Objective Audition Measure in the Cochlear Implant User

Background: Nowadays there is no way to know objectively the resulting patient audition due to the incoming sound in the daily use of a Cochlear Implant. Audition provided to patient depends not just on the dynamic range wide, stimulus rate, pulse width, gap and level of the stimulation electric current but also on the sound input dynamic range wide, microphone sensibility and gain of the sound processor. On the other hand should be taken into account that responsiveness properties of the hearing tissue to electric current may vary along cochlea length. To achieve an auditory experience in the patient, time amplitude variations of output voltage of the band-pass filters are translated into an amplitude modulation to the stimulation electric current sent to intra-cochlear electrodes; so hearing tissue located in the neighborhood stimulation electrodes produces an intracochlear electric group response.

Objective: To obtain an electric measure related to the auditory experience of the implanted patient.

Methods: In sound field conditions and by using a set of tone pip´s which frequencies match the central frequency of active electrodes, scalp electric group response was registered while patient was asleep and using her/his CI. Population: 25 cochlear implant users, 3 to 5 y.o.

Results: There is a characteristic waveform and a sensibility measurement (μV/dB_HL) for individual electrode that are related to the loudness (response amplitude μV) and quality (response waveform) of the stimulation provided to the CI user.

Conclusions: Although it is necessary further researches this methodology may be an objective alternative to know about the CI user audition especially in non-cooperative patients.