[New potentialities of the hearing aids: the frequential transposition in high frequencies sensorineural hearing losses]

Hearing aids are becoming very complex instruments with amplification combining numerous signal processing. Digital equipment allows a transposition of acute frequencies towards lower frequencies. The goal of this study is to extend the possibilities of this transposition based on results obtained on 8 patients.

With these new systems, the frequential transposition involves tiny artifacts but the relation of frequency between the various components of the original signal is preserved. The transposition must be done only in the frequencies which are necessary and must as selective as possible. The structure of the original sound must be preserved which implies a certain flexibility and specificity to guarantee the individual needs of the patient. These complex adjustments are assisted by a linear transposition algorithm; Audibility Extender (Widex). This system was used to fit 8 patients presenting a significant acute frequency loss.

The improvement is evident on the level of perception of sounds of the environment and consonant recognition. The improvement is significant as well on the tonal sensitivity as on the threshold of vocal intelligibility with a conservation of the percentage of speech discrimination for monosyllabic words.

The frequential transposition is an alternative to cochlear implants in certain indications and has its place alongside hybrid implants. The indications are reserved to patients presenting dead cochlear zones in the acute frequencies. The algorithm with its various adjustments allows an adaptation preserving the characteristics of the transposed sounds. The adaptation to such a system of hearing amplification requires an adaptation, and rehabilitation is essential in all the cases.