Sound engineers have managed to construct the speech former US president John F Kennedy was about to make before he was assassinated in 1963.

Key points: Sound engineers looked at John F Kennedy's pitch and energy in past soundbites to reproduce the lost speech

Sound engineers looked at John F Kennedy's pitch and energy in past soundbites to reproduce the lost speech JFK was to make the speech the same day he was assassinated

JFK was to make the speech the same day he was assassinated He planned to use the speech to talk about America's strength

According to British newspaper The Times, engineers managed to pull 116,777 sound units from 831 of JFK's speeches and radio addresses to bring the text to life.

The digitally-created speech, known as the Trade Mart speech, was originally due to be made on 22 November 1963 before the 35th president of the US was shot dead.

It was recreated as part of The Times' "JFK: Unsilenced" project.

JFK was riding in a motorcade in Dallas and had been preparing for the next presidential campaign when he was killed by Lee Harvey Oswald.

JFK was to address an annual meeting of the Dallas Citizens Council.

John F Kennedy addresses joint session of congress two years before he was killed. ( NASA: John F Kennedy Presidential Library and Museum )

The Times teamed up with text-to-speech developer CereProc and Irish company Rothco and recreated JFK's voice reading the 2,590-word speech by analysing past speeches.

To make the speech more lifelike, the developer focused on pitch and energy from his previous soundbites.

It took eight weeks for the speech to be reproduced.

BBC reports lead voice engineer Chris Pidcock told Radio Scotland they used artificial intelligence to determine how his pitch changed when delivering past speeches.

"That was a big part of the project because we didn't want his intonation to be a boring and standard intonation," he said.

"We took his existing speeches and material and we cut it up into tiny pieces and stitched it back together in a new speech.

"JFK had a really unique speaking style and getting his intonation correct was something that we had to spend some time on."

Former US president, John F Kennedy, photographed in 1963. ( John F Kennedy Library )

JFK talks about America's world standing, security

In the 20-minute speech he never got to make, JFK talked about the country's strength and security.

"For this nation's strength and security are not easily or cheaply obtained, nor are they quickly and simply explained," he said.

"There are many kinds of strength and no one kind will suffer.

"Overwhelming nuclear strength cannot stop a guerrilla war. Formal pacts of alliance cannot stop internal subversion. Displays of material wealth cannot stop the disillusionment of diplomats subjected to discrimination.

"Above all, words are not enough. The United States is a peaceful nation. And where our strength and determination are clear, our words need merely to convey conviction, not belligerence. If we are strong, our strength will speak for itself. If we are weak, words will be of no help."

ABC/AP

