What do you do when trying to catch a barely perceptible sound? Like many, you probably close your eyes. This reflex seems logical because it eliminates visual distractions. However, a recent study upends this idea: in a noisy environment, keeping your eyes open actually allows you to better distinguish faint sounds. This discovery challenges a widely held intuition.
To test this hypothesis, scientists from Shanghai Jiao Tong University conducted an experiment, the results of which were published in
The Journal of the Acoustical Society of America. Participants listened to sounds played with background noise, adjusting the volume to be able to perceive them. They repeated the task under different visual conditions: with eyes closed, open on an empty screen, and then while looking at a static image or a video sequence related to the sound heard.
Study participants listening to faint sounds despite background noise. They perceive these sounds better when they can open their eyes and watch videos or images matching the sounds.
Credit: Yu Huang The results surprised the team. Contrary to expectations, closing one's eyes made detecting faint sounds drowned in noise more difficult. Conversely, seeing a video associated with the heard sound clearly improved auditory sensitivity. Thus, relevant visual information helps the brain extract the target signal from the surrounding racket.
To understand this mechanism, the researchers measured the participants' brain activity. When the eyes are closed, the brain adopts an operational mode where it filters incoming information more intensely. This filtering, sometimes too zealous, can eliminate not only the parasitic noise but also the target sound. On the other hand, appropriate visual stimulation keeps the auditory system anchored in the external environment, which facilitates the separation between the useful signal and the noise.
It is important to note that this observation does not hold true for quiet places. In calm conditions, closing your eyes can indeed help in perceiving very subtle sounds. However, as most of our living spaces are lively, keeping your eyes open proves to be a more advantageous tactic for hearing well.