Well babies
OAE testing is commonly used as the primary hearing screen in newborns with no known hearing loss risk factors. Failure to show a strong OAE indicates that further testing or observation is necessary. Most babies who fail a first OAE test pass a second test when the middle ear and ear canal have become clear.

At risk babies
OAE testing is frequently used as the initial screen within the ‘at risk’ population. Passing the OAE test indicates that normal middle ear and cochlear function is present. The specific risks must be evaluated to determine whether ABR testing is necessary, even after Pass at OAE. Certain conditions indicate the possibility of retro cochlear/neurological disorders, which the OAE test cannot detect.

Infants
Observe the ear canal and select an appropriately sized probe tip. Place the probe firmly in the ear canal. It is acceptable to hold the probe gently in the ear if necessary. Place the cable so the child cannot reach it. Have the child entertained and distracted during the testing. Occasional speech and vocalisation will not prevent successful testing. See above for the level of background noise, which can be tolerated.

Children older than one year have more mature ear canals that exclude more external noise than that of the newborn. Slightly more external noise can therefore be tolerated.

Adults
The ECHOCHECK may be used for testing children and adults’ ears. The ECHOCHECK is extremely sensitive to any factors that depress cochlear or middle ear function. Very slight pre-clinical conditions may results in failure on the ECHOCHECK.

The ECHOCHECK OAE screener provides a test of cochlear function, which parallels and complements the generally used ABR screening procedure. As with a screening ABR, a click stimulus is used in the ECHOCHECK. Responses obtained after averaging are validated as being characteristic of cochlear otoacoustic emissions. The analysis takes place over the primary speech frequencies between 1.5 and 3.0 kHz. The range is most effective for speech communication. The ECHOCHECK is programmed to pass an ear that has clear otoacoustic activity with in this frequency range. A signal-to-noise of 6db is required for a full pass and 3db signal-to-noise result in a provisional indication.

The ECHOCHECK is most suitable for well baby hearing screening, where a result should be obtained in ten seconds to one minute. The environmental noise affects the time taken to complete the test.

The ECHOCHECK is also recommended for use with babies with known risks of hearing impairment (e.g. babies who have undergone intensive neonatal care), in conjunction with ABR screening, especially where there is a risk of retro cochlear or central deafness being present. The two tests are complimentary. The presence of clear otoacoustic emissions in ears suspected of having hearing impairment by means of ABR indicates that careful assessment of the hearing aid requirements should be carried out.

An OAE is expected in a healthy young ear.

Newborn ears show very strong OAEs and the ECHOCHECK should stop in a few seconds if the ear is clean and free of moisture.

Babies older than one month can occasionally be too noisy and increase the testing time.

Some middle aged and older patients may not show clear OAE on the ECHOCHECK, even though their hearing is within normal limits. This is because the size of the OAE progressively reduces with age in some people.

It is possible for the ECHOCHECK to show a strong OAE in the presence of high frequency sensory hearing loss outside the main speech band range, although usually the OAE will not be strong in these ears.

The ECHOCHECK will show a strong OAE if middle ear and cochlear function are normal, irrespective of any retro-cochlear disorders.

Failure to show an OAE can be due to minor middle ear problems and therefore may not indicate sensory hearing loss. Failure to pass the ECHOCHECK test indicates that further audiological examination is necessary to investigate the possibility of hearing loss.

The controls and indicators of the ECHOCHECK are covered with a wipe-clean plastic surface.

Top left panel: Sound monitor
Noise OK indicator – illuminates green when noise is low enough to collect OAE data
Stimulus OK indicator – illuminates green when stimulus conditions are right to allow OAE testing.

Centre left panel: Ear Canal and status monitor
Before and after running the test this indicates ear canal volume/fit. The scale will be illuminated at one place indicating the relative size of the ear canal from large to small

During testing, the Status monitor scrolls from right to left to show that the test is progressing and indicates if data is valid.

Top right panel: OAE Result
Positive OAE indicator – illuminates green when a definite OAE is detected (>;6db SNR).

Marginal OAE indicator – illuminates yellow when a marginal OAE is detected (>;3db SNR, or >;6db SNR but too few valid sweeps collected).

Test Invalid indicator – illuminates orange when a probe movement occurs that could result in a potentially damaging level of sound, or if the level of noise collected could mask an OAE.

If no indicators within the OAE Result panel are illuminated at the end of the test no valid OAE has been detected.

Bottom panel: Operation
'On’ button and indicator.

‘Start/Stop/Save Left’ test button and indicator. During testing, this indicator is steady illuminated while data is being accepted. Whenever either the Noise OK or Stimulus OK indicators are extinguished, this indicator flashes to indicate that data is being rejected. Press this button to save result of left ear test.

‘Memory/save right’ test result button and indicator. Before running a test and after saving a test result, it is possible to review the last ten results by repeatedly pressing this button: the Status monitor indicates which result is being reviewed on the OAE Result panel. Press this button to save result of right ear test.

Self-diagnostics
All indicators on all the panels will flash during self-test and probe test sequences when the unit is switched on.