The vocal communication of different kinds of smile

The present study investigated the vocal communication of naturally occurring smiles. Verbal variation was controlled in the speech of 8 speakers by asking them to repeat the same sentence in response to a set sequence of 17 questions, intended to provoke reactions such as amusement, mild embarrassment, or just a neutral response. After coding for facial expressions, a sample of 64 utterances was chosen to represent Duchenne smiles, non-Duchenne smiles, suppressed smiles and non-smiles. These audio clips were used to test the discrimination skills of 11 listeners, who had to rely on vocal indicators to identify different types of smiles in speech. The study established that listeners can discriminate different smile types and further indicated that listeners utilize prototypical ideals to discern whether a person is smiling. Some acoustical cues appear to be taken by listeners as strong indicators of a smile, regardless of whether the speaker is actually smiling. Further investigations into listeners’ prototypical ideals of vocal expressivity could prove worthwhile for voice synthesizing technology endeavoring to make computer-simulations more naturalistic.