AFTER a year dabbling in radio, I listen to other people’s voices with a new ear. It is like suddenly seeing a black and white world in technicolour. The right voice can make a plain person irresistible. The wrong one can kill beautiful words stone dead. Some people you could listen to for hours reading weather reports. Others are so grating they make you leap for the off button. Julia Gillard’s nasal rasp is a case in point. Tony Abbott’s occasional reediness another.

Radio people are cocky about the bulging instruments in their throats, making them slightly preposterous in large groups. But at radio awards nights you see more than the usual number of ugly men with very attractive partners, and when they open their mouths you know why – those deep melodious voices are like treacle in the dark.

Take Russell Crowe. As an actor he left me cold, until he uttered those immortal words in Gladiator: ‘My name is Maximus Decimus Meridius, commander of the Armies of the North, General of the Felix Legions… Father to a murdered son, husband to a murdered wife.’ Swoon. That voice hooks you right under the heart; transforming its owner in an instant from hirsute, fleshy-faced dolt into a love god.

Voice is a vastly underestimated component of charisma. Pitch, timbre and resonance combine to express the essence of personality, more effectively than body language or the words we utter. It is as distinctive as a fingerprint, green eyes or red hair.

Christopher Hitchens wrote that being ‘struck dumb’ by the cancer that eventually killed him was worse than going blind or deaf. Losing the ability to speak was ‘the amputation of part of the personality. To a great degree, in public and private, I ‘was’ my voice.’

People unconsciously judge you based on the rumblings of your larynx, assessing in a split second your power, social dominance, attractiveness, sex appeal, trustworthiness, and even fighting ability. Men with deep voices are more successful in business and politics, run larger companies, earn bigger salaries and appeal more to voters. The lower the pitch, the more authoritative they seem, according to scientists at the University of Glasgow who found people can form an impression of someone’s personality based solely on the 390 millisecond sound of saying ‘hello’. A deeper voice in a man is perceived as strong, attractive, healthier and more masculine. Since low pitch correlates with sexual allure, the male larynx grows up to seven times larger than the female’s at puberty, and hence the adult male voice is regarded as a secondary sexual characteristic, more important even than bulging pectorals.

For women it’s more complicated.

Men find higher-pitched voices in women more attractive, because they sound feminine and subservient. But women with deeper voices are perceived as more socially dominant and authoritative in, say, business. This dichotomy has led to a peculiar fashion among young women known as ‘vocal fry’. Perfected by Kim Kardashian and Katy Perry, it is a sort of croaky drawl, particularly at the end of a sentence, created by a languid fluttering of the vocal chords. Said to have started on Wall Street, it’s a way for women to have a deep voice but retain a cool, feminine edge. Nevertheless, the female voices deemed most sexy in opinion polls don’t show signs of this scratchy affectation. The mellifluous Angelina Jolie and Scarlett Johansson usually score, while the velvet baritones of George Clooney, Morgan Freeman and Sean Connery are among the sexiest male voices.

A good politician knows the power of voice, and none more so than Bob Carr. Say what you like about his woeful political legacy, he was his state’s longest serving premier, in no small part due to the well-modulated baritone he took such care to cultivate. I watched him once walk out of a radio studio and detour into the newsroom, not to talk about breaking stories but to swap earnest voice maintenance tips with the broadcast pros.

Carr had voice coaching and acting lessons to enhance the smooth James Earl Jones-esque resonance of his vocal chords. In his latest book he describes his voice as ‘masterly’; it went a long way to disguising his natural nerdiness. ‘Your authority begins with your voice,’ he once said, taking his cue from politicians such as Barack Obama who have perfected the persuasive power of their vocals.

But most Australian politicians seem to prefer the authenticity of the uncultivated voice. Ironically, Gillard’s unionist twang is regarded by fellow Adelaidians as an acquired affliction.Rudd’s voice had a sonorous gravitas, which was undermined, after frequent exposure, by peevish undertones. Malcolm Turnbull has a deep oak-like monotone, a quality which vocal scientists say makes men irresistible to women; the steady tone is associated with power and confidence. Cue Clint Eastwood. Julie Bishop has a seductive, honeyish quality to her voice which is pitched lower than most women’s, giving her a commanding aura. Scott Morrison, too, has one of the better Australian political voices; deep, well-modulated, with a hint of gravel.Joe Hockey’s voice is pleasantly low-pitched but sounds oddly young.

Judging by old recordings, Bob Hawke used to have a high-pitched nasally voice but, at 84, it has mellowed into a rich, roguish croak. John Howard concedes Hawke had the better voice but his own, too, has improved with age, now the boyish squeak has acquired velvety bass notes.

It’s hard to get past Bill Shorten’s speech impediment, which has him say ‘wiv’ instead of ‘with’, but the intrinsic quality of his voice is unobjectionable. Of medium pitch, it is not authoritative or masterful but nor is it whiny or unpleasant. That is, until he starts yelling at union rallies, when he reverts to ‘jockey voice’ and demonstrates the puniness of his instrument.

Tony Abbott has a similarly medium-pitched voice, with a pleasant timbre under tight control, but it becomes light and overstretched when he tries to make himself heard over Question Time bellows. Nature has endowed neither leader with a born-to-rule baritone, but how might a Bob Carr cadence shift the opinion polls? Voice is a secret weapon for politicians and they’re mad if they don’t exploit it.