The ear is made up of 3 parts:
The Outer Ear consists of the pinna, the ear canal and the eardrum. The eardrum or tympanic membrane is the boundary between the outer and middle ears.
The Middle Ear consists of an air-filled cavity containing a chain of three little bones: malleus, incus and stapes. They transmit sound vibrations from the eardrum to the inner ear. A small passage called the Eustachian tube connects the air-filled middle ear cavity with the back of the throat. The function of the Eustachian tube is to equalize the air pressure in the middle ear to that outside the ear.
The Inner Ear consists of the cochlea (shell-shaped bony spiral) filled with fluids and lined with tiny hair cells that connect to nerve endings. These nerve endings connect to the hearing (auditory) nerve that transmits sound messages to the brain. The organ of balance is also connected to the inner ear.
The central auditory system is a network of neural pathways in the brain that is responsible for sensation and interpretation of sound characteristics such as pitch and rhythm as well as sound localization, speech understanding in noisy listening situations and music perception.
Hearing between 250 Hz and 8 kHz in the range of -10dB to 20dB is considered to be normal.
Hearing thresholds (softest sound that can be heard by a particular person) poorer than 25dB is considered to be a hearing loss. Poorer hearing thresholds generally indicate a larger degree of hearing loss.
Types of Hearing Loss
There are a variety of causes that can lead to hearing loss. Depending on the part of the ear that is affected, we distinguish between three types of hearing loss:
1. Conductive hearing loss
2. Sensorineural hearing loss
3. Mixed hearing loss
Conductive Hearing Loss occurs when there is disruption of sound transmission in the outer or middle ear. It is frequently a temporary condition and can frequently be corrected or improved with medical or surgical treatment. People with conductive hearing loss notice a reduction in the volume of sound. Hearing aids may be considered if medical or surgical treatment is ineffective.
Sensorineural Hearing Loss occurs when the hair-cells lining the cochlea are damaged, resulting in a diminished sound signal being sent to the brain. As well as noticing a reduction in the volume of sound, people with sensorineural hearing loss may also have a distortion in sound clarity and abnormal perception of loudness. Sensorineural hearing loss is permanent and does not usually respond to medical or surgical treatment. The most likely causes of sensorineural loss are Noise Exposure and Ageing (Presbycusis). Hearing aids are an effective treatment option for sensorineural hearing loss.
Mixed Hearing Loss is a combination of Conductive and Sensorineural losses. Dependant on the pathology involved these losses can be treated via medical/surgical or audiological means.
Noise Exposure and Hearing Loss
Ageing and Hearing Loss
Prolonged exposure to loud noise can permanently damage hearing by causing the destruction of hair cells in the cochlea. In the past hearing health has been neglected in the work place and as a consequence hearing loss is prevalent amongst people who were exposed no noise professionally or recreationally. This includes tradesmen, musicians, engineers, dentists, policemen and armed forces etc.
Ears should be protected from loud noise whether it be industrial noise from machinery or loud recreational noise from music concerts, firearms, power tools or motors.
The popular notion that with age we become "hard of hearing" is often true. Hearing loss occurs gradually in most people as they age. This is known as presbycusis. We are born with a set of sensory cells, and at about age 18 we slowly start to lose them. High noise levels that we are exposed to, chemicals in the air, disease processes and genetics all contribute to the overall loss and impact over time. According to The LISTEN HEAR Report on the Economic Impact and Cost of Hearing Loss in Australia, 2006, about 1 out of every 3 Australian adults aged 70 and over has a hearing loss. As many as 1 in every 6 people in Australia suffer from hearing loss...
Meniere’s disease is a condition in which there is an excess of fluid in the inner ear. The excess fluid disturbs the ear’s balance and hearing mechanisms and produces a range of symptoms, which may include vertigo, tinnitus, fluctuating hearing loss and a feeling of pressure or fullness in the ear
Attacks of vertigo usually occur in clusters with varying periods of remission (from days to years) between attacks. Vertigo attacks can occur without any warning and you cannot predict how severe the vertigo will be or how long it will last. In the early stages of the condition, hearing returns to normal levels following an attack, but as the disease progresses measurable and permanent hearing loss occurs. An ENT consultation, an audiological assessment and possibly other balance tests may be required to diagnose this condition.
Dementia and Hearing Loss
Hearing loss, a troublesome fact of life for many people over 50, had recently been linked to an increased risk of acquired cognitive problems such as dementia. This connection had been shown in several recent well-regarded studies. It is believed that in many cases treating hearing loss earlier and more aggressively could help stave off cognitive decline and dementia. In a 2013 study, overall cognitive abilities (including concentration, memory and planning skills) of nearly 2,000 older adults with average age of 77 were tested. After six years, those who began the study with hearing loss severe enough to interfere with conversation were 24% more likely than those with normal hearing to have seen their cognitive abilities diminish. Essentially, the hearing loss speeds up age-related cognitive decline.
While tinnitus (noises in the ears or the head) is a fairly common problem, there are many effective methods to treat (or at least reduce the impact of) the sensation.The first step to effectively manage tinnitus is to find an underlying cause. You should have a medical examination with an ENT specialist and conduct a full hearing evaluation with an audiologist as a part of an investigative process.
Tinnitus can be associated with conditions that occur at all levels of the auditory system.