Researchers found that the loudness in humans’ thoughts, or how we imagine speaking in our minds, influences how we judge real external sounds.
The findings of the study were published in the journal Nature Human Behavior. Tian Xing and Bai Fan from NYU Shanghai, David Poeppel and Teng Xiangbin from NYU, and Ding Nai from Zhejiang University conducted the research, according to Medical Xpress.
“Our thoughts’ are silent to others –but not to ourselves, in our heads—so the loudness in our thoughts influences the loudness of what we hear,” said Poeppel, a professor of psychology and neural science.
Likewise, Tian explained that after a human imagined speaking in his mind, the actual sounds he hears will become softer. The louder the volume of imagery, the more delicate perception will be. He further explained that this happens because imagery and perception activate the same auditory brain areas and the prior imagery activates the auditory areas once. This process leads to responding less as the same brain areas are needed for perception.
In the study, the scientists asked the participants to think of a word and say it very loudly or very quietly to themselves. When the participants just merely shouted something in their heads, they did not say anything loud.
Then, the team played a tone out loud and asked the participants to rate how loud the noise was on a scale of one to 10. They evaluated the responses of the participants and the results showed that when someone thinks with a loud internal voice, the external noises sound quieter, according to Metro USA.
Poeppel further explained by citing an example. If someone asked you to shout “cat” in your head, then played a sound afterward, you will imagine that external noise to be soft due to the sound in your head is very loud. Vice versa, if you believe saying something softly, then you will imagine the external sound to be louder.
The finding of the study could help in understanding or researching the causes of such speech disorders such as stuttering and mental conditions like schizophrenia. It will also give insight on how the human brain works and how it interacts with the external world. It also suggests that loud noises in the world are competing with the sounds in the humans’ heads, according to Poeppel.