Scientists have learned that when humans (and frogs, too, I bet) hear unpleasant sounds, the auditory cortex of the brain and an area of the brain called the amygdala interact together to produce a negative response. The auditory complex processes sound while the amygdala is responsible for processing emotions such as fear, anger, or pleasure. "When humans hear an unpleasant sound, the amygdala heightens our perception of the sound. This heightened perception is deemed distressing and memories are formed associating the sound with unpleasantness."
You may remember from your science or biology class that sound is a form of energy. That energy causes air to vibrate and, thus, creates sound waves. Hearing involves the conversion of sound energy to electrical impulses. Sound waves from the air travel to our ears and are carried down the auditory canal to the eardrum. When you really think about it, hearing is a pretty complex sense!
An article in the Journal of Neuroscience states that sounds with frequencies in the 2,000 to 5,000 hertz (Hz) range are unpleasant to humans. That range, we are told, is when human ears are most sensitive. Humans with good hearing can hear sounds that range from as low as 20 Hz to as much as 20,000 Hz. Based on their research work, here are the ten most annoying sounds for most humans, in order of their unpleasantness: 1. Knife on a bottle, 2. Fork on a glass, 3. Chalk on a blackboard, 4. ruler on a bottle, 5. fingernails on a blackboard, 6. a female scream, 7. angle grinder, 8. breaks on a cycle squealing, 9. a baby crying, and 10. electric drill.
"Listening to these sounds induced more activity in the amygdala and auditory cortex than did other sounds. When we hear an unpleasant noise, we often have an automatic physical reaction. This is due to the fact that the amygdala controls our flight or fight response" which means that when humans hear these sounds, the brain sends signals to prepare for possible danger. So what are the least unpleasant sounds? The study found that applause, laughing, thunder, and water flowing were the participants top four.
So let's get back to the sound of our own voice and why most of us don't like it. Our own voice sounds different to us when we speak because the sounds vibrate internally and are transmitted directly to our inner ear. As a result, our voice sounds deeper to us than it does to others. But when we hear a recording of our voice, the sound is transmitted through the air and travels down the ear canal before reaching our inner ear. "We hear this sound at a higher frequency than the sound we hear when we are speaking. The sound of our recorded voice is strange to us because it is not the same sound we hear when we speak."
Thanks for stopping by today and I hope you'll join me again tomorrow when my wise friend and teacher, The Dharma Frog will visit for my weekly life lesson. One thing about Dharma, he always has something important and helpful to say. Until we meet again, I wish you a pleasant day.