It was just a short scene in a movie, in which a diminutive actor utters a few unscripted words to the orchestra leader, reciting a line that went down in history: “Wait a minute … you ain’t heard nothin’ yet.” But it was a scene that changed the entertainment world and heralded the dramatic arrival of sound to the movies.

Never again would audiences have to read “titles” to explain the action or translate the sweet nothings of lovers. In the space of just over an hour, the silent film was dead.

The moment occurred 90 years ago this weekend. The owners of rival studios had thought their competitors at the near-broke Warner Bros were going out of their minds. The idea of Warners featuring Al Jolson, the biggest star on the American musical stage, actually singing in an upcoming film was madness.

The producers laughed into their martinis as they smoked their cigars and contemplated picking up the spoils after Warner Bros filed for bankruptcy, as it surely would. Jolson plainly couldn’t survive either. Or could he? No. It was all a recipe for failure. For starters, The Jazz Singer, the story of the son of a synagogue cantor who breaks his father’s heart by going into showbiz, had to be a crazy choice.

Those rivals predicted trouble and drank and laughed some more. They could have had no idea how much trouble was coming. The arrival of sound brought disaster, bankruptcies and unemployment to a whole range of people – from silent movie stars to theatre cleaners.

The other studio heads had asked themselves what would happen if the machine controlling the records synchronising sound with action broke down? And those voices? Few stars sounded as good as they looked.

It had to be a flop. Didn’t it? Just a year before, Warners had made Don Juan, starring Douglas Fairbanks and Mary Astor, which didn’t exactly set the Hudson river on fire, despite sound effects like the clash of swords or chairs being thrown – all to the accompaniment of the New York Philharmonic.

The reason Sam Warner, the technical genius of the brothers, thought that adding a human voice would make all the difference was a series of shorts brought in as a late addition to the Don Juan programme. Giovanni Martinelli, principal tenor at the Metropolitan Opera, sang Pagliacci. The leader of the Philharmonic played his violin and Al Jolson sang When the Red, Red Robin (Comes Bob, Bob, Bobbin’ Along).

They were a secret success. The New York press hardly noticed, but audiences did – and loved them. What would be known as “the talkies” were coming out of the fairground.

It was Sam Warner’s idea to team up with the Western Electric company to buy its Vitaphone synchronising system. He had the faith that few others possessed, but sadly died of a mastoid infection of the brain the day before the hugely successful premiere of The Jazz Singer.

The youngest brother, Jack, had brought in Jolson – who said yes because The Jazz Singer was virtually his own life story. There was another reason – he was also promised a slice of the profits.

The brothers proved the naysayers wrong. Crowds outside the Warners’ theatre on Broadway that October evening were filmed waving hats as broad as the smiles on their faces. Acting with “blackface” – the then widely used makeup subsequently abandoned as racist – Jolson was a hit. The audience loved his plucky character. He might have been playing a stable boy on stage, but he told the man playing his boss to dust his own boots. On film, he was only expected to sing, not talk. But that wasn’t the way he was. The orchestra tuned up – and Jolson announced: “Wait a minute, wait a minute, I tell yer, you ain’t heard nothin’ yet.”

Jack and Sam realised that was not just unexpected, it was momentous. So they added a short scene in which Jolson plays the piano and tells his mother how great he is. That was the moment that killed the silent film. And then the problems began – for everyone in the industry except the Warners.

The other big studios were forced to convert their silent movies to sound – while their chiefs went about eating their words and ringing their bank managers. Smaller outfits, notably most of those in New York, went out of business. Cinemas all over the world closed their doors because their owners couldn’t afford the new equipment. Everywhere, piano players were fired. (No cinema had been without a musician in front of the screen, playing fast for a race across the western plains, and soft and smoochy for the inevitable love scenes.)

No one now wanted the people who wrote the “titles”. The theatre closures meant no work for the men who had turned the handles or controlled the reels for the old-fashioned projectors – to say nothing of those cleaners.

Most obvious casualties were the actors – people such as the silent heartthrob John Gilbert whose voice was pronounced too squeaky, although the story was that Louis B Mayer claimed he sacked him for being drunk.

There was something else that no one seemed to consider at the time: where would the world market for Hollywood’s output go? Now, films in English couldn’t be sold in other countries. There were two answers: films would be shot again and again, in French, German or Spanish, sometimes using the original actors such as Maurice Chevalier, who delighted his fellow countrymen by not having to speak English with an exaggerated French accent. Even Laurel and Hardy thought they had mastered phonetics and spoke in cod French or German.

Eventually studios realised that voices could simply be dubbed, which was not always a good idea.

The talkies, however, were hailed a good idea by the cinemagoers. As Jolson told them 90 years ago: “You ain’t heard nothin’ yet.”

Michael Freedland is the author of Jolson (Vallentine Mitchell) and a biography of the Warner Brothers