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Apart from material characteristics, the sound transmission properties of the reconstructed tympanic membrane are strongly influenced by the reconstruction technique. The choice of the surgical technique should consider requirements based on mechanical stability and acoustic transfer characteristics of the transplant.

In the drilling procedure for a cochleostomy, the inner ear may be affected by very high SPLs, particularly if the endosteal membrane is left intact and comes into contact with the running burr. Of course, the resulting SPLs depend on the drilling speed and the size and characteristics of the burr (larger burrs cause higher SPLs); however, we are of the opinion that the cochlear function is at risk, anyway, if special precaution is not exercised. Even when working with reduced drilling speed, the surgeon should be aware of the high risk in the form of an acoustic trauma, which may endanger residual hearing. Recommendations in terms of "soft surgery" are given in the paper (e.g., the use of microhooks instead of a drill to remove the very last shell of bone covering the cochlea).

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In order to get a better insight into the function of the human middle ear it is necessary to simulate its dynamic behaviour by means of the finite-element method. Three-dimensional measurements of the surfaces of the tympanic membrane and of the auditory ossicles malleus, incus and stapes are carried out and geometrical models are created. On the basis of these data, finite-element models are constructed and the dynamic behaviour of the combinations tympanic membrane with malleus in its elastic suspensions and stapes with annular ligament is simulated. Natural frequencies and mode shapes are computed by modal analysis. These investigations showed that the ossicles can be treated as rigid bodies only in a restricted frequency range from 0 to 3.5 kHz.

Modern application methods of an active middle ear implant (VSB) open new therapeutic options for patients with various outer and middle ear diseases resulting in conductive or mixed hearing loss. Titanium couplers can help to couple the active middle ear implant in a standardized way to remnants of the ossicular chain or to the round window. Thus, the active middle ear implant has been established as an alternative treatment option for patients with mixed and conductive hearing. However, the heterogeneity of the studies published so far complicates the analysis of the audiometric results, and thus, the functional hearing gain after VSB implantation varies a lot.

The tympanic membrane (TM) transfers sound waves from the air into mechanical motion for the ossicular chain. This requires a high sensitivity to small dynamic pressure changes and resistance to large quasi-static pressure differences. The TM achieves this by providing a layered structure of about 100µm in thickness, a low flexural stiffness, and a high tensile strength. Chronically infected middle ears require reconstruction of a large area of the TM. However, current clinical treatment can cause a reduction in hearing. With the novel additive manufacturing technique of melt electrowriting (MEW), it is for the first time possible to fabricate highly organized and biodegradable membranes within the dimensions of the TM. Scaffold designs of various fiber composition are analyzed mechanically and acoustically. It can be demonstrated that by customizing fiber orientation, fiber diameter, and number of layers the desired properties of the TM can be met. An applied thin collagen layer seals the micropores of the MEW-printed membrane while keeping the favorable mechanical and acoustical characteristics. The determined properties are beneficial for implantation, closely match those of the human TM, and support the growth of a neo-epithelial layer. This proves the possibilities to create a biomimimetic TM replacement using MEW. IntroductionDefects of the tympanic membrane (TM) have many causes, ranging from injuries to chronic otitis media (COM). In the

The aim of the study was to investigate the validity of the avian middle ear model for researching the tympanoplasty mechanics. We studied the morphological details, acoustic transmission and quasi-static behavior of the ostrich tympano-ossicular system. The stained specimens of the ostrich middle ear were examined under a light microscope. The sound transfer function and quasi-static performance of the ostrich middle ear were evaluated using laser Doppler vibrometry. The application of pressure to the tip of the extracolumella causes a buckling movement of the ossicle between the cartilaginous and bony parts. Histologically, the intracolumellar connection can be identified as a junction zone between bone and hyaline cartilage. Sound conduction through the human middle ear is less effective than it is through the ostrich middle ear. The greatest difference (35 dB) was observed in the low-frequency region. Because the extracolumella bends, the medial displacements of the eardrum were not fully transmitted to the footplate. The amplitude of the ostrich columella footplate quasi-static medial displacements significantly exceeded that of the human footplate in both intact and reconstructed middle ears. The ostrich middle ear is a suitable model for designing total ossicular replacement implants. The main protective mechanism in the ostrich middle ear under quasi-static stress is a buckling movement of the extracolumella. The total ossicular prostheses of the new generation should contain an elastic element that allows an adaptation to greater quasi-static eardrum movements.