Have the sounds like nails running down a blackboard or knife on a glass made you cringe? These unpleasant noises are disliked worldwide and there’s a reason why we quail! From school, we all have been taught that we have five sense organs. What we don’t know is that the brain’s hidden senses are responsible for such responses. Various studies have been conducted on identifying the underlying reasons for this response and below are findings.
Why Do We Physically Respond To Unpleasant Sounds
1. The Amygdala–Auditory Cortex Interaction
A study was conducted on 13 individuals who were exposed to different types and frequencies of unpleasant sounds. The results were monitored through functional magnetic resonance imaging (FMRI).
The findings suggested that there was an increase in the interaction between the part of the brain that involves hearing (auditory cortex) and the part that perceives emotions (amygdala), upon the exposure to unpleasant sounds. It is a possible distress signal from the amygdala to the auditory cortex. The rate of interaction was also directly proportional to the degree of unpleasantness of the sound.
2. Certain Frequencies
Sound waves are measured in frequencies. Our brains are designed such that anything between 2000–5000 Hertz of frequency is considered as unpleasant. Certainly, human screams, baby cries, chalk/nails on a blackboard, ruler on a bottle, and fork on a glass fall into these frequencies. And a physical response to this stimuli is just a basic human tendency.
3. Survival Instincts
Some studies suggest that these unpleasant sounds are loosely related to survival instincts. The human brain perceives these sounds as a signal of distress or danger, which is the reason for a physical response. For example, people familiar with these sounds might save a crying infant sooner than people who aren’t attuned to these.
Surprisingly, in some people, who weren’t completely aware of these harsh sounds before, didn’t find them irritating when they heard them for the first time.