The Human Ear
A Blog By Karl Hall
As a Human we interpret the reality in front of us through our various senses. The biological mechanisms of the Human ear work together to create our sense of hearing, this give us the ability to interpret sound.
Our hearing is our most primary defence mechanism, as a developing fetus in the womb of our mothers the bones that make up our ears are formed at around 16 weeks. This means that sound and vibration give us our first perceptions of the world around us. Everybody in some form is an expert listener as sound gives us the ability to not only tell if somebody is lying or not through the timbre and tonality of the inflection of a word but also to perceive a threat even if our backs are turned.
This survival mechanism is reinforced even more by the fact that in order for sound waves to get from our ear into our audio cortex, where the sound is actually processed. It must first pass through the part of our brain which deals with our long term memory (Hippocampus) this allows us to instinctively associate sound with memories.
As well as it being a survival technique to perceive danger throughout our progression as a species it also gives us senses of nostalgia when we hear songs or sounds that we can not only relate to a memory but also emotions which are usually indicative to us at the initial time of hearing.
Although Sound is indeed a culturally and specifically perceived phenomena (I.e the difference in semi and microtonal music between east and west cultures our the preference between consonance and dissonance on a more personal level) we would all interpret a threat on a psychoacoustic level based on the proximity, amplitude and frequency of what we hear as the out ears are capable of perceiving these elements to give us a real time 3d perception of our sonic environment and in order for us to decode this complex information we have inherent in us a complex decoding device in the human ear. The reason we have to ears either side of our head is so that we can efficiently perceive sounds from 360 degrees around us.
Within a few milliseconds from their generation, sounds are processed by the outer, middle, and inner ears, where sound waves create vibrations along the basilar membrane of the cochlea, and converted to nerve impulses by the hair cells in the cochlea.
The ear flap (Pinna) is made mostly of cartilage, the shape of our ears are designed as essentially a device to channel sound into our ear canal. Because of the design of our ears and shape of our head we tend to hear what is in front of us better than what is behind us, this is called casting a sound shadow, also people with larger ears tend to have better hearing at the size of the pinna dictates the amount of sound that can be channeled into the auditory canal by means of inverse square law.
The ear canal channels the waves to your eardrum, a thin, sensitive membrane stretched tightly over the entrance to your middle ear. Our ear canal is around 4cm long sand has oily sebaceous glands which act as protective barrier to the hairs in our ear and also create a disinfectant.
When sound enters the through the ear canal it causes the eardrum to vibrate. It passes these vibrations on to the hammer, one of three tiny bones in your ear. The vibrating hammer which is the outermost of these small bones in the middle ear causes the anvil, the small bone touching the hammer, to vibrate.
The anvil passes these vibrations to the stirrup, another small bone in which touches the anvil. From the stirrup, the vibrations pass into the inner. The nerve impulses reach the auditory processing areas in the central nervous system, which recognise the sound and integrates this knowledge with information from other sensory modalities. (e.g vision)
Tihe stirrup then touches a liquid filled sack and the vibrations travel into the cochlea, which is shaped like a shell. Inside the cochlea, there are hundreds of special cells attached to nerve fibers, which can transmit information to the brain.
It is widely believed that the cochlea functions to separate incoming acoustic frequencies by responding to different frequencies in different spatial locations along its length, it can be said that each region on the basilar membrane acts as a filter bank.
It is also worth noting that The cochlea within our ear has a conch shaped appearance. This design is in keeping with what is known as Golden Ratio which is a design which is inherent in almost every aspect of natures designs
Note the similarities in design. The Golden ratio not only has reoccurring properties within all elements of design but also applies a sort of algorithmic overlay onto how aesthetic beauty is interpreted by us as humans.
To finish off my blog I would conjecture that, like Darwin did with his analysis of the human eye, I would go as far as to say that the design and function of the human ear go beyond a mere trait of evolutionism. Although no doubts the manifestations and functionality arise from a biological means of progression (In the same way golden mean builds on previous complexity).
It appears apparent to me that in some respect we have been intelligently designed. This isn't a dogmatic elusion by any means but it merely comes with the understanding and appreciation for all forms of analysing the world around us, much like the way our primary sense gives us our first insight.
As our ears are sensitive instruments they are also susceptible to damage in a variety of ways. The type of damage incurred is categorized by which part of the auditory canal is affected. The three basic types of hearing loss are conductive, sensorineural and mixed hearing loss.
Conductive hearing loss occurs when there is an inefficiency in the conduction of sounds through the outer ear canal, eardrum and the tiny bones of the middle ear (ossicles).
Conductive hearing loss involves a reduction in sound level which is discernible by the loss of the ability to hear faint sounds.
Some of the causes of conductive hearing loss include; Fluid in the middle ear, impacted ear wax, infection and benign tumours.
Sensorineural hearing loss occurs when there is damage to the inner ear (cochlea) or to the nerve pathways between the inner ear and brain. This type of damage is in most cases cases irreversible and is the most common form of hearing loss.
Causes of this type of hearing loss include; Illness, drugs which are toxic to hearing loss, head trauma, ageing and exposure to loud noise.
When problems to hearing arise between Sensorineural and Conductive factors it is known as Mixed Hearing loss.
Conductive hearing loss occurs when there is an inefficiency in the conduction of sounds through the outer ear canal, eardrum and the tiny bones of the middle ear (ossicles).
Conductive hearing loss involves a reduction in sound level which is discernible by the loss of the ability to hear faint sounds.
Some of the causes of conductive hearing loss include; Fluid in the middle ear, impacted ear wax, infection and benign tumours.
Sensorineural hearing loss occurs when there is damage to the inner ear (cochlea) or to the nerve pathways between the inner ear and brain. This type of damage is in most cases cases irreversible and is the most common form of hearing loss.
Causes of this type of hearing loss include; Illness, drugs which are toxic to hearing loss, head trauma, ageing and exposure to loud noise.
When problems to hearing arise between Sensorineural and Conductive factors it is known as Mixed Hearing loss.
