Scientists say that laughing at a good joke or when someone tickles us is instinctive, but crying when we're sad is something we learn from other people.
They say that only expressions of laughter and relief are instinctive, whereas other emotional outbursts need to be learned.
To find out which sounds are instinctive, a team led by Disa Sauter of the Max Planck Institute for Psycholinguistics in Nijmegen, the Netherlands, asked eight deaf and eight hearing individuals to vocalise nine different emotions, but without words. These included fear, relief, anger, hilarity, triumph, disgust and sadness.
Afterwards, Sauter and her colleagues played back the recordings to a panel of 25 hearing individuals, and asked them to match each utterance to an emotion.
It turned out that the only two easily identifiable emotional sounds made by the deaf participants were laughter and sighs of relief.
The panel found it easier to guess all the other emotions if the sounds came from the hearing individuals. Even screams of terror were much less obvious from those who were deaf.
"This means that for many kinds of emotional sounds, hearing the sounds of others is an important part of development for our sounds to be understandable to others," New Scientist quoted Sauter as saying.
Sauter suggests that laughter and smiling probably both evolved as important communication signals to help avoid confrontation by increasing empathy. he research team is presenting preliminary results as a poster at a conference held by the Acoustical Society of America next week in Cancun, Mexico.