It’s not like you can do a great deal about it, you are going to have to say hello to people – but the moment you do, you’ve given them an impression of what you’re like.

“From the first word you hear a person speak, you start to form this impression of the person’s personality, says Phil McAleer, a psychologist at the University of Glasgow, Scotland, who led the study.

In his experiment, McAleer recorded 64 people, men and women, from Glasgow, reading a paragraph that included the word “hello.” He then extracted all the hellos and got 320 participants to listen to the different voices and rate them on 10 different personality traits, such as trustworthiness, aggressiveness, confidence, dominance and warmth.

What he found was that the participants largely agreed on which voice matched which personality trait. One male voice was overwhelmingly voted the least trustworthy, “the sort of guy you’d want to avoid,” McAleer says. The pitch of the untrustworthy voice was much lower than the male deemed most trustworthy. McAleer says this is probably because a higher pitched male voice is closer to the natural pitch of a female, making the men sound less aggressive and friendlier than the lower male voices.

You Had Me at Hello: the Science Behind First Impressions – National Public Radio (5 May, 2014)

It’s not as if the impression people get is what you’re really like. You’ve made that impression and it is sticking. Have a read of the full NRP article and also listen to the radio station’s feature about it – plus test yourself and your own reactions to a series of voices.