Voice and accent can make or break an election (just ask Ed Milliband, former leader of the UK Labour Party) because it's not always what you say, but how you say it. But what happens to politicians who develop a vocal disorder during their career? And what does this say about our attitudes towards speech in general?
Rosario Signorello and Didier Demolin, experts in phonetics and phonology at the Université Sorbonne Nouvelle, Paris, decided to find out. In a study presented at the Acoustical Society of America's 174th meeting, the pair discovered that vocal disorders do indeed affect a politician's perceived charisma and can even influence their electoral success – but probably not in the way you think.
Signorello and Demolin used speeches from two politicians who developed vocal disorders. The first was Umberto Bossi, a former rock singer, salesman, and laboratory technician turned leader of Italy's far-right political party, Lega Nord. The second was Luiz Inácio Lula da Silva, president of Brazil between 2002 and 2010 and the country's first leftist leader for almost half a century. In both cases, a speech disorder left them speaking lower with a narrower vocal range and lower pitch, making them more hoarse.
French listeners were asked to rate both politicians on a number of charismatic adjectives, using the Likert scale of agreement, before and after they developed vocal disorders. The fact that the listeners could not understand Italian and Portuguese meant they judged the speeches on vocal tone, not content.

"Before the stroke, people perceived Bossi as positive, enthusiastic, a very charming speaker, and when listening to his post-stroke voice, everything changed," said Signorello. "After the stroke, he had a flat pitch contour, a lack of modulation, and this was perceived as a wise and competent charisma."
And it turned out the French listeners preferred it that way. They were more likely to vote for Bossi after he had developed the vocal disorder. They had the same reaction to Luiz's disorder. The changes to the vocal chords made the politicians appear wiser and older.
"French people didn't want to vote for someone who was strong and authoritarian, or perceived as a younger version of the leader," said Signorello.
But this effect could be cultural. In an earlier study, Signorello found that French voters are drawn to politicians with medium vocal pitches (think: Francois Hollande) whereas Italians preferred a lower tone.
As Signorello pointed out, “There’s no single type of charismatic voice. The best speakers adapt their voices to their listeners, context, and culture. Charismatic leaders monitor audience reaction and possess the emotional intelligence to change their vocal delivery mid-speech to obtain the response they want.”