Hearing Test

What Does a Hearing Test Involve

In order for one to understand what a full diagnostic hearing test actually involves, it is imperative to understand how we actually hear.

When sound is heard by the ear, sound waves are initially collected by the outer ear and directed along the ear canal to the eardrum or tympanic membrane. As these sound waves hit the eardrum, their impact creates vibration of this membrane, which in turn then causes the vibratory motion of the three little bones, the ossicles, in the middle ear cavity. The smallest of these ossicles, the stirrup, fits into the oval window between the middle and inner ear.

When the oval window vibrates, fluid within the inner ear transmits these vibrations into the cochlea, which is a delicate, snail-shaped structure within the inner ear cavity. The cochlea consists of thousands of microscopic hair cells which are bent by the wave-like action of the fluid within it. The bending of these hairs sets off nerve impulses which are then passed though the auditory nerve to the hearing center in the brain. This center then translates these nerve impulses into sounds which the brain recognises and decodes into meaning.

Understanding how we hear will make the understanding of what a hearing test involves much clearer and more sensible.

An initial consultation with an Audiologist in order to determine whether one has a hearing loss would entail:

• Case History: This entails establishing a rapport with a patient, as well as trying to determine the patient�s main complaint.

• Otoscopic Examination: This entails the Audiologist doing an examination of the patient�s ear canal in order to rule out any obstruction of the outer ear canal with debris such as ear wax/cerumen, foreign particles such as insects, or abnormal growths within the canal, such as congenital malformations and bony growths of the ear canal. In the event that any obstruction is found, the Audiologist would not be able to continue testing the patient prior to an ENT referral for further management of the obstruction.

• Tympanometry: This involves the measurement of the ear canal volumes, the pressure within the middle ear cavities, and the presence or absence of acoustic reflexes, either ipsilaterally or contralaterally, or both. These measurements would provide information regarding the functioning of both the tympanic membrane/eardrum and the middle ear cavity.
  
  Often times, this test would also determine whether an ENT referral is necessary, or if further testing can be continued.
  
  
• Pure Tone Audiometry: This involves the establishment of ones true hearing thresholds via both air conduction and bone conduction testing in a sound proof booth. Air conduction testing is the establishment of ones thresholds via presenting pure tones through earphones to the ear. The tones pass from the outer ear, through the middle ear to the cochlea in the inner ear and finally to the brain. Bone conduction testing involves presenting the tones via a bone conductor directly to the mastoid bone, under which runs the auditory nerve, which directly transfers the tones to the brain.
  
  
• Speech Audiometry: This involves assessing ones speech reception thresholds as well as determining ones ability to discriminate speech in noise.



• Specialised tests (only if necessary and indicated)



• Diagnosis and Interpretation of the results



• Referral and /or Treatment

What do the Results Tell Me

Hearing Loss on the Audiogram

• Type.
  Related to anatomy and site of lesion.
• Degree.
  Amount of hearing loss.
• Configuration.
  Which pitches are affected?
• Laterality.
• Symmetry.

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WHAT SHOULD I EXPECT FROM A HEARING EVALUATION?

Q: I'm having my hearing tested. What should I do beforehand?

A: It is a good idea to make sure that your ear canals are clean before a hearing test. Earwax can affect the results and make them unreliable. It is preferable to have the earwax removed by a specialist. Confirm your appointment and bring any prior hearing tests with so that a prognosis can be formed from all the available information. Ensure that you understand the billing structure of the practice you are visiting and bring all medical aid information and additional payments with.

Q: What will happen at my first appointment?

A: Your audiologist will do a thorough hearing test consisting of an otoscopic examination, tympanometry, pure tone audiometry and speech audiometry. They will perform further specialised tests should it be indicated e.g. for middle ear pathology or cochlear pathology. You will be referred to an Ear- Nose and Throat specialist if there is something that can be done clinically in order to improve your hearing. A hearing loss that is found to be purely a nerve loss (in the cochlea) will then be considered for a hearing aid fitting.

Q: Will I get my hearing aid immediately?

A: No! You will first have to decide what type of hearing aid is suitable for your hearing loss. Various factors need to be considered, e.g. How much you are able to pay for the hearing aid and how much the medical aid will pay for the hearing aid; What sort of technology is needed for your lifestyle; Is a binaural fitting essential or can it be spaced over a couple of years. Once a decision has been made about the type of fitting, a motivational letter and full audiogram data will have to be sent to the medical aid for approval before payment is guaranteed.

Some audiologists take an impression of your ear canal immediately in order to make the hearing aid or mould. This is only a bad idea if you are going to wait a number of months before making the hearing aid because the impression can shrink or warp resulting in fitting problems. It does, however, stop you having to make an extra visit to your audiologist just for this!

Q: What is the next step?

A: Once the hearing aid has been ordered, made, and delivered, a hearing aid fitting will be organised. During this appointment the hearing aid will be adjusted to suit your hearing loss. Your audiologist will also discuss the handling and cleaning of your hearing aid. This is usually rather a lot of information to gather in a short session so make sure that you understand the basics before you leave. A hearing aid that is not being worn is of no use to anybody!

Q: How do I listen with my new hearing aid?

A: You will initially find that sounds are very different than you remember them and probably a lot louder! If you find that you are becoming irritated with the hearing aid, take it out but try to keep it in the following day for an hour longer. In this way you can gradually get used to the sound. Try to keep a diary of sounds that are good and those that are bad. If we find that something has been bothering you for 2 weeks it means that it should be adjusted to suit you.

Q: When do I go back to my audiologist?

A: It is important to keep going back to your audiologist to get the fine tuning of the hearing aid right. Some people know within a couple of days which adjustments should be made and some take longer to first experience the hearing aid in different situations. It is, however, important that you do go back until you are satisfied with the hearing aid. If you aren't happy with it you won't wear it and that makes for rather a waste of time and money.