24 November no draft minutes were produced or ratified.
Mr Arnott was also shown a short section of a video tape allegedly showing Mr Sheridan incriminating himself.
Mr Arnott told Mr Sheridan, who is conducting his own defence: "I don't think it is you, Tommy.
"Obviously it does sound a wee bit like you but it is made to sound a wee bit like you.
"I have known you for 24 years. That is someone doing your public voice, your public persona, and doing it in a very rough way."
Mr Arnott said he felt the amount of swearing in the tape also indicated that it was not Mr Sheridan speaking.
He said he had heard Mr Sheridan swearing strongly perhaps "24 times in 24 years".
"That sounds like Cartman from South Park there," he added.
Meanwhile, one of the jurors in the trial was discharged by the judge.
The remaining 14 members of the jury will continue to hear the case.
Judge Lord Bracadale told the jury: "I have excused juror number eight from continuing to serve on the jury.
"I direct that the trial continues before the remaining 14 of you."
He said further directions would be given to the jury in due course.
Mr Sheridan denies making false statements as a witness in the defamation action on 21 July 2006.
His wife denies committing the same crime on 31 July 2006 after being sworn in as a witness at the civil jury trial.
The trial, before Lord Bracadale, continues.