How we hear
Sound is the vibration of air. The vibrating air enters the ear, and travels down the external ear canal. Then it reaches the eardrum (otherwise known as the tympanic membrane). The eardrum starts to vibrate. The 3 little bones of the middle ear are attached to the eardrum, and they start to vibrate. The third little bone is connected to yet another membrane which starts to vibrate. The membrane’s vibration causes the jelly of the inner ear to vibrate. All this time, the sound has been mechanical. Now, in the inner ear, there are specialised cells called hair cells which pick up the vibrations and then this mechanical energy is converted to electrical energy which is then transmitted by the nerve to the brain.
Infections can occur on the earlobe, in the external ear canal, in the middle ear, and in the inner ear.
External ear infections
The earlobe and/or external ear canal can become infected by a variety of bacteria and viruses, and can also be affected by skin conditions such as excema. We see many external ear infections caused by the use of dirty cellphones (and let’s face it, all cell phones are dirty!), excessive water in the ears e.g. from swimming; and from damage caused by the use of earbuds. We have little hairs in our ears that constantly sweep out dirt. We have natural ear wax that traps dirt and the hairs sweep out the wax.. When we use earbuds, we damage the little hairs and often push the wax back into the ear canal when it is, in fact, making its way out! Sometimes the external ear swells so much that the vibrating air (sound) is not able to enter the ear and a hearing loss results. When the ear is healthy, hearing is normalised.
Infections of the middle ear
The end of the external ear is sealed off by the eardrum, which is a window into the middle ear. The middle ear is a hollow space that lies in the bones of the skull. The middle ear area is lined by the same kind of mucous membrane that lines nose and mouth. There is a little tube that runs from the middle ear into the back of the throat right up near the back of the nose. This is the Eustachian tube. Most of the time, the Eustachian tube is collapsed. When we swallow, the Eustachian tube opens and allows fresh air to enter the middle ear. The fresh air equalises the air pressure in the middle ear.
The first of the 3 little bones of the ear is connected to the eardrum, and the other bones are carefully suspended. These little bones (the ossicles) transmit the vibrations to the inner ear.
The middle ear has an important extension – the mastoid bone, which looks a bit like Aero chocolate – lots of little air spaces.
An infection of the middle ear is known as “Otitis Media”. It is usually caused by a poorly functioning Eustachian tube. When the tube is blocked (such as when the mucous lining of the throat is inflamed because of allergies or a cold), then fresh air cannot enter the middle ear and the air pressure is not equalised. The ear can then fill with fluid, and this is known as "otitis media with effusion" or "glue ear". We also call this “serous otitis media”. The fluid is not infected and can sit in the middle ear for up to three weeks. It usually gets better without any intervention.
If the fluid lies in the middle ear for a while and becomes infected, we refer to the condition as “acute otitis media”. Pus and mucous build up in the middle ear and cause pain and swelling. The pressure in the ear can casue the eardrum to burst, and the pus and mucous discharge from the ear. This is a serious condition that requires medical attention.
When ear infections keep returning, or when the ear infections do not clear up over time, we call the condition "chronic middle ear infection". If the ear discharges, we call the condition "chronic suppurative otitis media". Chronic ear infections need to be treated because they can lead to permanent damage and hearing loss.
Ear infections can be treated by a GP or ENT.
Often antibiotics are prescribed but more often than not, the infections are viral.
If the Eustachian tubes do not function well, and fluid in the ear does not drain spontaneously, the ENT may advise the insertion of grommets. A grommet is an air tube or ventilation tube that allows fluid to drain out, and very importantly, allows fresh air into the ear. In time, most grommets fall out by themselves. Sometimes they need to be inserted repeatedly to maintain the health of the ear until the underlying cause of the ear problem resolves. (The picture on the right is an eardrum with a white grommet inserted).
Hearing loss and ear infections
Anything that impedes the transmission of the vibrations through the ear can lead to a hearing loss. When the middle ear fills with fluid, the hearing is partially lost. It is like hearing while wearing earplugs. The hearing loss mainly affects low frequencies, but enough to interfere with hearing speech, especially in noisy environments like work environments, shopping malls, and classrooms. Speech can sound muffled.
Thicker fluid in the middle ear can cause a moderate hearing loss, and it could become really difficult for the person the hear speech.
Is is recommended that children with ear infections that last longer than 3 months undergo hearing testing, and if necessary, the ENT or audiologist will recommend on-going hearing testing. Hearing testing is important for two reasons:
1. We can monitor the course of the disease through audiological testing
2. We monitor hearing and intervene when appropriate to ensure that the person hears as much as possible, and that speech-language development is monitored.
Do mild hearing losses affect speech-language development?
There is no doubt that a persistent hearing loss due to ear disease causes speech and language delays. The American Academy of Audiology stated, "We are convinced, from careful analysis of the voluminous research available, that a causal relationship does exist between communication disorders and early, recurrent, episodes of otitis media in infants and young children." In their guidelines, the Academy states that it is not only the severity of the hearing loss that plays a part, but the nature of the hearing loss. For example, the hearing loss fluctuates - it is worse at times and better at times; it does not always affect both ears the same; and it affects lower frequencies more than higher frequencies.
Of course, not every child who has ear infections will have difficulties with speech-language development, but because we are convinced that many children experience significant problems is association with ear infections, we err on the side of caution.
If a child has a hearing loss as a result of long-term ear infections, then we recommend that the child is tested by a speech therapist, and if necessary, enrolled in a period of speech-language therapy. Early intervention is known to result in better outcomes.
Finding the root of the problem
Sometimes, we focus on treating the ear infections, but don't look for the underlying causes. Of course prevention is better than cure, and so we try to eliminate the root causes of ear infections. Every person reacts differently to the environment, but we need to do some evaluation of factors such as :
exposure to pollutants
exposure to smoking
structural problems e.g. cleft palate
bottle drinking by babies lying down
developmental anatomy. Children's Eustachian tubes are shorter and so pathogens can travel to the ear relatively easily
Avoid using earbuds!! They damage the little hairs in the outer ear; they push the wax in; they can perforate the eardrum
Clean your cell phones and ear plugs regularly. Do not share ear plugs, earphones and headphones with others.
Ear infections and speech-language problems
AVOID USING EAR BUDS! They push the wax in further, and there is a chance that you could perforate your eardrum!