The grande dame of elusiveness, Greta Garbo, was one of the most successful actors to make the transition from silent film stardom to sound. Her first speaking role was even publicised with the tagline "Garbo Talks!", where her husky voice was introduced to the cinema-going world. Apparently she refused voice coaching and her Swedish accent clearly didn't get in the way of her popularity.
However, things didn't pan out quite as well for stars like Polish born Pola Negri and Hungarian actress Vilma Banky. Both women had made names for themselves as onscreen femmes fatales during the silent era, but the advent of sound cut short both of their careers in Hollywood, due to their heavy accents.
Norma Talmadge was a hugely successful film star and one of the most highly paid actresses of the 1920s. She's even credited with starting the trend of celebrity handprints at Grauman's Chinese Theatre after accidentally stepping in wet cement outside the building. But when it came to talking, audiences found her Jewish Brooklyn drawl at odds with her sweet and cutesy onscreen persona. As one film historian put it: "sound proved the incongruity of her salon prettiness and tenement voice." Harsh enough.
Note the "The microphone - the terror of the studios" line, not to mention the snarky "You can't get away with it in Hollywood" positioned beside Norma's face. Lousy.
It seems that the dawn of the talkies also gave studios an excuse to cut troublesome stars loose, as Clara Bow's New York accent was thought to be the reason for her faltering career, although her constant clashes with film executives were really to blame. John Gilbert, who had become known as a dashing swashbuckler type was generally believed to have stopped acting because his voice didn't match his image. But it appears that, like Clara Bow, there were other reasons. According to his daughter, the tension between him and Louis B. Mayer escalated to the point that Mayer sabotaged Gilbert by making his voice recordings sound more high pitched than they truly were in order to end his career. The diabolical bastard!
So, Eastern European accents and devious studio heads aside, it's quite interesting how technology can have such a masive effect on a performer's career. I'm not sure there'd be an equivalent of it today really, other than film stars needing to be more gorgeous than ever with the introduction of HD broadcasting every pore and freckle on their faces. I suppose for now our over-exposed film stars are relatively safe from technological advances.