Objectives: Bimodal Cochlear Implant Recipients simultaneously use a cochlear implant (CI) and a contralateral hearing aid (HA). In order to use interaural time differences for localization or to allow fusion of the electric and acoustic auditory percept, the latencies of auditory pathways of both devices must not differ too much. However, the body of evidence on how much commercial devices differ in latency and how much is tolerable is still emerging. Thus, this paper will 1) present new technical measurement results using the method proposed by Zirn et al. 2015 and 2) assess perceptual consequences of technical latency mismatch based on a review of literature on respective just noticeable differences.
Methods: The latency of the entire electric stimulation path for a Marvel CI (Advanced Bionics) was obtained by summing EABR wave V latencies evoked on different intracochlear sites as published by Zirn et al. 2015 and technical measurements of the group delay of the sound processor. The setup consisted of equipment which are available in most CI clinics: an oscilloscope, an acoustic sound source, a speech processor and a reference implant. In order to quantify the mismatch for bimodal CI recipients, the entire ABR wave V latency of the electric stimulation was compared with respective latencies for acoustic stimulation with hearing aids.
Results: : The ABR latencies of the Marvel CI are 16.0 ms, 14.3 ms, 13.0 ms, and 11.7 ms at 500 Hz, 1 kHz, 2 kHz and 4 kHz respectively. When compared to a typical FFT-based hearing aid, a latency mismatch between 0 and 2 ms depending on frequency can be observed. This latency mismatch is clearly below the just noticeable difference reported for bimodal CI recipients of 8 – 10 ms.
Conclusion: Reliable latency measurements can be conducted in CI clinics following the method proposed by Zirn et al. For the Marvel CI speech processor the latency mismatch is within tolerable limits for bimodal users of most modern hearing aids.

**Objectives**: Bimodal Cochlear Implant Recipients simultaneously use a cochlear implant (CI) and a contralateral hearing aid (HA). In order to use interaural time differences for localization or to allow fusion of the electric and acoustic auditory percept, the latencies of auditory pathways of both devices must not differ too much. However, the body of evidence on how much commercial devices differ in latency and how much is tolerable is still emerging. Thus, this paper will 1) present new technical measurement results using the method proposed by Zirn et al. 2015 and 2) assess perceptual consequences of technical latency mismatch based on a review of literature on respective just noticeable differences.
**Methods**: The latency of the entire electric stimulation path for a Marvel CI (Advanced Bionics) was obtained by summing EABR wave V latencies evoked on different intracochlear sites as published by Zirn et al. 2015 and technical measurements of the group delay of the sound processor. The setup consisted of equipment which are available in most CI clinics: an oscilloscope, an acoustic sound source, a speech processor and a reference implant. In order to quantify the mismatch for bimodal CI recipients, the entire ABR wave V latency of the electric stimulation was compared with respective latencies for acoustic stimulation with hearing aids.
**Results**: : The ABR latencies of the Marvel CI are 16.0 ms, 14.3 ms, 13.0 ms, and 11.7 ms at 500 Hz, 1 kHz, 2 kHz and 4 kHz respectively. When compared to a typical FFT-based hearing aid, a latency mismatch between 0 and 2 ms depending on frequency can be observed. This latency mismatch is clearly below the just noticeable difference reported for bimodal CI recipients of 8 – 10 ms.
**Conclusion:** Reliable latency measurements can be conducted in CI clinics following the method proposed by Zirn et al. For the Marvel CI speech processor the latency mismatch is within tolerable limits for bimodal users of most modern hearing aids.

Assessment of Device Delay Mismatch in Bimodal Cochlear Implant Recipients

It is with great pleasure and enthusiasm, that on behalf of the Cochlear Implant centers of the Radboud UMC in Nijmegen and Erasmus MC Sophia Children’s Hospital in Rotterdam to invite you to attend the 16th European Symposium on Pediatric Cochlear Implantation to Rotterdam, the Netherlands in 2023.

Yours sincerely, on behalf of the CI Centers at Radboud UMC and Erasmus MC,