image: Two types of judgements (certainty, honesty) are based on a single acoustic signature: high pitch that falls at the end of the word, intensity in the middle of the word, and fast speech rate. Above: certainty, below: honesty.
Faster speech rate, greater intensity in the middle of the word, and falling pitch at the end of the word: that is the prosody[1] to adopt if one wants to come across as reliable and honest to one's listeners. Scientists from the Science and Technology for Music and Sound laboratory (CNRS/Ircam/Sorbonne Université/Ministère de la Culture)[2] and the Perceptual Systems Laboratory (CNRS/ENS PSL) have conducted a series of experiments[3] to understand how we decide, based on the voice, whether a speaker is honest and confident, or on the contrary dishonest and uncertain. They have also shown that this signature was perceived similarly in a number of languages (French, English, Spanish), and that it is registered "automatically" by the brain: even when participants were not judging the speaker's certainty or honesty, this characteristic sound impacted how they memorized the words. Prosody consequently conveys information on the truth-value or certainty of a proposition. Scientists are now trying to understand how speakers produce such prosody based on their intentions. This research was published on 8 February in Nature Communications.