Fundamental Asynchronous Stimulus Timing Sound Coding Study (FAST)

The Fundamental Asynchronous Stimulus Timing (FAST) is a novel cochlear implant sound coding strategy. Potential benefits include improved battery life, in addition to improved localization for bilateral patients.

The Fundamental Asynchronous Stimulus Timing (FAST) strategy offers excellent potential as a low power alternative coding strategy to the current default strategy in Nucleus® cochlear implants, Advanced Combination Encoder (ACE). Additionally, FAST offers potential bilateral benefits - localization and listening in spatially separated noise - because it has been shown in acute, controlled studies to provide more access to interaural timing difference (ITD) cues (Smith, 2010).Previous research with experienced cochlear-implant recipients has shown issues with conversion from ACE to FAST. The FAST strategy typically sounds very different in quality, and acclimatization can be lengthy. This extended adaptation time makes it difficult to show conclusively that FAST is non-inferior to ACE for speech understanding. A potential barrier to evaluating performance with FAST in current cochlear-implant recipients is the extensive amount of prior experience that many recipients have using ACE. Hence, there is a distinct need to evaluate FAST in newly implanted recipients.

All patients will be receiving commercially available Cochlear™ Nucleus® CI24RE with Contour Advance™ Electrode or Cochlear™ Nucleus® CI512 cochlear implant with Contour Advance™ Electrode for this study. Group 1 will be receiving the FAST (experimental) sound coding strategy at initial activation and use it for the first three months.At the three month interval subjects in Group 1 will be switched to the commercially available ACE (control) sound coding strategy.

All patients will be receiving commercially available Cochlear™ Nucleus® CI24RE with Contour Advance™ Electrode or Cochlear™ Nucleus® CI512 cochlear implant with Contour Advance™ Electrode for this study. Group 2 will be the commercially available ACE (control) sound coding strategy at initial activation and use it for the first three months.At the three month interval subjects in Group 2 will be switched to the receiving intervention of the FAST (experimental) sound coding strategy. The experimental sound coding strategy will be used from 3-6 months post activation.

Commercially available Cochlear™ Nucleus® CI24RE with Contour Advance™ Electrode or Cochlear™ Nucleus® CI512 cochlear implant with FAST sound coding strategy using crossover design in newly implanted subjects. Both groups will receive the experimental and control strategy

Commercially available Cochlear™ Nucleus® CI24RE with Contour Advance™ Electrode or Cochlear™ Nucleus® CI512 cochlear implant with FAST sound coding strategy using crossover design in newly implanted subjects. Both groups will receive the experimental and control strategy

Open Set Monosyllabic Word Recognition is a test of 50 words each consisting of 3 individual speech sounds. The subject repeats the word s/he hears to the audiologist. The score is based on the percentage of words correct. The primary outcome measure to is determine if the investigational sound coding strategy (FAST) is non-inferior to commercially approved sound coding strategies (ACE) for word recognition in quiet with percentage of words correct.

The primary outcome measure to is determine if the investigational sound coding strategy (FAST) is non-inferior to commercially approved sound coding strategies (ACE) for BKB sentences in noise with mean signal-to-noise ratio (SRT) where participants could understand 50% of sentences in noise using ACE and FAST. Lower SRT values indicate better performance. SRT measures are obtained using two types of background noise. One is "Speech-Shaped Noise" which is white noise or tones made to mimic speech. The other is "Four-Talker Noise" which is multiple talkers made to mimic background conversation.

Inclusion Criteria Medical and audiological candidate for a unilateral CI24RE, CI512 or CI532 series implant Post-linguistically deafened Native speaker of American English Eighteen years of age or older Exclusion Criteria Previous or existing cochlear-implant recipient Pre-linguistically deafened (onset of hearing loss at less than two years of age) Ossification or any other cochlear anomaly that might prevent complete insertion of the electrode array Diagnosis of retro-cochlear pathology Diagnosis of auditory neuropathy Unrealistic expectations on the part of the subject regarding the possible benefits, risks, and limitations that are inherent to the surgical procedure and use of the prosthetic device Unwillingness or inability to comply with all investigational requirements Additional cognitive handicaps that would delay rate of improvement with the cochlear implant

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Smith, Z. M. (2010). Improved sensitivity to interaural time differences with the FAST coding strategy. Presented at the 11th International Conference on Cochlear Implants and Other Implantable Auditory Technologies, Stockholm, Sweden.