Sense of hearing – the ear, sound and listening

The ears pick up one's own sounds and those made by others, human or animal. Unlike the eyes, the ears sit at the sides of the head. They are open to sounds from the entire surroundings; there is no need to turn towards a sound in order to hear it. The ears cannot be closed, so a person is connected with the sounds around them during all waking hours. Sounds cannot simply be ignored.

Hearing and listening

Listening, or conscious hearing, requires quiet. The listener has to keep still and take a back seat, as it were. Listening is a social activity focused on others, but it is also an inner activity. Generations of pupils have heard the teacher's request to sit still and listen carefully, and it contains exactly this: attention and stillness belong together.

Many animals can turn their ears towards a source of sound, as a horse or a cat does with its movable ear flaps. Humans have almost lost this ability to point the ears. In the phenomenological reading, animals hear well, but they do not listen in the human sense, because they cannot step back from themselves and become inwardly silent.

How the ear is built

The hearing organ can be divided into three parts. The outer ear, consisting of the auricle and the ear canal, captures sounds. The eardrum closes off the end of the ear canal.

The middle ear carries the sound further. It consists of the air-filled tympanic cavity, which holds the three ossicles, the hammer (malleus), anvil (incus) and stirrup (stapes), and of the Eustachian tube, which connects the cavity with the throat. The Eustachian tube opens briefly when swallowing, so that the air pressure on both sides of the eardrum stays equal. The ossicles pick up the vibrations of the eardrum and pass them on to the inner ear, concentrating them onto the much smaller oval window.

The inner ear lies deep in the temporal bone. It consists of a labyrinth, a system of fluid-filled cavities made up of the vestibule, the cochlea and three semicircular canals that serve the sense of balance. The cochlea is the actual hearing organ. It is a spiral tube in which vibrations of the fluid set a membrane in motion; fine hair cells on this membrane turn the movement into nerve signals. High tones are registered near the base of the spiral, low tones near its tip.

Three kinds of sound

Three types of sound can be distinguished. First there are everyday noises such as the rustling of leaves, the wind howling round the house, babbling water and all sorts of mechanical sounds such as cars and creaking doors. The second type is music, which is made up of tones and their relations. The third type is human speech.

Three aspects of every sound can be observed, whatever its type: its volume, its pitch and its tone colour, or timbre. The direction of a sound can be heard too, because it does not reach both ears at the same moment or with the same strength. The difference in time is at most a fraction of a millisecond, yet it is enough to tell where the sound came from. Accurately judging the distance and direction of a sound is a matter of experience. The shape of the auricle helps as well: its folds colour a sound slightly differently depending on whether it comes from in front, from behind or from above, and this is how a person can tell a sound behind the head from one in front, even though both reach the two ears at the same moment. People who lose hearing in one ear find it much harder to tell where a voice is coming from in a crowded room.

The range of hearing

Hearing declines with age, but it starts with a very wide range. Young people hear from about 20 to about 20,000 vibrations per second, a range of roughly ten octaves. For comparison, a piano covers a little over seven. With the years the upper limit falls, so that older people miss high tones first; speech with many hissing consonants then becomes harder to follow.

Other animals hear in ranges of their own. Dogs and cats hear tones well above the human limit, which is why a dog whistle can be silent to its owner, and bats and dolphins use very high tones for echolocation. Elephants, on the other hand, communicate with sounds so low that humans can scarcely hear them.

Sound reveals the inside

Looking at an object gives an idea of its exterior. Listening to an object gives an idea of what is within. It is often difficult, for example, to tell a glass pane from a plastic one by sight alone. Tapping the pane settles it at once. A cracked plate or bell can be heard, even when the damage cannot be seen.

Listening to people also reveals something of their inner life. Someone may look well turned out, but if they feel bad inside it is immediately apparent in the voice. Intonation betrays whether a person is sad, happy or excited, and on the telephone this is often all one has to go on.

The sound of an object is always the result of the whole, of substance and shape together. To ring, an object must be solid and free-standing. A copper bell hanging freely rings, but a bell standing on soft ground sounds like a lump of clay: it gives a dull thud. In the phenomenological approach sound is therefore considered an immaterial phenomenon. It is carried by matter, yet it is not a thing, and it disappears as soon as the vibration stops.

Hearing one's own voice

Everyone who hears a recording of their own voice for the first time is surprised: it sounds higher and thinner than expected. The reason is that the speaker hears the own voice in two ways at once. Part of the sound travels through the air to the ears, and part is carried directly through the bones of the skull to the inner ear. The bone-carried part adds depth that a listener in the room never hears. A recording gives only the airborne sound, as others hear it.

The ear also protects itself to a degree. With a very loud sound, two tiny muscles in the middle ear contract and dampen the movement of the ossicles, most of all for low tones. This reflex comes a fraction of a second too late for sudden bangs, and long exposure to loud noise can damage the hair cells in the cochlea, which do not grow back. The ringing in the ears after a loud concert is a sign of how hard the organ has been working.

Silence

Hearing also has its own relation to silence. Complete silence is rare; even in a quiet room the hum of the house, a clock or one's own breathing can be heard once attention turns to it. Silence is experienced not as the absence of hearing but as a space in which the smallest sound becomes noticeable. Music uses this constantly: a rest between two phrases is part of the melody, and a concert hall full of people can fall so silent before the first note that the silence itself seems to be heard.

Music and tone

People have a very fine perception of music and sound and can feel intimately connected with tones and melodies. High tones are generally perceived as clear, light, sharp and distinct, low tones as dark, full, warm, big and less distinct. A melody rising from low to high is often experienced as opening or lifting, a falling one as closing or coming to rest.

The sense of sight arranges colours in a circle; hearing has its own kind of return in the octave. A tone and the tone an octave higher are felt as the same note on another level, although the second vibrates twice as fast. Every musical tradition knows this, even when it divides the octave differently.

Seeing helps hearing

A final point of interest is the relationship between sight and hearing. Looking at something makes it easier to hear. This applies to speech: a whispered sentence is understood much better when the listener can see the speaker's mouth, as the blindfold exercise shows. It applies to music too. Someone listening to a symphony orchestra who keeps the eyes on the oboe hears that instrument more clearly than the others. Switching the gaze to the clarinet brings the clarinet forward, and so on.

Hearing among the senses

In the anthroposophical tradition hearing is the first of the four "higher" senses described by Rudolf Steiner, followed by the senses for word, for thought and for the other person's self. Seen that way, hearing stands at the threshold between the senses that perceive the physical world and the senses that perceive another human being. The pages on movement and smell describe other senses in the same series.

What is heard is never the object itself but its response to being touched, struck or blown. In a violin, the body of wood makes the vibrating string audible; without it the string alone would hardly be heard beyond the player.