What are people Why do we hear

Listen

Who can hear has to feel

A piece of music can move you to tears. Soft voices have a calming effect, while persistent snoring drives some people to white heat. The emotional effect of sounds has a developmental background.

Our hearing warns us of impending dangers. Originally they were predators, today it is mainly road traffic. Unlike the eyes, the ears perceive alarm signals even during sleep.

Advertising has long since made use of the emotional significance of sound: sound designers are working on designing razors, for example, in such a way that they sound particularly powerful and powerful. Chips or corn flakes are mixed with substances that create a crispy crack in the mouth. The ear eats too.

What happens when you listen

As emotionally as we react to sounds: what the ear picks up is nothing more than fluctuating air pressure. Sound waves collect in the auricle, enter the ear canal and the eardrum. This starts to vibrate.

Behind the eardrum are the ossicles named after their shape: hammer, anvil and stirrup - the smallest human bones.

The hammer senses the vibration, the anvil passes it on, the stapes transfers it into the inner ear. This is where the cochlea lies: a spiraling bone space that contains a watery fluid called perilymph.

The stapes compress this fluid. The resulting traveling wave excites the basilar membrane and the hair cells connected to it. The movement of these hairs is translated into nerve impulses that create the auditory impression in the brain.

See with your ears

Hearing helps us with orientation. It's not for nothing that we have two ears: a sound from the left reaches the left ear sooner than the right. The time shift is minimal - it is less than a thousandth of a second.

The brain locates the source of the noise in a flash: We immediately feel whether a sound is coming from the left or the right.

The blind, in particular, know how complex the process of hearing is. Not only do they feel their way forward with their stick, they also listen to its sound. In this way, they always know where they are in a tunnel - the echoing sound of the strike of a stick provides information.

Blind people also make use of another amazing hearing benefit: the so-called "cocktail effect". Everyone knows it from parties: however big the babble of voices may be - if anyone whispers about us, we hear it immediately.

Blind people hear the brakes just as quickly from the noises of the approaching train: They are right between the doors. Before a door opens, the blind man has spotted it.

The sense of hearing - efficient and sensitive

Our sense of hearing is the most differentiated of all five senses. The ear is more sensitive, more precise and also more efficient than our eyes. It can differentiate between ten octaves and reacts to sound waves, i.e. changes in air pressure in the frequency range between 16 and 20,000 hearts.

The sense of hearing enables us to distinguish up to 400,000 tones and even the direction from which they are coming.

At the same time, our ears are very sensitive. Any part of the ear can be damaged, or be harmed. The most common are defects in the inner ear. The fact that our ears function properly is not as natural as we often assume: around 600 children are born deaf in Germany every year.

According to the German Association of the Deaf, around 80,000 deaf people live here. An estimated 14 to 16 million people are hard of hearing and around three million people suffer from constant ringing in their ears, known as tinnitus.

The physics of hearing

Physically speaking, sounds are sound waves. The unit frequency indicates the number of vibrations of a sound wave per second, which is expressed in Hertz or Kilohertz (kHz = 1000 hearts).

An auditory impression occurs when humans perceive sound waves in a frequency range from around 16 Hertz to around 20,000 Hertz. Sound whose frequencies are lower is called infrasound, the frequencies above are called hyper- or ultrasound. Animals hear in other frequency ranges.