The purpose of this NIDCD initiative is to encourage research in the development, characterization, and reproducibility/reliability of human auditory and vestibular organoids. Proposals investigating animal organoids are allowable but only if accompanying comparative or other integrated companion studies with human organoids. Singular animal organoid studies alone are not responsive to this funding opportunity. This funding opportunity encourages innovative, reproducible, and novel methodologies and technologies that will drive the reproducibility and holistic longevity of hearing/balance sensory organoids as model systems. The development of novel tools to deliver genes, proteins, molecules, and synthetics that might lead to the successful expansion and longer-term survivability of organoid populations in a stable, reliable, and reproducible manner is highly encouraged. Subsequent characterization of the organoid platforms must be shown to mimic and recapitulate the native correlative biological function. Applications that provide approaches that remove current barriers and lessen challenges to improve current reproducibility and stability are highly encouraged. Applications that have breakthrough approaches and technologies using human auditory/vestibular organoids are highly encouraged.