Adaptation of hearing aids

The application of digital technology has facilitated the adaptation of hearing aids, through the application of PC software. The hearing care professional makes the relevant adjustments to the programming, molds, elbows and slim tubes.
Some management guidelines should be given, which, especially in the case of children, are based on the gradual increase in the number of hours of daily use of hearing aids. It is also part of the adaptation to offer basic knowledge to solve small problems that may arise during the first months of adaptation, such as changing the mold tubes, cleaning the filters, checking the condition of the batteries, replacement of the elbow etc.
Once the prosthesis has been adapted, its operation can be monitored and controlled by means of the hearing aid analyzer, which is a device that simulates the result of the hearing aid in the ear. The hearing aid to be analyzed is coupled to the artificial ear and an automatic recorder prints its response curves.
The postadaptation control includes the electroacoustic response of the prosthesis and the actual verification of the effectiveness of the adaptation, that is, the functional gain in the intelligibility of the language, by means of logoaudiometry. By comparing verbal audiometry in the open field before and after prosthetic adaptation, we can know the results in terms of intelligibility and discrimination, which is really the data of interest. The control of personal satisfaction after adaptation is also important.
Selection of the type of adaptation
The adaptation by airway is the first choice, the hearing aids are chosen depending on the age of the patient, their handling capacity, their preferences and the degree of hearing loss.
In terms of technology, the option is digital prosthesis. Sometimes patients acquire an analog hearing aid almost always for economic reasons or because they are users of analog hearing aids for a long time and do not adapt to the sound of the digital prosthesis. In children, the type of hearing aid that is prescribed is the behind-the-ear (BTE). The ear of the child is in continuous process of growth, the behind-the-ear hearing aids are those that adapt to the variation of the size of the ear since it is only necessary to change the mold and not the entire casing of the hearing aid. They are also the most resistant and easy to handle; likewise, they can cover a greater range of hearing losses.
In pure conduction hearing loss, the use of bone pathway hearing aids is indicated, as in the following cases:
- Imperforations or agenesis of the external auditory canal.
- External auditory canal stenosis.
- Tympanic perforations.
- Dry attic cholesteatomas.
Bench-case hearing aids can be prescribed in very isolated cases. As exceptional indications we can point out:
- Adaptation by bone pathway in the diadem (for example, in children with agenesis of the external auditory canal).
- People of advanced age with difficulties in handling the small controls of the usual hearing aids.
There is a special adaptation system called CROS (Contralateral Routing of Signal). Its main feature is a large distance between the microphone and the headset, since one and the other are on both sides of the head, which is convenient in two situations:

  • A very important hearing loss. In this case the microphone would be placed in the affected ear from where the signal is transmitted by wireless systems to the ear better in which an open mold is placed.

  • In cases of bilateral hypoacusis, with good thresholds in medium and severe frequencies, in these cases the adaptation with a closed mold is not effective because when hearing serious tones the patient refers a feeling of tamponed. Therefore the most convenient is an open mold.