By Alex Stevenson
Having a low voice improves politicians' chances of winning elections, US scientists have claimed.
The findings, published in the Proceedings of the Royal Society B journal, appear to vindicate the instinct of spin doctors that having a lower voice will help attract support - even if the candidate is female.
"What we have done is proven the folk wisdom that the structure of the human voice matters and actually shown that scientifically," co-author Professor Casey Klofstad of the University of Miami said.
Previous research on the topic had used recordings of past US presidents, but was weakened because there was a chance those participating could have been influenced by their political views.
This study, from a group of US-based academics, used 17 different recordings of men and women stating "I urge you to vote for me this November". The pitch of the sentence was then electronically made lower or higher.
Lower-pitched voices were preferred by the 83 students questioned 60% of the time.
Former prime minister Margaret Thatcher took vocal lessons to lower her voice in a bid to give her more gravitas. Nearly 40 years later that decision appears to have been vindicated by science - as well as her three general election victories, of course.
"Women are vastly under-represented in leadership positions across the globe," Prof Klofstad added.
"While gender discrimination is an obvious cause, our results suggest that biological influences between the sexes, and our responses to the differences, could potentially be another factor to consider."
Newspaper coverage of the story has failed to point out that, of Britain's recent prime ministers, the man with the deepest voice - Gordon Brown - has the least successful elections record.
His successor as Labour leader, Ed Miliband, was forced to deny that his operation to remove adenoids was unrelated to an attempt to prevent his voice sounding 'bunged up'. Observers noted that his voice appeared unchanged after the surgery was completed.