The middle ear consists of the tympanic membrane and the ossicles, and ensures the transduction of sound from the auditory canal to the inner ear. Thus, diseases of the middle ear are often accompanied by hearing loss, especially in case of Eustachian tube dysfunction, acute or chronic otitis media, or otosclerosis. In the clinical routine, the diagnosis of pathological alterations in the middle ear is carried out using otoscopy or ear microscopy, audiometry, and tympanometry in order to assess morphological and functional changes of the middle ear.

Most commonly, autologous grafts are used in tympanic membrane (TM) reconstruction. However, apart from the limited availability and the increased surgical risk, they cannot replicate the full functionality of the human TM properly. Hence, biomimetic synthetic TM implants have been developed in our project to overcome these drawbacks. These innovative TM implants are made from synthetic biopolymer polycaprolactone (PCL) and silk fibroin (SF) by electrospinning technology. Static and dynamic experiments have shown that the mechanical and oscillatory behavior of the TM implants can be tuned by adjusting the solution concentration, the SF and PCL mixing ratio and the electrospinning parameters. In addition, candidates for TM implants could have comparable acousto-mechanical properties to human TMs. Finally, these candidates were further validated in in vitro experiments by performing TM reconstruction in human cadaver temporal bones. The reconstructed TM with SF–PCL blend membranes fully recovered the acoustic vibration when the perforation was smaller than 50%. Furthermore, the handling, medium adhesion and transparency of the developed TM implants were similar to those of human TMs.

Optical coherence tomography (OCT) is an interferometric imaging technique based on near-infrared light that enables real-time volumetric tissue imaging with microscopic resolution and penetration depths of up to 2 mm. While OCT has been successfully commercialized in ophthalmology for diagnostics of the eye, the application of both morphologic and functional OCT imaging for hearing diagnostics has attracted significant interest in recent years.¹ This includes not only the tympanic membrane (TM)^2,3 but also the ossicular chain in the middle ear^{4 – 6} and the inner ear.^7,8

To determine the relation between stapedius reflex thresholds in cochlear implant users evoked once through direct electric stimulation on single channels (ESRT) and once through acoustic stimulati...