Understanding how hearing works
Human senses are amazingly well-evolved and help us to navigate through the world. Hearing is one of the first senses we develop and even infants in their mother’s womb already perceive sound. But how does hearing actually work? How does the sound of a chord being struck on a guitar travel to our brains?
Sound travels in sound waves, this means that the guitar string creates invisible vibrations that travel in all directions, very much like waves spread out on a smooth water surface when you touch it lightly. When these waves reach our ear, the magic of hearing begins:
The sound waves that enter the ear canal eventually reach the ear drum, causing it and a number of small bones within the ear to flutter. These vibrations move further through the fluid in the cochlea, the inner ear which is shaped like the shell of a snail. The vibration of the fluid causes the tiny hair cells to detect movement which is changed into chemical signals for the hearing nerve. The hearing nerve then sends the information as electrical impulses to the brain, where the impulses are interpreted as sound.
What’s amazing about our hearing sense is that the brain is able to distinguish up to 20 different auditory signals in one second, making it much easier to perceive fine variations of sound than seeing the same details with our eyes.
So take a moment to acknowledge the miracle of your hearing sense.
Did you know?
- A sound pressure level of 120 dB is perceived as painful by humans.
- The lowest perceivable frequency is about 20 Hz, the highest – depending on the person’s age – 20 kHz at maximum.
- The highest sensibility of perception is at around 4 kHz.
- However, as great as our ears are, sound travels only at 343 meters per second, whereas light travels at 299,792,458 m/s.
- A cat’s hearing senses are about three times as well developed as that of humans.