Periodic Reporting for period 1 - READIHEAR (Rehabilitation and Diagnosis of Hearing Loss based on Electric Acoustic Interaction)
Reporting period: 2022-12-01 to 2025-05-31
Hearing loss is the most prevalent sensory deficit in the elderly and increasingly poses serious social and health challenges. Cochlear implants (CIs), which stimulate the auditory nerve via electrodes in the cochlea, are now being used in individuals with residual low-frequency hearing. These patients often experience substantial improvements in speech perception through electric-acoustic stimulation, though outcomes vary and some do not benefit. Therefore, it is highly desirable to create objective diagnostics to assess acoustic low-frequency hearing to indicate cochlear implantation, to monitor and preserve hearing during the implantation procedure and to understand the mechanisms related to electric-acoustic stimulation benefits.
READIHEAR investigates the fundamental mechanisms of interaction between electric and acoustic stimulation along the auditory pathway. This knowledge will underpin the development of next-generation diagnostic tools for hearing loss, integrating minimally invasive electric-acoustic stimulation for the first time. Furthermore, the project will evaluate a novel auditory prosthetic that exploits these interaction mechanisms via minimally invasive electrodes. These advancements aim to benefit individuals across the lifespan—from children, through improved diagnostics, to older adults, via innovative treatments for age-related hearing loss.
The scientific goals of READIHEAR are:
SC1. Peripheral and central characterization of electric-acoustic interaction from intra-cochlear electric stimulation.
SC2. Peripheral and central characterization of electric-acoustic interaction from extra-cochlear electric stimulation.
SC3. Computational model of electric-acoustic interaction for intra- and extra-cochlear electric stimulation.
SC4. Develop/assay an auditory diagnostic device for hearing loss below 500 Hz based on electric-acoustic interaction.
SC5. Develop/assay an auditory prosthesis to restore high-frequency hearing based on electric-acoustic interaction.
READIHEAR investigates the fundamental mechanisms of interaction between electric and acoustic stimulation along the auditory pathway. This knowledge will underpin the development of next-generation diagnostic tools for hearing loss, integrating minimally invasive electric-acoustic stimulation for the first time. Furthermore, the project will evaluate a novel auditory prosthetic that exploits these interaction mechanisms via minimally invasive electrodes. These advancements aim to benefit individuals across the lifespan—from children, through improved diagnostics, to older adults, via innovative treatments for age-related hearing loss.
The scientific goals of READIHEAR are:
SC1. Peripheral and central characterization of electric-acoustic interaction from intra-cochlear electric stimulation.
SC2. Peripheral and central characterization of electric-acoustic interaction from extra-cochlear electric stimulation.
SC3. Computational model of electric-acoustic interaction for intra- and extra-cochlear electric stimulation.
SC4. Develop/assay an auditory diagnostic device for hearing loss below 500 Hz based on electric-acoustic interaction.
SC5. Develop/assay an auditory prosthesis to restore high-frequency hearing based on electric-acoustic interaction.
We have made significant advances in enhancing auditory diagnosis and designing innovative auditory prostheses. Our research has led to the creation of new methods and prototypes that were used for evaluation in CI users and normal-hearing subjects. Key achievements include:
Related to SC1:
- Demonstrated integration between electric and acoustic stimulation (across ears) at cortical level using speech stimuli and short stimuli (Dolhopiatenko and Nogueira, Frontiers 2023; Dolhopiatenko et al., Hearing Research 2024; Dolhopiatenko and Nogueira, Hearing Research 2025).
- Designed and validated a novel measure to assess cortically evoked potentials to phonemes from continuous speech with electric stimulation. Now, this measure can be extended to electric-acoustic interaction to investigate central integration of phonemes with electric and acoustic stimulation (Aldag and Nogueira, Scientific Reports 2023).
Related to SC2:
- Demonstrated that interaction between low-frequency acoustic stimulation and electric stimulation delivered through a CI electrode placed at or close to the round window exists and that it can be measured through behavioral responses. This opens the possibility to assess low-frequency residual hearing through electric-acoustic interaction (Hinz et al., ARO 2025).
- First electrophysiological measures have been conducted to assess whether electric-acoustic interaction can be measured electrophysiologically (Nogueira et al., ARO 2025).
Related to SC3:
- Designed a computational modeling framework to simulate the current spread and activation of the auditory nerve for electric stimulation through a CI or through extracochlear electrodes in the middle ear or external ear canal (e.g. Kipping et al., ARO 2025).
- Investigated electric-acoustic interaction in electrophysiological responses through the computational modeling framework (Kipping et al., IEEE TMBE 2024; Kipping et al., ARO 2025;).
- Evaluated possible electrophysiological measures of neural survival using the computational modeling framework (Zhang et al., arXiv 2025).
- Investigated loudness perception, spectral modulation detection, and speech reception performance of CI users using the computational modeling framework (Kipping et al., ICBT 2023; Alvarez et al., Frontiers 2023; Alvarez et al., arXiv 2025).
Related to SC4:
- Designed the research interface to deliver electric and acoustic stimulation that serves as the basis for the subprojects P1, P3 and P4 (Nogueira, DGA 2024; Hinz et al., ARO 2025). Clinical approval to conduct experiments in hearing-impaired subjects has been granted and first pilot experiments are running.
- Designed and evaluated a novel method for measuring electrophysiological responses that improves accuracy at hearing threshold with respect to current available measures (Krüger et al., JASA 2025, under review).
Related to SC5:
- Designed and evaluated a sound coding strategy combining low-frequency acoustic hearing with basal electric stimulation, enhancing speech reception and logatome identification (Nogueira, CIAP 2023; Nogueira, DGA 2024).
- Designed a research interface prototype consisting of an electric current source, an acoustic stimulator, and a controller for the stimulation through a graphical user interface, termed READISTIM, for extra-cochlear electric and acoustic stimulation. READISTIM can be connected to a physiological amplifier to assess how low-frequency acoustic stimulation masks electrically evoked auditory brainstem responses (ABRs) (Hinz et al., ARO 2025) and serves as a first version of the diagnostic device defined in P3.
Related to SC1:
- Demonstrated integration between electric and acoustic stimulation (across ears) at cortical level using speech stimuli and short stimuli (Dolhopiatenko and Nogueira, Frontiers 2023; Dolhopiatenko et al., Hearing Research 2024; Dolhopiatenko and Nogueira, Hearing Research 2025).
- Designed and validated a novel measure to assess cortically evoked potentials to phonemes from continuous speech with electric stimulation. Now, this measure can be extended to electric-acoustic interaction to investigate central integration of phonemes with electric and acoustic stimulation (Aldag and Nogueira, Scientific Reports 2023).
Related to SC2:
- Demonstrated that interaction between low-frequency acoustic stimulation and electric stimulation delivered through a CI electrode placed at or close to the round window exists and that it can be measured through behavioral responses. This opens the possibility to assess low-frequency residual hearing through electric-acoustic interaction (Hinz et al., ARO 2025).
- First electrophysiological measures have been conducted to assess whether electric-acoustic interaction can be measured electrophysiologically (Nogueira et al., ARO 2025).
Related to SC3:
- Designed a computational modeling framework to simulate the current spread and activation of the auditory nerve for electric stimulation through a CI or through extracochlear electrodes in the middle ear or external ear canal (e.g. Kipping et al., ARO 2025).
- Investigated electric-acoustic interaction in electrophysiological responses through the computational modeling framework (Kipping et al., IEEE TMBE 2024; Kipping et al., ARO 2025;).
- Evaluated possible electrophysiological measures of neural survival using the computational modeling framework (Zhang et al., arXiv 2025).
- Investigated loudness perception, spectral modulation detection, and speech reception performance of CI users using the computational modeling framework (Kipping et al., ICBT 2023; Alvarez et al., Frontiers 2023; Alvarez et al., arXiv 2025).
Related to SC4:
- Designed the research interface to deliver electric and acoustic stimulation that serves as the basis for the subprojects P1, P3 and P4 (Nogueira, DGA 2024; Hinz et al., ARO 2025). Clinical approval to conduct experiments in hearing-impaired subjects has been granted and first pilot experiments are running.
- Designed and evaluated a novel method for measuring electrophysiological responses that improves accuracy at hearing threshold with respect to current available measures (Krüger et al., JASA 2025, under review).
Related to SC5:
- Designed and evaluated a sound coding strategy combining low-frequency acoustic hearing with basal electric stimulation, enhancing speech reception and logatome identification (Nogueira, CIAP 2023; Nogueira, DGA 2024).
- Designed a research interface prototype consisting of an electric current source, an acoustic stimulator, and a controller for the stimulation through a graphical user interface, termed READISTIM, for extra-cochlear electric and acoustic stimulation. READISTIM can be connected to a physiological amplifier to assess how low-frequency acoustic stimulation masks electrically evoked auditory brainstem responses (ABRs) (Hinz et al., ARO 2025) and serves as a first version of the diagnostic device defined in P3.
A new computational model of evoked compound action potentials to acoustic and electric stimulation has been designed and published as open source. In terms of knowledge transfer, the computational modeling framework of the evoked compound action potential (Kipping et al., IEEE TBME 2024) has been published in open source through GitLab (https://gitlab.gwdg.de/apg/eas-cap-model-2024(opens in new window)). Extensions of this framework are being published as well as open source (Alvarez et al., arXiv 2025; Zhang et al., arXiv 2025). The model will be further validated by comparing different types of electrophysiological data recorded from CI subjects with predictions from the computational model. The model aims at providing a comprehensive understanding of the electrode nerve interface in CI subjects with and without residual hearing combining a 3D realistic anatomy of the cochlea and the auditory nerve, voltage spread in the cochlea, hair cell activity and neural activity.
During the first reporting period, we have successfully demonstrated that acoustic stimulation interacts with electric stimulation along the auditory pathway. This has been demonstrated through a novel methodology that combines psychoacoustic and electrophysiological measures combined with a computational model. From the fundamental finding that electric and acoustic interaction exists, we have submitted a patent application to create a novel diagnostic and treatment device as described in scientific goals SC4 and SC5. Next steps include a clinical trial in CI candidates where acoustic masking will be used to assess their low frequency residual hearing. This measure has potential as a new diagnostic of very low frequency hearing.
During the first reporting period, we have successfully demonstrated that acoustic stimulation interacts with electric stimulation along the auditory pathway. This has been demonstrated through a novel methodology that combines psychoacoustic and electrophysiological measures combined with a computational model. From the fundamental finding that electric and acoustic interaction exists, we have submitted a patent application to create a novel diagnostic and treatment device as described in scientific goals SC4 and SC5. Next steps include a clinical trial in CI candidates where acoustic masking will be used to assess their low frequency residual hearing. This measure has potential as a new diagnostic of very low frequency hearing.