This is how voices communicate emotions
Howls of laughter, sighs of relief, and moans of delight are ways humans and animals alike communicate positive emotions. Why do we do it, how does it change as we get older and how does it vary by culture? That’s the subject of Roza Kamiloglu’s PhD dissertation, to be awarded this Thursday.
Where does your interest in the human voice come from?
‘I grew up in Turkey, and I was fascinated by all the sounds around me. The busy markets, energetic street life, and melodious calls of street vendors created a rich tapestry of sounds and emotions that have stayed with me. I became increasingly interested in how we communicate through our voice, especially through nonverbal expressions such as laughing, sighing, and shouting. When do we produce these vocal expressions and what happens when we do? My doctoral dissertation was a perfect fit; it allowed me to explore the role of vocal sounds in the communication of emotions.’
What are positive emotions in our voices?
‘We use our voice to express emotions even when we don’t use words. Laughing, shouting, and moaning are all examples of nonverbal voice sounds. But they also include characteristics of our voice while speaking, such as the rhythm, intonation, emphasis, and melody of our voice, called prosody. For example, when you are very excited, you speak faster and use a higher pitch, regardless of what you are saying. In several studies, we have now discovered that there is a range of positive emotions such as admiration, amusement, determination, excitement, and surprise that are expressed with different nonverbal voice melodies and prosody.’
Is there an evolutionary reason for positive emotions in the voice?
‘Yes, positive emotions in the voice contribute to social bonding, cooperation, and group formation, which are essential for survival and reproduction in group animals like humans.’
Do animals also make use of positive emotions in the voice?
‘Chimpanzees and bonobos, like humans, are known to make laughing sounds while playing. This strengthens social bonds and creates group formation. Some bird species also sing duets to strengthen pair bonds or indicate group bonding.’
How did you study that?
‘We compared voice sounds of different animal species. According to Darwin, emotional vocalizations have ancient, evolutionary roots and some mammals share these mechanisms. To test whether this hypothesis holds for human vocalizations, we collected vocalizations from humans as well as from chimpanzees. These vocalizations are produced in similar situations such as being tickled, having sex, threatening another individual, or being attacked by someone else. We then compared the acoustic structure of the human and chimpanzee voice in the same situation. Those structures turned out to be very similar.
We also asked people to listen to chimpanzee vocalizations and guess the chimpanzee's behavior based on them. Several studies showed that people were able to do this. That means people have innate abilities to recognize those sound structures.’
‘I find the range of emotions we can express with our voices fascinating’
Are there differences between cultures in the expression of positive emotions?
‘Yes. Laughter is a good example because everyone in the world has that in common. For my dissertation, I studied how Dutch and Japanese people can tell by the expression of laughter whether someone is from their cultural group or not.’
And are there differences between the expression of positive emotions throughout life?
‘Yes, babies laugh differently than adults. Research shows that a baby's smile resembles that of monkeys. In the course of early development, this smile becomes more and more like that of adults.’
What did you find most striking about your research?
‘How rich and powerful our use of voice is. Think of all the different forms of positive emotions in life: we are amused by a joke, in awe of a mountain range, and cheer when our favorite team wins the championship. I find it fascinating in and of itself that we can express all of that with just our voice.’
Roza Kamiloglu hopes to receive her doctorate on Thursday, April 6, at 1 p.m. for her dissertation Positive Emotions in the Voice: Towards an Ethological Understanding. Her defense will take place in the Agnietenkapel and attendance is free.
