Chapter 15: Cleft Palate and Audiology

Why Audiology?

Audiology is a routine part of the ongoing management of the child with a cleft palate because they may be more prone to middle ear problems than the normal population. Rarely do we see a permanent hearing loss, but a fluctuating middle ear problem, with its associated hearing loss, can affect the child's speech development, social interaction and progress at school.

How Do We Test Hearing?

1. For children under 6 months we use the technique known as Behavioural Observation Audiometry (BOA). In this procedure we present a range of noisemakers of known pitch (frequency) and loudness (decibels) behind the baby and then observe the baby's behaviour in reaction to the stimulus. Otoacoustic emissions (OAE) are also measured on the babies attending the clinic. Often called the cochlea echo, this measures the small sound created by the baby's ear in reaction to a louder stimulus transmitted through a tiny microphone placed in the ear canal. The result tells us if the tiny hair cells at the end of the hearing nerve are working properly. This test is rapid and painless.
2. For children under 3 years we use a technique known as Visual Reward Orientation Audiometry (VROA). In this procedure the child sits in a high chair or on mother's lap and is trained to look for a puppet show when he or she hears a warble tone coming from a loud speaker. The child usually finds this enjoyable and the test is over in half an hour. Headphones are not worn for this test (the children are too young to know they must not pull them off!) and the results tell us if your child has adequate hearing to develop speech properly.
3. For children over 3 years we use Pure Tone Play Audiometry (PTA). At this age your child is ready to wear headphones and we can test the hearing of both ears separately. For this procedure we train the children to throw a peg into a basket when they hear a sound. At this age we also test for bone conduction, by placing a small vibrator behind the child's ear and having him or her play the same game. The bone conductor tells us the state of the nerve of hearing, irrespective of any middle ear problem the child may have at the time.

15.1 The Audiogram

What Do The Results Mean?

The result of the hearing test (either PTA or VROA) is plotted on a graph called the audiogram. On the top of the graph is the pitch of sound, and down the side is decibels or loudness. The softest sound your child can hear is plotted against each frequency tested.

The pitch or frequency scale goes from a deep, low sound (250 hertz), such as a drum, to a high-pitched sound (4000 hertz), such as a telephone. Although the human ear can hear sounds far beyond this spectrum, we test only this limited range because it contains all the speech sounds. We need to ensure that the children are perceiving all the speech sounds adequately so that they will develop their own speech properly.

15.2 A normal audiogram

Figure 15.2 shows an example of a normal audiogram. The circles are for the right ear, the crosses are for the left ear, and the symbol is for bone conduction. Notice all levels are at or below 20dB (decibels).

Sometimes a child may develop a middle ear condition (see Section 14) which results in a conductive hearing loss. Figure 15.3 is an audiogram showing such a hearing loss. Note that the little symbols are within the normal range: this means the inner ear, the nerve, is working perfectly. However, when sound is heard via the normal route, through the middle ear, the hearing levels are not within the normal range. Now if we consider this child has a 40-50dB conductive hearing loss, and the average loudness of speech is 60- 70dB, then clearly the child is receiving the speech signal at a very reduced level.

15.3 An audiogram showing a conductive hearing loss

You may need to seek advice from the ENT surgeon, but before you see the surgeon we need to complete the audiology assessment with tympanometry, which is a direct measurement of middle ear function. In this procedure we insert a small probe into the ear (this is painless), which introduces a small amount of pressure into the ear canal. This pressure is varied from a positive to a negative point and a graph records the behaviour of the eardrum.

15.4 A child having tympanometry

Many parents want to know the meaning of the graph we get from this machine. Figures 15.5, 15.6 and 15.7 show normal and abnormal tympanograms. If your child's tympanogram is abnormal, you should seek advice from the ENT surgeon.

15.5 Normal tympanogram showing normal middle ear pressure and normal mobility of the eardrum.


15.6 Abnormal tympanogram showing very little movement of the eardrum, suggesting the presence of middle ear fluid.


15.7 Abnormal tympanogram showing significant negative middle ear pressure, suggesting Eustachian tube dysfunction and possible fluid

A permanent hearing loss is unusual for a cleft palate child, but it is not unknown. Sometimes the little nerve endings in the inner ear become damaged. This is the second type of hearing loss, known as sensori-neural hearing loss or nerve loss, and it may require the fitting of hearing aids. Your Audiologist will give you all the information you need about hearing aids and sensori-neural loss.

Further Information

To obtain further information on "Cleft Lip and Palate: A Parent's Guide", please contact Belinda Liston:

Belina Liston
Cleft Palate Clinic Coordinator
The Cleft Palate Clinic
The Children's Hospital at Westmead
Locked Bag 4001
WESTMEAD NSW 2145
AUSTRALIA
T: + 61 2 9845 2079
F: + 61 2 9845 2078
E: BelindaS4@chw.edu.au