# Comparison of the Sensitivity of Various Fibers in Distributed Acoustic Sensing
## 5 Conclusions  
In this study, the acoustic sensitivity of six types of specialty optical fibers was tested using a DAS setup and compared to that of the widely used standard telecommunications fiber, Corning SMF-28. The results showed that some fibers exhibited higher acoustic sensitivity than \"Fiber 1\", while others demonstrated lower sensitivity. The experimental data align closely with theoretical estimations of the fibers' acoustic sensitivities. Some samples displayed frequency-independent acoustic sensitivity relative to \"Fiber 1\", while others showed sensitivity focused within specific frequency ranges. The most notable result was observed in the polyimide-coated fiber with coating defects, while the copper-coated single-mode fiber exhibited the lowest total acoustic sensitivity. Explanations for the performance of each FUT have been provided.  
Based on these results, recommendations for optimizing DASs for new applications have been outlined. For instance, the Tefzel-DeSolite coated fiber is suitable for detecting acoustic frequencies below 2500 Hz, functioning as an intrinsic low-pass filter within DAS systems. Anisotropic Panda fiber can enhance the accurate reconstruction of the acoustic signal frequency spectrum compared to \"Fiber 1\". A single-mode fiber with a polyimide coating and inhomogeneities in that coating offers higher acoustic sensitivity than \"Fiber 1\" across frequencies from 100 to 7000 Hz, even without coating defects, although its sensitivity is slightly lower than that of \"Fiber 5\".  
For applications requiring protection from external acoustic perturbations, the Tefzel-DeSolite coated fiber with a 900 um outer diameter is recommended if disturbances occur predominantly above 2500 Hz, while a Copper-Carbon coating is preferable if disturbances span the 100 to 7000 Hz range.  
In summary, this study advances the understanding of the acoustic properties of various fibers and fiber coatings, supporting the adaptation of DAS technology to meet new industry monitoring needs, ultimately contributing to broader affordability and adoption.  
Conceptualization and project administration, Y.A.K.; supervision and project administration, D.A.K., V.V.K. and V.A.M.; writing--review and editing, and validation, A.A.F.; software, formal analysis, investigation, writing--original draft preparation, A.T.T.; methodology and data curation, D.C. All authors have read and agreed to the published version of the manuscript.  
Sections 3 and 4 were performed as a part of State Assignment No. 122031100058-3; Sections 2.2 and 2.3 were carried out under agreement No. 13 GUES18/90781 dated 18 December 2023 with the Foundation for Assistance to Small Innovative Enterprises. Sections 2.1 and 2.4 were supported by the Russian Science Foundation (Grant No. 23-79-30017); Sections 1 and 5 were carried out within the framework of State Assignment No. 124020600009-2.  
Not applicable.  
The data reported in this manuscript are available on request from the corresponding author.  
The authors declare no conflicts of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.  
The following abbreviations are used in this manuscript: