Researchers have analysed the most popular girls and boys names from the last decade and found male names are more likely to contain broad sounding vowels such as Jack or Tom, while female names tend to comprise smaller sounds such as Emily and Mia. The British team suggests this trend developed because stronger sounding names were perceived as more masculine while names with softer sounds were viewed as more feminine. "The origins of names may vary but this study suggests that there is an association between the size of the sounds in first names and the sex they are associated with," said study leader Benjamin Pitcher from Queen Mary, University of London. Dr Pitcher and his colleagues reviewed the vowel sounds, or phonemes, of the top 50 names given to 15 million babies in Australia, the UK and the US between 2001 and 2010. It covered 30 per cent of births in those countries for that period. Each name was classed as large or small sounding based on the sound of the vowel in the syllable that was most emphasised. They found parents were 1 1/2 times more likely to give a son a name with a larger, harsher sounding vowel - such as the "o" in Noah - than a daughter. Girls were more likely to be christened with a name that had smaller sounding vowels, such as the "i" in Olivia. Dr Pitcher said larger sounding vowels pulled the tongue down the back of the mouth, creating more airspace that released lower frequency sounds, which were associated with masculinity. In contrast smaller sounding vowels forced the tongue forwards and upwards in the mouth resulting in higher frequency sounds. ""Parents may not actively seek a large or small sounding name for their child, but instead are likely to show an unconscious preference for either a more masculine or feminine name to suit their child's sex,"" said the authors, whose findings were published in the journal PLoS One. Dr Pitcher said culture also played a significant role in baby name trends - parents often copy popular names, especially those given to celebrity children - but their research suggested their was an underlying trend based on masculine and feminine sounds. "This is an interesting example of how biological evolution can influence human culture," said study co-author Alex Mesoudi, from Durham University. Examples of popular boys names with larger sounding vowels: Jack Lachlan Cooper Noah Tom Examples of popular girls names with smaller sounding vowels: Isabella Olivia Mia Lily Ella