# Round Window Reinforcement-Induced Changes in Intracochlear Sound Pressure
## 5 Conclusions  
In the present study, we performed simultaneous ICSP measurements on HTBs to investigate the influence of RWM reinforcement on the sound pressure in the basal part of the ST and SV. The resulting pressure difference induces the traveling wave on the basilar membrane and, hence, is regarded as an important measure for hearing sensation.  
The experiments revealed RWM reinforcement-induced changes in ICSP within the low-frequency range (<2.2 kHz), with the largest effect in ST below 1 kHz. In ST, a sound pressure increase of up to 25 dB was observed after RWM reinforcement. In contrast to the literature, we could identify a considerably smaller pressure rise in SV (<10 dB). The effect of the RWM reinforcement on ICSP varied largely between the individual HTB samples. The poor repeatability was mainly attributed to the difficult handling of the reinforcement material during RWM reinforcement, together with the lack of a direct measurement of the RWM impedance after reinforcement. Suggestions for a more appropriate reinforcement material that could considerably improve the repeatability of the experiment were made. The question raised in the literature--whether an artificially or pathologically reinforced RWM may cause conductive hearing loss at low frequencies--cannot be conclusively answered by this study. However, some data indicate a drop in the pressure difference across the partition of almost 10 dB. If the phase shift between the pressure readings in SV and ST is neglected, the resulting \(P_{\text{DIFF}}\) can even drop by more than 20 dB after RWM reinforcement. This is in the range of the clinically observed low-frequency hearing loss that can occur after CI surgeries. To provide better evidence in this context, the methodology of RWM reinforcement and ICSP measurement would require further improvement to increase the reinforcement effectiveness and the repeatability of the experiment.  
**Author Contributions:** Conceptualization, F.P., L.P., N.L., and I.D.; methodology, N.L., L.P., A.D., M.C., and F.P.; software, L.P. and N.L.; formal analysis, N.L., J.G., and L.P.; resources, A.H., T.K., and F.P.; data curation, N.L., J.G., and S.T.; writing--original draft preparation, N.L.; writing--review and editing, L.P., F.P., S.T., A.D., M.C., and I.D.; visualization, N.L.; supervision, F.P., A.H., and T.K.; funding acquisition, T.K. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This research was funded by the European Union's Horizon 2020 research and innovation program under the [PERSON] grant agreement number 722046.  
**Institutional Review Board Statement:** The study was conducted according to the guidelines of the Declaration of Helsinki and approved by the local ethics committee, Canton of Zurich, Switzerland (KEK-ZH-Nr. 2014-0544, approved on 25 February 2015).  
**Informed Consent Statement:** Not applicable.  
**Acknowledgments:** The authors would like to thank [PERSON] for his contributions in the model simulation validation and result interpretation and valuable insights into the experimental results, as well as all the members of the \"Otology and Biomechanics of Hearing\" research group for their support.  
**Conflicts of Interest:** The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analysis, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.