Misophonics have shown distinctive brain activity whenever they hear their trigger sounds, but authors say that hearing voices are another part of the brain's tuning in mechanisms.
Said lead author Dr. Ben Alderson-Day, from Durham University's Hearing the Voice project: "These findings are a demonstration of what we can learn from people who hear voices that are not distressing or problematic. It suggests that the brains of people who hear voices are particularly tuned to meaning in sounds, and shows how unusual experiences might be influenced by people's individual perceptual and cognitive processes."
The findings lend insight into the brain processes of voice-hearers and could help researchers find better ways to help people who find the voices troubling. The U.K. study involved people who hear voices -- or, auditory verbal hallucinations -- but otherwise have no mental health problems.
In it, participants underoing anMRI were asked to listen to what's known as sine-wave speech. It sounds a bit like bird chirping or alien-like noises, and most people are unable to detect any speech within it unless specifically told to listen for words. With training, however, people can typically understand simple hidden sentences within the noise, like, "The clown had a funny face".
Voice-hearers ID'd the hidden speech before being tipped off, and tended to notice it quicker than those with no voice-hearing history. The MRI showed the voice-hearers' brains were lighting up automatically to sounds that contained hidden speech compared to sounds that were meaningless.
The researchers say not all people who hear voices have schizophrenia, bipolar disease or some other mental health ailment. Indeed, between five and 15 percent of the general population have had an occasional experience of hearing voices, and as much as one percent have complex and regular voice-hearing experiences.
Said Co-author Dr. Cesar Lima from University College London's Speech Communication Lab: "We did not tell the participants that the ambiguous sounds could contain speech before they were scanned, or ask them to try to understand the sounds. Nonetheless, these participants showed distinct neural responses to sounds containing disguised speech, as compared to sounds that were meaningless. This was interesting to us because it suggests that their brains can automatically detect meaning in sounds that people typically struggle to understand unless they are trained."
The Hearing the Voice project seeks to understanding the experience of hearing a voice when no one is speaking and researchers hope to raise awareness among multiple disciplines of the phenomenon. This small-scale study was conducted with 12 voice-hearers and 17 non voice-hearers. More information about hearing voices can be found at the project's FAQs page. The study was published in the academic journal Brain.