Annex 12/6 - Technical devices
Annex for BIAP – Recommendation 12.6
Unilateral Hearing loss Assessment and Counselling after Newborn Hearing Screening (UNHS)
Children under the age of 1 year with a unilateral hearing loss
and the fitting of technical devices (e.g. hearing aids)
There is well proven data that in case a bi-aural fitting is indicated but one ear is neglected, the hearing process of the unattended side will be deprived. But until now there is no sufficient data that with UHL a very early hearing aid fitting (within the first 6 months of life) makes a difference on the future maturation of the auditory pathways.
Taking in account the cost of effort and stress for the family that is connected with any hearing-aid fitting in the first months of life and regarding the diagnostic uncertainties in a number of cases of mild to moderate hearing-losses the BIAP commission suggests as a compromise a start of a hearing aid fitting within the first 12 months of life (instead of a recommended start with in the first 6 months with bilateral losses).
In case of a hearing aid fitting the same principals should be respected as with bilateral fittings (see Recom. 06-11). For the evaluation of a hearing aid benefit audiometric test should include a proper masking of the normal hearing ear when tolerated by the child. Also the use of specially designed questionnaires can be recommended.
The hearing-aid fitting should be only finalized, if a sufficient acceptance of the hearing-aid by the child and the parents and a daily wearing of the hearing-aid is confirmed.
1. Unilateral moderate sensorineural hearing-loss or conductive hearing loss without atresia (hearing loss of 30-60dB) and normal hearing on the
- A hearing aid fitting on the hearing impaired ear may be beneficial and may lead/reinstate to a stereophonic as well as a directional hearing.
(In case of a unilateral hearing loss of less than 30 dB a benefit of a hearing aid can not be expected and even the loudness difference between the ears may be partly centrally compensated so that a directional hearing is still possible)
- In some cases a hearing aid fitting may still be successful with hearing losses between 60-80dB especially when a recruitment is present or regarding some cases of a high frequency hearing loss.
2. Unilateral deafness (hearing loss worse than 60dB, see exceptions above) and normal hearing on the opposite ear
- the patient will not benefit from a hearing aid fitting on the hearing impaired ear, because it will not be possible to provide enough amplification so that a level of equal loudness can be achieved on both sides.
- in school age a fitting of an FM-system might be useful to improve the signal to noise ratio in difficult listening situations (Recom 06-10 + annex FM)
- a C.R.O.S.-hearing-aid can be useful for some hearing situations, if the user is able to activate or deactivate the system according to his or her actual hearing situation. Especially in a diffuse noisy sound field the noise may be picked up by the C.R.O.S. microphone in a way that it can partially mask the speech information which the hearing impaired person tries to pick up with his/her good ear. Because a C.R.O.S. hearing aid cannot reinstate a true stereophonic hearing, using a C.R.O.S hearing-aid in a diffuse noisy sound field may prevent the benefit, the hearing impaired person might have without the hearing-aid by directing his/her good ear to the sound source. Therefore a tryout of a C.R.O.S. fitting should be restricted to older children (teenagers), who are able to cooperate and use the C.R.O.S technique selectively for special hearing situations (these considerations also apply for a transcranial C.R.O.S.-BAHA).
3. Unilateral conductive hearing-loss (e.g. major aplasia, severe ear canal atresia) and normal hearing on the opposite ear
- A bone conduction hearing aid with the microphone and the bone conductor both on the impaired side may be useful. The bone conductor + the hearing aid can be fixed with a metal bracket, a headband, a special cap or at the age of more than 5-6years a bone anchored hearing aid might be suitable. (If there exists still a small part of the external ear canal one should also try an air conduction hearing aid.)
- Concerning the age at the time of the fitting, one should consider the mechanical difficulties when fitting a bone conduction hearing aid to a very young child, therefore a start of the fitting within (before/at the end of) the first year of life should be feasible and sufficient.
Information about additional technical considerations in later years
FM-systems also without the use of a hearing aid may improve the signal to noise ratio in noisy hearing situations (i.e. school) (Recom. 06-10).
 A proposal for such questionnaires you can find on the webpage of the Klinik für Kommunikationsstörungen in Mainz, Germany: http://www.klinik.uni-mainz.de/kommunikationsstoerungen/mitarbeiter.html#c43553
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