The Disability Information and Resource Centre

You can close your eyes when you do not want to see. You can hold your breath when you do not want to smell. You cannot really shut down your ears when you do not want to hear. Your hearing, like your heartbeat, goes on working even when you’re asleep.

The ear is a very complex organ situated deep within the densest bone structure of the head. The three main parts are:

THE OUTER EAR

Consists of:

• The Ear Flap -the pinna
• The Ear Canal - external auditory canal
• The Ear drum - the tympannic membrane between the outer and the inner ear.

The Pinna, the part we can see, has the job of collecting sound waves and conducting them to the canal.

The External Auditory Canal leads from the Pinna to the Tympannic Membrane. It is about 2.5cm long and is a slightly S shaped canal. Special glands can pump wax into the canal to trap specks of dust or insects, and a few hairs are present.

THE MIDDLE EAR

Is a small air filled cavity containing the three smallest bones in the body:

• The hammer - the malleus
• The anvil - the incus
• The Stirrup - the stapes

The malleus is firmly attached to the ear drum and the stapes is connected to the oval window of the inner ear. The incus is the connector between the malleus and the stapes. Sound waves make the ear drum vibrate. The three bones of the middle ear by vibrating themselves. The Eustachian tube is an air passage from the back of the nose and throat to the middle ear, ensuring that air pressure is maintained.

THE INNER EAR

Sits in on a hard-bone cavity and is a series of fluid filled bony canals.

The oval window separates the middle ear from the inner ear. The oval window leads to the “shell shaped” cochlear containing fluid and thousands of tiny nerve endings - hair cells. These tiny nerve endings lead to the auditory nerve which carries the sound messages to the brain. Also in the inner ear are the semi-circular canals. Set at right angles to each other the fluid in these canals sends information to the brain to enable the body’s balance to be maintained.

From the inner ear the auditory nerve transmits information to the brain where the final auditory processing takes place. Hearing loss can result from obstruction, damage or disease to any of these parts.

Hearing loss resulting from dysfunction of the outer or middle ear is a
conductive hearing loss.

Conductive hearing loss can often be corrected or improved with medication or surgery. The use of a hearing aid, or amplification, may restore hearing ability.

Hearing loss resulting from dysfunction of the inner ear or central hearing pathway is a sensory neural hearing loss.

Sensori neural hearing loss can seldom be corrected or improved with medication or surgery. The use of a hearing aid frequently assists discriminatory function. It is also possible to have a hearing loss which results form a combination of both conductive and sensori-neural dysfunction. It is then called a mixed hearing loss.

A hearing loss, either conductive or sensori-neural may be;

• unilateral dysfunction of the hearing mechanism affecting only the right or left ear.
• bilateral dysfunction of the hearing mechanism affecting both left and right ears.

In receiving speech there are closely related activities which are not the same but often confused.

HEARING

is involuntary. If ears are in good working order there is no choice. You cannot stop hearing whether you want you want or not.

LISTENING

is voluntary, you do it by choice. It is an activity of the mind which required effort and attention. It is hard work. The more severe the hearing loss, the greater the effort and concentration required.

UNDERSTANDING

Depends on being able to interpret the message correctly

CAUSES OF HEARING LOSS

Both conductive and sensori-neural losses can due to a variety of causes.

• Congenital or hereditary
• Obstruction or blockages of the sound pathways
• Accidents or damage to any part of the hearing mechanism
• Ototsclerosis or Cochleasclerosis where spongy bony growth immobilises or causes malfunction of the middle ear bones or the cochlea.
• Noise Indused Hearing Loss where ear damage occurs from prolonged exposure to excessive noise.
• Presbycusis - hearing impairment due to aging process.
• Meniere’s disease with symptoms of vertigo, tinnitus and hearing loss.
• Ototoxic drugs or allergies.

SOME ASPECTS OF HEARING IMPAIRMENT

The following symptoms may accompany a person’s hearing loss and/or ear condition.

The auditory (hearing pathway is one of the most delicate) and sensitive mechanisms of the human body. The complexity of an individual’s hearing ability and well being may be affected by the following factors -

1. TINNITUS (HEAD NOISES)

The incidence of Tinnitus is quite widespread and not always allied to a hearing loss. The noise may be mild or severe, continuous or spasmodic and likely to differ in sound for each individual. It is usually not possible to remove surgically or medically, but many strategies can be employed to help manage the symptoms. Some of these are:

• Consideration of food intake or nerve stimulants.
• Stress and tension management through relaxation.
• Reduction of excessive environmental noise and the use of quiet distracting sounds
• Avoiding fatigue and utilising exercise for physical well being.

2. RECRUITMENT

Although quiet sounds are not heard, loud sounds become abnormally loud sounds become abnormally loud. Sometimes, even light increases in the intensity of specific sounds can create a sensation of excessive loudness. This means that the threshold of hearing and threshold of pain are close and consequently the area of useable hearing is reduced. Hearing aid adjustments, through suppression, may help. Another reason why you should not shout at people with impaired hearing.

3. VERTIGO

The balance mechanism is part of the inner ear. Not surprisingly, therefore, a loss of balance may be associated with a loss of hearing. Dizziness and loss of balance can be very disrupting and embarrassing. However, there are coping strategies that can be learnt and helpful exercises to improve body balance can be recommended.

4. VARIABLE HEARING

It is a fact that with some type of deafness people can hear better sometimes than at others. Circumstances also affect how well one can hear. Some people hear better with a noisy background, other less well with background noise. Illness, fatigue and tension may also have a considerable impact on hearing ability. To say “You can hear when you want to” is just not true.

5. DISTORTED HEARING

Some frequencies may be heard normally and others not at all. Those with distorted hearing often say “I can hear your voice but I can not understand the words”. Increased loudness does not necessarily give increased clearness. Discrimination problems like this are best coped with by utilising speech reading and aural rehabilitation techniques.

DEGREE OF HEARING LOSS

Knowing your type of hearing loss is important in determining the type of treatment that you need (medical treatment, hearing aid etc) The are wide variations in communication abilities (clarify speech), depending on factors other than type of hearing loss. One of these factors is degree of hearing loss.

MILD LOSSES

You will probably experience no difficulty hearing in quiet one-to-one situations. In more difficult listening situations, such as groups, noise and at a distance, you may be under strain to hear. You may be asking “what?” quite often. You may or may not use a hearing aid, depending on the amount of strain you perceive and the difficulty of your work and social situations. People may be saying to you “You’re not paying attention” or “You hear when you want to hear” when in fact you have a real hearing problem.

MODERATE LOSSES

When a person is speaking at an average conversational level, it will sound very soft to you. Therefore, you will have more difficulty understanding speech sounds at distances greater than a few feet. High pitched speech sounds a “s,f,p,t,k” may or may not be heard. You will be unable to follow what is being said in large open areas (theatre, church, lectures, outdoors) unless you are very close to the speaker and can see his or her face. You must rely partially on visual clues (speech reading) to fill in what you miss. You should receive good help form a hearing aid.

MODERATELY SEVERE LOSSES

You will be unable to hear normal speaking voices and therefore, you will have to rely very heavily on visual clues (speech reading) in order to understand speech. You may hear some speech sounds if spoken loudly at a close distance. Understanding is greatly reduced unless you know the topic. You may need a hearing aid to hear voices at a normal speaking level. However, even with an aid, speech sounds may not all be clear without using visual clues.

SEVERE LOSSES

You will be unable to hear a normal speaking voice even at very close range. Speech sound will not sound clear, but you may understand vowel sounds if they are loud enough. You will have to depend mostly on visual clues (speech reading) to understand all speech. People may tell you that you speak too loudly. You will require the benefits of a hearing aid to hear voices or judge the pitch or loudness of your own voice and to prevent your speech deteriorating. However, not all speech sounds will be perfectly clear with amplification. You will have to rely on a hearing aid and speech reading to follow conversation.

PROFOUND LOSSES

You may not have an awareness of gross sounds in your environment. You will not hear normal speaking voices but hearing aids may be useful to provide auditory clues to aid speech reading. Your ability to understand speech, even with a hearing aid, will be dependent on your ability to speech read. Background sounds, if loud enough, may be distorted and difficult to discriminate. However, a hearing aid may give you a feeling of re-assurance since it supplies, through sound, contact with your everyday environment.

HIGH FREQUENCY HEARING LOSS

Many people have difficulty understanding what is being said, even though they can hear that a person is speaking. With this loss, a person has a reduced ability to hear the higher tones in speech and so has particular difficulty hearing consonant sounds.

• A person with a high frequency hearing loss might say:
• “I can hear people speaking but I can’t seem to understand what they are saying”
• “Everyone seems to mumble these days”.

The sounds “s’sh’f't’th’p'ch” may be difficult to hear or may be confused. For example FUN may be heard as SUN, or BACK may be heard a BAT. Of course the problem becomes worse if there is any background noise such as from the television, or from a group of people talking. The background noise interferes with the high frequency consonants as well.

WHAT CAN BE DONE?

Do not assume hearing aids restore normal hearing. People obtain assistance depending on their type and degree of deafness. Some receive benefit from amplification, other have trouble with discrimination and others only pick up enough background noise to stop them feeling entirely isolated from the environment.

In many cases a hearing aid may be fitted to boost the high sounds of speech to make the consonants clearer, and leave the low tones at a comfortable listening level. An audiologist will be able to advise whether this will be suitable for a particular individual.

In order to gain most benefit from a hearing aid, it is important to be aware of visual communication. this includes speech reading. Hearing tactics and listening skills can also assist.

* Source : Better Hearing Australia