Research

Individualized cochlear implant therapy

We investigate cochlear implant (CI) telemetry, i.e. the measurement of electrical impedances and neural responses, as a source of objective information on the state of the cochlea during and after implantation. We have shown that impedance telemetry allows electrode insertion depth to be estimated without ionizing radiation, including in pediatric patients, and we have decomposed the measured impedance into electrode, tissue and far-field components. In an ongoing project, impedance-based localization of the electrode array is evaluated in a clinical cohort. Further work addresses tissue-response models for predicting hearing preservation, image-based modelling of individual far-field resistance, and the relation between impedance components and ECAP signal artifacts.

Cochlear implant insertion and intraoperative monitoring

We study the mechanics of electrode array insertion and develop methods for monitoring insertion during surgery, with the aim of reducing insertion trauma and preserving residual hearing. Work includes in-vitro identification of vulnerable phases of insertion, metronome-guided manual insertion, intraoperative electrophysiological and pressure-based monitoring. The ongoing IMT study evaluates monitoring of electrode insertion during cochlear implantation.

Pediatric hearing diagnostics

We develop and evaluate methods for the objective and child-friendly assessment of hearing.

Implant audiometry (INSITU). In unilateral and asymmetric hearing loss, hearing in the implanted ear is difficult to assess in isolation: the contralateral ear contributes during sound-field testing, and masking procedures differ considerably between clinics. In a prospective study, we compare direct audio input to the implant processor with conventional sound-field testing in patients aged eight years and older cochlear implants. Outcomes are aided thresholds, speech recognition in quiet and in noise, and subjective preference. The approach is additionally being used clinically in children from two years of age.

Speech testing in noise (BOLKISA). The Oldenburg Children’s Sentence Test (OLKISA) is an established adaptive test of speech recognition in noise, but its 50 % intelligibility target is often strenuous for children. BOLKISA is a Bayesian adaptive version that estimates, in addition to the speech reception threshold, the slope of the psychometric function. We validate it against OLKISA in primary-school children, comparing normal-hearing children and children with auditory processing disorder.

Hearing screening (KIKIS). We evaluate objective hearing screening at the school entry examination in the City of Munich (planned n = 1,000). Screening in daycare settings is a longer-term goal.

Imaging and cochlear morphology

We combine morphometric analysis of the inner ear with computational and experimental fluid dynamics in cochlea-like geometries to study geometry-dependent aspects of cochlear mechanics. The COMORPH study relates cochlear anatomy to function by combining hearing tests with MRI-based image analysis. Within this project, a high-resolution MRI sequence of the inner ear was developed with an acquisition time of less than five minutes. The results are intended to inform surgical planning and the design of CI electrode arrays.

Objective Tinnitus Diagnostics

Tinnitus, i.e., the perception of sound in the absence of an external acoustic stimulus, is a poorly understood symptom. The prevalence of tinnitus is estimated to be 10-15% of the general population and is expected to increase due to demographic developments. In our group, we work on objective methods for tinnitus assessment and classification. These would enable clinicians to quantify treatment outcomes of existing interventions and facilitate the development of novel therapies. One approach to objective tinnitus assessment is the identification of neuronal correlates in electroencephalography (EEG).