This study was carried out by Professor David from the Pennsylvania State University, they selected more than 200 men from California and the University of Pennsylvania for the test. The goal was to analyze their voices in the different situation. The results showed that there was direct relation between the frequency range of the sound and the number of girlfriends they had. People with smaller sound change of frequency range seem to be more welcomed by the opposite sex while people with undulating sound were not like the former when referred to charm. Some Hollywood actors with monotonous sound could become the example: the sound of George Clooney and Clint Eastwood is not outstanding, however, the monotonous voice not only failed to make them become famous, but also make them more attractive. The study was published on the medical journal of sex files.

Daily Mail quoted the words of David which said it is not the sound itself to play the role, but the attractive force in the meantime. Researchers believe that monotone voice is a symbol of strength, independence and domination. When the speaker feels anxious or afraid, the frequency of speaking becomes faster, when he has the offensive implied meaning, the frequency of sound will slow down. The monotone voice is relatively stable, which show the strong ability of control the situation. Perhaps it is this power to win the opposite sex. David said: "Women seem to care more about the identity of men, they seem to prefer to high-status men." Except the factor of tone, manly words like I am stronger than others are more eye-catching in the eyes of the opposite sex.

A website has conducted a survey to prove that the voice play an important role in attracting the opposite sex. 73% of people have requested the voice of the other half to be attractive, 58% of people said person's character can be judged by reading the works of Shakespeare. Many people say they often judge people’s character by a person described in their own words and tone. So this website launched voice information services so that people can truly hear each other's self-introduction. 84% of the respondents said they will ultimately decide whether to contact other by the voice information. However, once the romantic relationship is established, voice messages would no longer have a significant role, replaced by a handwritten message.