The various hearing tests give a good overall picture and indication of the process of the loss of hearing. Therefore keep all audiograms for your personal file. A visit to the Audiological Centre is not only necessary for setting new hearing aids and cochlear implants, but also to have hearing aids paid by the health insurance.
The types of tests are generally the same for children as they are for adults. However, an adjusted, more playful way of testing is applied for a number of tests.
Presently, tests are also developed that can measure the effort made for hearing. These tests are not generally applied yet.
The neonatal hearing screening, also called algo screening or OAE screening, is a hearing test for new-born babies. All children born in the Netherlands are eligible to this test. This screening of hearing checks whether the hearing of a new-born child is sufficient for normal development of language and speech.
If this test shows that a child does not hear (well), more tests are done by an ENT specialist and researchers in an Audiological Centre. Usually a DNA test is offered as well in order to find out the hereditary factors that may explain the deafness.
Otoscopy is a thorough examination of the auditory duct and the eardrum. Using otoscopy the ENT specialist can easily find out whether there is an explanation for the hearing complaints. During the examination the physician looks with an ear speculum in the ear.
The OAE hearing test measures the activity of the hair cells in the cochlea. OAE stands for Oto-Acoustic Emissions. This is the phenomenon in which the ear itself produces a response to a short clicking sound. During the test, you will hear short sounds through special ear plugs. The response of the ear to this is measured using special equipment. Nothing is expected from you or your child, except sitting as calm and still as possible.
A test for hearing direction makes clear to what extent you can determine where a sound is coming from. This is only possible when both ears (with a hearing aid or cochlear implant) function almost equally well. During the test you will hear sounds through various loudspeakers that are placed around you. You have to indicate from which direction (so from which loudspeaker) the sound is coming.
The BERA (Brainstem Evoked Response Audiometry) hearing test provides information about the functioning of the cochlea and the auditory nerve. This test measures the transfer of the sound by the auditory nerve to the brains. The BERA hearing test can determine the hearing threshold for high tones. Also any disorders of the auditory nerve can be found.
When doing the test, three or four electrodes are stuck to the (fore)head and behind the ears. Then you will hear noise through a headphone. The electrodes determine the activity of the nerve in response to the noise.
The test will take about half an hour. During the test you have to lie as calm as possible. This is often difficult for (young) children. Therefore they are usually lightly anaesthetised for the test. Babies up to six months can often be tested while they are asleep.
The speech audiogram test is also known as the ‘words test’. When making a speech audiogram you will hear words of various loudness through a headphone. You have to repeat these words. The speech audiogram shows to what extent you can distinguish various sounds, for example the difference between ‘bake’ and ‘wake’. Actually, the speech audiogram tests the difference between hearing and understanding. Children younger than five years do not always have to repeat the words but they can point at the corresponding picture or object.
The result of a speech audiogram hearing test is recorded in a diagram. This diagram shows how much percent speech you can hear at different sound volumes.
The horizontal axis shows the sound volume: zero decibel (dB) means virtually no sound. The further to the right in the audiogram, the higher the number of dB, so the louder the sound.
The diagram shows the results of the measurements with the right ear, left ear and/or both ears together in separate lines. These results are compared with the standard curve (see the dotted line).
No matter the volume of the given sound, it may happen that a person can never understand 100% of the given words (see the third line starting at 60 dB). In this case this person can understand 70% at the most. The difference (100% – 70% = 30%) is called the discrimination loss.
The far right curve in the diagram shows that the understanding of speech decreases when the sound level increases. This results in a helmet-shaped curve. In this case one speaks of ‘phonemic regression’ or ‘roll-over’.
Many Ushers know this test by the name ‘beep test’. During this test you will hear various tones that are alternately loud, soft, high and low. You indicate whether you hear the sound every time. In this way it is determined how loud a certain sound must be for you to hear it. This is your hearing threshold.
When testing toddlers and infants, this is often done using blocks: every time the child hears a sound, it must put a block into the box (play audiometry).
By means of this test it can be investigated to what extent you can understand speech while there are other noises in the background. The test provides insight into the speech threshold: it shows how loud speech must be in relation to the noise in order to be able to properly understand it.
There are various testing methods. A well-known method is the Plomp test.
You hear sentences through a headphone or loudspeaker and at the same time there is a ‘speech noise’ (buzzing of a large number of people). You have to repeat the sentences. The loudness in which the sentences are given is always adjusted to what you can and cannot properly understand. In this way a signal-noise ratio is measured. This gives an indication of your speech threshold.
The question whether the Plomp test correctly reflects the problems experienced by people who are hard of hearing in practice is under discussion. In fact, there is a monotonous noise, which the brain can easily filter out. It would be better to do the test with an alternating noise: for example, noise from traffic, from a few speakers, from a large number of people talking, sometimes loud, sometimes soft in the background will give a much better indication of the understanding of speech in daily practice.
The tone audiogram indicates your hearing threshold: which sounds can you just hear? A loudness measurement provides insight into the build-up of loudness of your hearing above the hearing threshold: when do you experience a sound as being soft, normal, loud and very loud?
During the loudness test you are given a headphone through which you hear sounds of various loudness and pitch. After each sound you indicate how you have experienced this: not audible, very soft, soft, normal, loud or very loud. Your answers are entered into a computer. The curve in the resulting diagram indicates how you experience sound. The outcome may be that you are insensitive to soft sounds and/or over-sensitive to loud sounds. This information is important for selecting the proper hearing aid – and the correct setting of this.