Science is getting closer to using instruments to accurately determine brain states and/or affect them.
One recent study deals with the cruder outlines of tone of voice— happiness, sadness, or fear—showing that the way we process our own tone of voice is probably the same as the way we process other people’s tones of voice.
From the abstract:
…our result reinforces the wider framework of self-perception theory: that we often use the same inferential strategies to understand ourselves as those that we use to understand others. (Covert digital manipulation of vocal emotion alter speakers’ emotional states in a congruent direction)
Additionally, this study shows that we are affected by our own tones of voice without being consciously aware of that. If you want to cheer up, speak more cheerfully and it will affect you as well as others, though obviously this can be taken too far.
The other study, which was conducted on people undergoing neurosurgery, shows that
…continuous auditory representations… could be accurately reconstructed from measured neural signals. (Reconstructing Speech from Human Auditory Cortex)