Study of Auditory Performance on Prosodic Tests in Cochlear Implanted Subjects Using a Fine Structure Strategy

Main objective:

Investigate how the FineHearing strategy of the MED-EL cochlear implant can extract prosody based solely on the frequency of the voice fundamental (F0) in speech

Secondary objectives:

Evaluate the time evolution of the results of prosodic tests Evaluate the time evolution of the results of differential frequency threshold test Evaluate the time evolution of vocal audiometric tests in silence and noise Evaluate the correlation between prosodic test results and frequency differential threshold results

Introduction:

Prosodie is the study of the phenomena of accentuation and intonation (variation of pitch, duration and intensity) allowing the conveyance of information related to the sense such as the relief, but also the assertion, interrogation, injunction, exclamation ...

It has a role at the grammatical, emotional and pragmatic levels of communication by informing about the emotional state of the speaker (sad / happy), about sex and identity, about the type of statement (question / affirmation) and about the borders in the sentences.

The auditory cues that play a role in the perception of prosody include changes in the fundamental frequency F0 (ie vibrational frequency of the speaker's vocal cords) during a speech, the duration of the syllables, or the rate or intensity of the speech. \[Di Christo 2013\] The cochlear implant is a device for auditory rehabilitation. Its principle is to transform the analog signals recorded by a microphone into digital signals that directly stimulate the fibers of the auditory nerve through electrodes inserted into the cochlea. \[HAS 2012, HAS 2007, http://www.has-sante.fr\] Cochlear implants are indicated in cases of severe or profound sensorineural deafness.

Conventional stimulation strategies in cochlear implants (e.g. ACE, CIS) use the place of the electrode to code the frequency by sending low frequency information on the apical electrodes and high frequency information on the basal electrodes. The stimulation rate of the electrodes is constant. \[Wilson \& Dorman 2008\] The pitch is only partially transmitted by these conventional strategies \[Moore 2003; Oxenham 2008\] which would explain the poor results of cochlear implants in the perception of music \[Bruns \& al. 2016; Galvin III \& al. 2009; Veekmans \& al. 2009; Cooper \& al. 2008\] and prosody \[Kalathottukaren \& al. 2015 ; Meister et al. 2011; Meister et al. 2009\].

In the FineHearing strategy of the MED-EL implant, the rate of stimulation on the low-frequency electrodes is related to the frequency of the sound and makes it possible to code the frequency information temporally.

\[Rader \& al. 2016\] have studied the contribution of adding to the tonotopic coding of the frequency (classical strategy) a temporal coding of the information by varying the stimulation rate. The results obtained show that providing this frequency information by time coding makes it possible to obtain perceived pitch much closer to the expected pitch (of normal-hearing) and less variability, especially at low frequencies. With fixed stimulation rate (classical strategy) low frequencies are poorly coded, whereas with the variable stimulation rate they are better coded.

The FineHearing coding strategy of MED-EL with long insertion of electrode could therefore make it possible to better transmit the prosody and specifically to better extract the fundamental frequency F0 of the voice.

Objective of the study The objective of the study is to evaluate if the FineHearing strategy of the MED-EL implant allows to better transmit the prosody and specifically by the fundamental frequency of the voice (F0).

Main objective:

Show that the MED-EL FineHearing strategy (with deep insertion of the electrode) allows to extract prosody cues based only on the fundamental frequency F0.

Secondary objectives:

* evaluate differential frequency thresholds and correlation with prosodic performance
* Evaluate the positioning of the electrode array and its effect on prosodic performance

Plan of study:

It is a prospective open multicenter longitudinal study: measures will be done on the patient at 6 and 12 month post-activation.

Eligibility Criteria:
Inclusion Criteria:

* Patient with MED-EL cochlear implant (Sonnet / Synchrony)
* Adult patient (≥ 18 years old) speaking French
* Patient having an estimate of the optimal size of the electrode for its cochlea with the MED-EL software before their implantation.
* Patient with post-implant audiometry thresholds without cochlear implant \> 80 dB HL on 250 Hz, 500 Hz and 1000 Hz frequencies (no residual hearing)
* Patient with vocal audiometry in quiet on Fournier's disyllabic words ≥ 70% at 6 months post-activation

Exclusion criteria:

* Retro-cochlear pathology: auditory neuropathy, vestibular schwannoma