CHAPTER 9

TYMPANOGRAMS AND AUDIOGRAMS

A tympanogram is a graph produced by putting a sound wave against the ear drum. The tympanogram indicates Eustachian tube [ET] and middle ear [ME] function. It is an objective test in contrast to looking at ear drums which is subjective.

Tympanograms do not measure hearing. However if the tympanogram is abnormal, depending on the type and severity of the abnormality, we can infer that there may be some problems with hearing. Children are individuals and there is significant variation in the hearing of infants and children with middle ear problems. Hearing testing in infants may have some difficulties, as will be discussed in detail later in this chapter.

Tymps can be printed out and kept with the child’s medical history. Serial tymps are helpful to look at the progress of the child’s ME problems. It would be helpful if tympanometers were readily available.

Some GPs have a tymp available. Audiology laboratories will do a tymp 


SUMMARY

TYMPANOGRAMS

A tympanogram is a graph that indicates the amount of vibration of the ear drum and the pressure at which the ear system is functioning.

The ME pressure indicates how well the ET is functioning. The compliance indicates how well the drum is vibrating and this may indicate whether there is fluid in the ME cavity. It is important to look at the shape of the graph as occasionally the figures may be misleading.

A tympanogram is a simple, non-invasive test and is not distressing for the child. Testing takes about 30 seconds for each ear. The child needs to be still and quiet for perfect testing conditions. Although testing requires a little ‘co- operation’ from the child it does not require a response from the child.

Tymps are an extremely useful and objective way of assessing ME and ET function. It is not a hearing test, but if abnormal, depending on the type and severity of the abnormality, some degree of conductive [middle ear] hearing problem may be assumed.

Ideally, tymps should be easily available. I believe that every child health nurse, school health nurse, primary care department and GP should have access to a tympanometer and be able to interpret the graph.

Although looking at the appearance of the ear drum is a subjective assessment, it should be used in conjunction with the tymps to make a decision about the child’s ear health.

Understanding how to interpret a tymp is discussed in detail in this chapter. Parents are encouraged to obtain a copy of the results of the child’s tymp, including the actual graph, not just the figures related to it. The graph can then be compared with graphs shown, to interpret the meaning of the tymp and to follow the child’s progress.

Tymps do not always exactly fit into classic type A, B or C graphs and interpreting these tymps usually depends on looking at a series of tymps and knowing whether the tymp is improving or deteriorating.


AUDIOGRAMS

An audiogram is a graph resulting from testing hearing.

All newborn infants should have a hearing screening test soon after birth to detect sensori neural hearing loss or sensorineural hearing impairment. SNHL [or SNHI] is usually due to abnormalities of development of the cochlear but can also involve the auditory nerve or hearing related areas of the brain. The earlier hearing loss is detected and management strategies begun, the better the outcome for language development. If major SNHL is not detected until after the child is six months old there is a high risk that the child will not develop normal speech.

A normal newborn screening result does not mean that the child cannot develop sensori neural hearing loss later.

Most children’s hearing loss is conductive loss, related to ME problems of effusion and/or infection.

Standard hearing testing of infants and young children requires responses from the child when they hear a sound. Whether a young child responds depends on many factors apart from the child’s hearing and there may be doubt about the reliability of the results. Older children who can co-operate and use ear phones produce more reliable results. Conductive hearing loss tends to fluctuate so testing may not give a true indication of the implications for learning because it may be different on different days.

Older children can be tested for air conduction [i.e., standard testing], bone conduction and speech discrimination— including speech discrimination in background noise. These tests provide more information about the type of hearing loss and its impact on the child’s ability to hear in a more ‘normal’ environment that the ‘abnormal’ environment of a sound proof booth. It also reduces the difficulty of assessing the quality of the sound heard, to decide whether the child is hearing sounds as muffled or distorted.

More sophisticated testing may be needed if there is still concern. This may be done by audiologists, ENT specialists or at a specialised testing centre [e.g., at a children’s hospital]. This may be needed for infants with suspicion about their hearing and for older children with unusual hearing loss.

When an abnormal test result is obtained with standard testing, it is important to clarify the problem quickly rather than waiting for several months, in the hope that the infant will be more co-operative with testing at a later session.

Although most people accept that children with MEE may have low frequency loss and fluctuating loss, many people seem less aware that some children with ETD [negative pressure] can also have significant hearing loss.

The level of hearing accepted as normal for children is usually 15 or 20db, but should possibly be 10–15db. Hearing at levels of 20db [or greater] may create difficulties with language development in infants and for learning for older children in the noisy school environment. Unlike adults, children do not have enough experience of language to fill in gaps when listening in the less than perfect hearing environment that is the real world….



Back to Top