Hearing things? Some auditory hallucinations might be caused by this phenomenon

It's an experience that you've probably had at least a few times; you could have sworn someone called your name but when you turned around, no one was there. You're not alone in that, either. In fact, it's estimated that as much as 15% of the general population has experienced some level of auditory hallucination, whether it be hearing your name or other distinct sounds that indicate something is there when it's not. A smaller percentage of individuals deal with this on a routine basis, and the common conception is that the frequency of these experiences indicates some level of psychosis. And while some individuals suffering from psychosis do experience auditory hallucinations, there are many who experience auditory hallucinations unrelated to any mental health issues. A new study has taken to examining these types of individuals to uncover the hows and whys of this phenomenon.

The study, published in the neurology journal Brain, concentrated its efforts on individuals without psychosis to examine the hallucinations without the interference of medication or any other associated mental health conditions. Researchers set out to test the predictive processing theory, a hypothesis that suggests the human brain is always attempting to make patterns out of what it encounters to better understand and predict the world around it. This theory is often used to explain why we sometimes see faces in inanimate objects – our brains are working so hard to interpret our surroundings that they may actually get ahead of reality. The study extrapolated this theory to propose that maybe those who experience auditory hallucinations simply have brains that are more susceptible to this pattern-making.

The study examined 12 participants who admitted to often hearing sounds that were not present and 17 who did not. All were told the nature of the study, but not specifically what researchers were looking for. While their brains were being scanned for activity, participants listened to two 20-minute rounds of sine-wave speech. Sine-wave speech mimics the frequencies of normal speech through a series of robot-like "beeps" and "boops". Subjects were played both intelligible and unintelligible (segments of intelligible audio with distortions layered over top) clips and were instructed to listen for and identify certain target sounds. After listening to various rounds of sine-wave speech, participants were asked if and what words they heard.

After the first round, 75% of the individuals who commonly experience auditory hallucinations identified that they found speech present in the clips they were played, while less than half of participants in the other group came to the same conclusion. Both groups used areas of their brains that were typically associated with such a task, but the voice-hearing group also activated additional ones that are most often associated with focusing attention, suggesting that their brains worked harder to understand what they were hearing. Before the second trial, all participants were primed to identify hidden speech and both groups performed similarly, suggesting that those who do not experience auditory hallucinations could hear voices when instructed to, but those who do have a natural inclination toward it.

Though a small sample size, which behooves further research, these findings certainly support the predictive processing theory and demonstrate that auditory hallucinations may not be produced from within our brains, but from the ways in which we attempt to process external stimulation. Further, some individuals may be more hypersensitive to this manner of neural processing than others. While this is encouraging evidence, the struggles of those who suffer from auditory hallucinations remain a very critical and complicated issue. There are numerous support groups for those who suffer, which help to eradicate the common assumption of psychosis and aid those afflicted in better managing the condition in everyday life. Still, even these well-intentioned groups have come under scrutiny for their approaches to handling the issue.

What is ultimately clear above all is that more information, research and awareness around auditory hallucinations is essential, for both those who deal with it chronically and those who do not. Because we have all encountered this experience in some form, it's hopefully easier to understand how our brains can create these sounds and also the struggles of those who confront them more frequently. It's no secret that our brains are so complex that they often function far beyond our understanding, so unlocking even a small shred of our brains' dynamics goes a long way in comprehending and managing its place in our lives.