London: Scientists have created a new digital audio platform that can change the emotional state of a person by modifying the tone of their voice while they are talking, to make them sound happier, sadder or more fearful.
New results show that while listening to their altered voices, participants' emotional state change in accordance with the new emotion.
"Previous research has suggested that people try to manage and control their emotions, for example hold back an expression or reappraise feelings," said lead author Jean-Julien Aucouturier from the French National Centre for Scientific Research (CNRS).
"We wanted to investigate what kind of awareness people have of their own emotional expressions," she said.
In an initial study using a novel digital audio platform, participants read a short story aloud while hearing their own altered voice, sounding happier, sadder or more fearful, through a headset.
The study found that the participants were unaware that their voices were being manipulated, while their emotional state changed in accordance with the manipulated emotion portrayed.
This indicates that people do not always control their own voice to meet a specific goal and that people listen to their own voice to learn how they are feeling.
"The relationship between the expression and experience of emotions has been a long-standing topic of disagreement in the field of psychology," said Petter Johansson, one of the authors from Lund University in Sweden.
"This is the first evidence of direct feedback effects on emotional experience in the auditory domain," said Johansson.
The emotional manipulations were created by digital audio processing algorithms that simulate acoustic components of emotional vocalisations.
For example, the happy manipulation modifies the pitch of a speaker's voice using pitch shifting and inflection to make it sound more positive, modifies its dynamic range using compression to make it sound more confident, and modifies its spectral content using high pass filtering to make it sound more excited.
The researchers believe this novel audio platform opens up many new areas of experimentation.
"Previously, this kind of emotion manipulation has not been done on running speech, only on recorded segments," said Aucouturier.
Co-author Katsumi Watanabe from Waseda University and the University of Tokyo in Japan considers that the platform could be used for therapeutic purposes, for example for mood disorders by inducing positive attitude change from retelling affective memories or by redescribing emotionally laden events in a modified tone of voice.
It may also help enhance the emotional impact of Karaoke or live singing performances, or maybe to alter the emotional atmosphere of conversations in online meetings and gaming.
The study was published in the journal PNAS.