Algo suena en el campus de Gandia

Picó Vila, R. (2020). Algo suena en el campus de Gandia. Revista de Acústica. 51(1-2):32-36. http://hdl.handle.net/10251/176138S3236511-

Increasing the Insertion Loss of Sonic Crystal Noise Barriers with Helmholtz Resonators

[EN] Helmholtz resonators (HRs) have the advantage of extending and improving their insulating capacity when used as scatterers in noise barriers made of periodic media, such as sonic crystals (SCs). However, the interaction between multiple Bragg scattering and local resonance phenomena can increase or decrease the insulation of the barrier depending on its design. In the present work, we numerically investigate the factors that determine how such interferences occur and the specific conditions to increase the insertion loss of sonic crystal noise barriers (SCNBs) made of cylindrical scatterers with HRs. Two factors are crucial for the variation of the isolation of the barrier in the Bragg-bandgap (Bragg-BG): the orientation of the resonator mouth with respect to the incident wave, and the resonance frequency of the resonator with respect to the central frequency of the Bragg-BG. Based on this phenomenon, we propose a sonic crystal noise barrier consisting of scatterers with two Helmholtz resonators. The insertion loss of the structure is determined numerically and shows an increase of 20 dB at the BG compared to a conventional barrier with cylindrical scatterers.This work was supported by the Spanish Ministry of Economy and Innovation (MINECO) and the European Union FEDER (project PID2019-109175GB-C22).Redondo, J.; Ramírez-Solana, D.; Picó Vila, R. (2023). Increasing the Insertion Loss of Sonic Crystal Noise Barriers with Helmholtz Resonators. Applied Sciences. 13(6). https://doi.org/10.3390/app1306366213

Directional Ultrasound Source for Solid Materials Inspection: Diffraction Management in a Metallic Phononic Crystal

[EN] In this work, we numerically investigate the diffraction management of longitudinal elastic waves propagating in a two-dimensional metallic phononic crystal. We demonstrate that this structure acts as an "ultrasonic lens", providing self-collimation or focusing effect at a certain distance from the crystal output. We implement this directional propagation in the design of a coupling device capable to control the directivity or focusing of ultrasonic waves propagation inside a target object. These effects are robust over a broad frequency band and are preserved in the propagation through a coupling gel between the "ultrasonic lens" and the solid target. These results may find interesting industrial and medical applications, where the localization of the ultrasonic waves may be required at certain positions embedded in the object under study. An application example for non-destructive testing with improved results, after using the ultrasonic lens, is discussed as a proof of concept for the novelty and applicability of our numerical simulation study.H. Selim, J. Trull, C. Cojocaru, and R. Pico acknowledge partial support from the Spanish Ministry of Economy and Innovation (MINECO) and European Union FEDER through project PID2019-109175GB-C22. H. Selim, J. Trull, and C. Cojocaru acknowledge partial support from US Army Research, Development, and Engineering Command (RDECOM) through project W911NF-16-1-0563.Selim, H.; Picó Vila, R.; Trull, J.; Delgado Prieto, M.; Cojocaru, C. (2020). Directional Ultrasound Source for Solid Materials Inspection: Diffraction Management in a Metallic Phononic Crystal. Sensors. 20(21):1-18. https://doi.org/10.3390/s20216148S118202

Walidacja parametrów dla klasyfikacji akustyczno-organologicznej timple

The timple is a small traditional cordophone originary from the Canarian archipelago (one of the outermost regions of the Kingdom of Spain). Because of its morphology, it is similar tothe ukulele or the guitarro, but differs with them in that the back of the timple is curved. This research work addresses the study of timple from two perspectives: organological and acoustic. In order to carry out the study, instruments provided by La Casa – Museo del Timple located in the Municipality of Teguise on the island of Lanzarote (Canary Islands) were analyzed. In order to structure the analysis of the present research a cataloguing system to classify groups of timples isproposed and validated. In it, different aspects are taken into consideration such as the functionality or the acoustic response of each group for its definition.</p

Validación de parámetros para la clasificación acústica-organológica del timple

The timple is a small traditional cordophone originary from the Canarian archipelago (one of the outermost regions of the Kingdom of Spain). Because of its morphology, it is similar tothe ukulele or the guitarro, but differs with them in that the back of the timple is curved. This research work addresses the study of timple from two perspectives: organological and acoustic. In order to carry out the study, instruments provided by La Casa – Museo del Timple located in the Municipality of Teguise on the island of Lanzarote (Canary Islands) were analyzed. In order to structure the analysis of the present research a cataloguing system to classify groups of timples isproposed and validated. In it, different aspects are taken into consideration such as the functionality or the acoustic response of each group for its definition.El timple es un pequeño cordófono tradicional del archipiélago canario (región ultraperiférica del Reino de España). Por su morfología, es semejante al ukelele o al guitarró, pero difiereen que la parte trasera del timple es curva. En este trabajo de investigación se aborda el estudio del timple desde dos perspectivas: organológica y acústica. Para la realización del estudio se analizaron instrumentos cedidos por La Casa – Museo del Timple, ubicada en el municipio de Teguise en la isla de Lanzarote (Islas Canarias). Con objeto de estructurar el análisis de la investigación se propone y se valida un sistema de catalogación por grupos de timples en el que se tienen en consideración distintos aspectos como la funcionalidad y respuesta acústica de cada grupo para su definición

Monitoring the setting of calcium sulfate bone-graft substitute using ultrasonic backscattering

[EN] We report a method to monitor the setting process of bone-graft substitutes (calcium sulfate) using ultrasonic backscattering techniques. Analyzing the backscattered fields using a pulse-echo technique, we show that it is possible to dynamically describe the acoustic properties of the material which are linked to its setting state. Several experiments were performed to control the setting process of calcium sulfate using a 3.5-MHz transducer. The variation of the apparent integrated backscatter (AIB) with time during the setting process is analyzed and compared with measurements of the speed of sound (SOS) and temperature of the sample. The correlation of SOS and AIB allows us to clearly identify two different states of the samples, liquid and solid, in addition to the transition period. Results show that using backscattering analysis, the setting state of the material can be estimated with a threshold of 15 dB. This ultrasonic technique is indeed the first step to develop real-time monitoring systems for time-varying complex media as those present in bone regeneration for dental implantology applications.This work was supported in part by Universitat Politecnica de Valencia (UPV) and Fundacion para el Fomento de la Investigacion Sanitaria y Biomedica de la Comunitat Valenciana (FISABIO) through the project OSEODENT under Grant POLISABIO 2018, in part by the European Union, in part by Generalitat Valenciana through the European Regional Development Fund Program under Grant IDIFEDER/2018/022, and in part by the Agencia Valenciana de la Innovacio through the Unitat Cientifica d'Innovacio Empresarial under Grant INNCON00/18/9. The work of N. Jimenez was supported by Generalitat Valenciana under Grant APOSTD/2017/042.Rodríguez-Sendra, J.; Jimenez, N.; Picó Vila, R.; Faus, J.; Camarena Femenia, F. (2019). Monitoring the setting of calcium sulfate bone-graft substitute using ultrasonic backscattering. IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control. 66(10):1658-1666. https://doi.org/10.1109/TUFFC.2019.2926827S16581666661

Angular bandgaps in sonic crystals: evanescent waves and spatial complex dispersion relation

Phononic crystals are artificial materials made of a periodic distribution of solid scatterers embedded into a solid host medium with different physical properties. An interesting case of phononic crystals, known as sonic crystals (SCs), appears when the solid scatterers are periodically embedded in a fluid medium. In SCs only longitudinal modes are allowed to propagate and both the theoretical and the experimental studies of the properties of the system are simplified without loss of generality. The most celebrated property of these systems is perhaps the existence of spectral band gaps. However, the periodicity of the system can also affect to the spatial dispersion, making possible the control of the diffraction inside these structures. In this work we study the main features of the spatial dispersion in SCs from a novel point of view taking into account the evanescent properties of the system, i.e., studying the complex spatial dispersion relations. The evanescent behavior of the propagation of waves in the angular band gaps are theoretically and experimentally observed in this work. Both the numerical predictions and the experimental results show the presence of angular band gaps in good agreement with the complex spatial dispersion relation. The results shown in this work are independent of the spatial scale of the structure, and in principle the fundamental role of the evanescent waves could be also expected in micro- or nanoscale phononic crystals.This work was supported by MCI Secretaria de Estado de Investigacion (Spanish government) and the FEDER funds, under Grant Nos. MAT2009-09438, FIS2011-29734-C02-02, and from Generalitat Valencia through Project No. GV/2011/055. V.R.G. is grateful for the support of "Programa de Contratos Post-Doctorales con Movilidad UPV (CEI-01-11)." We acknowledge the Centro de Tecnologias Fisicas: Acustica, Materiales y Astrofisica and the Sonic Crystal Technologies Research Group of the Universitat Politecnica de Valencia for the use of the anechoic chamber and the 3DReAMS respectively.Romero García, V.; Picó Vila, R.; Cebrecos Ruiz, A.; Staliünas, K.; Sánchez Morcillo, VJ. (2013). Angular bandgaps in sonic crystals: evanescent waves and spatial complex dispersion relation. Journal of Vibration and Acoustics. 135(4):410121-410126. https://doi.org/10.1115/1.4023832S4101214101261354Yablonovitch, E. (1987). Inhibited Spontaneous Emission in Solid-State Physics and Electronics. Physical Review Letters, 58(20), 2059-2062. doi:10.1103/physrevlett.58.2059John, S. (1987). Strong localization of photons in certain disordered dielectric superlattices. Physical Review Letters, 58(23), 2486-2489. doi:10.1103/physrevlett.58.2486Ruffa, A. A. (1992). Acoustic wave propagation through periodic bubbly liquids. 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Spectral gaps for electromagnetic and scalar waves: Possible explanation for certain differences. Physical Review B, 50(5), 3393-3396. doi:10.1103/physrevb.50.3393Martínez-Sala, R., Sancho, J., Sánchez, J. V., Gómez, V., Llinares, J., & Meseguer, F. (1995). Sound attenuation by sculpture. Nature, 378(6554), 241-241. doi:10.1038/378241a0Sánchez-Pérez, J. V., Caballero, D., Mártinez-Sala, R., Rubio, C., Sánchez-Dehesa, J., Meseguer, F., … Gálvez, F. (1998). Sound Attenuation by a Two-Dimensional Array of Rigid Cylinders. Physical Review Letters, 80(24), 5325-5328. doi:10.1103/physrevlett.80.5325Kushwaha, M. S. (1997). Stop-bands for periodic metallic rods: Sculptures that can filter the noise. Applied Physics Letters, 70(24), 3218-3220. doi:10.1063/1.119130Robertson, W. M., & Rudy, J. F. (1998). Measurement of acoustic stop bands in two-dimensional periodic scattering arrays. The Journal of the Acoustical Society of America, 104(2), 694-699. doi:10.1121/1.423344Khelif, A., Choujaa, A., Djafari-Rouhani, B., Wilm, M., Ballandras, S., & Laude, V. (2003). Trapping and guiding of acoustic waves by defect modes in a full-band-gap ultrasonic crystal. Physical Review B, 68(21). doi:10.1103/physrevb.68.214301Sanchez-Perez, J. V., Rubio, C., Martinez-Sala, R., Sanchez-Grandia, R., & Gomez, V. (2002). Acoustic barriers based on periodic arrays of scatterers. Applied Physics Letters, 81(27), 5240-5242. doi:10.1063/1.1533112Romero-García, V., Sánchez-Pérez, J. V., & Garcia-Raffi, L. M. (2011). Tunable wideband bandstop acoustic filter based on two-dimensional multiphysical phenomena periodic systems. Journal of Applied Physics, 110(1), 014904. doi:10.1063/1.3599886Qiu, C., Liu, Z., Shi, J., & Chan, C. T. (2005). Directional acoustic source based on the resonant cavity of two-dimensional phononic crystals. Applied Physics Letters, 86(22), 224105. doi:10.1063/1.1942642Qiu, C., & Liu, Z. (2006). Acoustic directional radiation and enhancement caused by band-edge states of two-dimensional phononic crystals. Applied Physics Letters, 89(6), 063106. doi:10.1063/1.2335975Sigalas, M. M. (1998). Defect states of acoustic waves in a two-dimensional lattice of solid cylinders. Journal of Applied Physics, 84(6), 3026-3030. doi:10.1063/1.368456Tanaka, Y., Yano, T., & Tamura, S. (2007). Surface guided waves in two-dimensional phononic crystals. Wave Motion, 44(6), 501-512. doi:10.1016/j.wavemoti.2007.02.009Vasseur, J. O., Deymier, P. A., Djafari-Rouhani, B., Pennec, Y., & Hladky-Hennion, A.-C. (2008). Absolute forbidden bands and waveguiding in two-dimensional phononic crystal plates. Physical Review B, 77(8). doi:10.1103/physrevb.77.085415Zhao, Y.-C., & Yuan, L.-B. (2008). Characteristics of multi-point defect modes in 2D phononic crystals. Journal of Physics D: Applied Physics, 42(1), 015403. doi:10.1088/0022-3727/42/1/015403Wu, L.-Y., Chen, L.-W., & Liu, C.-M. (2009). Experimental investigation of the acoustic pressure in cavity of a two-dimensional sonic crystal. Physica B: Condensed Matter, 404(12-13), 1766-1770. doi:10.1016/j.physb.2009.02.025Hussein, M. I. (2009). Theory of damped Bloch waves in elastic media. Physical Review B, 80(21). doi:10.1103/physrevb.80.212301Romero-García, V., Vasseur, J. O., Hladky-Hennion, A. C., Garcia-Raffi, L. M., & Sánchez-Pérez, J. V. (2011). Level repulsion and evanescent waves in sonic crystals. Physical Review B, 84(21). doi:10.1103/physrevb.84.212302Farzbod, F., & Leamy, M. J. (2011). Analysis of Bloch’s Method in Structures with Energy Dissipation. Journal of Vibration and Acoustics, 133(5). doi:10.1115/1.4003943Laude, V., Moiseyenko, R. P., Benchabane, S., & Declercq, N. F. (2011). Bloch wave deafness and modal conversion at a phononic crystal boundary. AIP Advances, 1(4), 041402. doi:10.1063/1.3675828Moiseyenko, R. P., Herbison, S., Declercq, N. F., & Laude, V. (2012). Phononic crystal diffraction gratings. Journal of Applied Physics, 111(3), 034907. doi:10.1063/1.3682113Romero-García, V., Vasseur, J. O., Garcia-Raffi, L. M., & Hladky-Hennion, A. C. (2012). Theoretical and experimental evidence of level repulsion states and evanescent modes in sonic crystal stubbed waveguides. New Journal of Physics, 14(2), 023049. doi:10.1088/1367-2630/14/2/023049Sánchez-Morcillo, V. J., Staliunas, K., Espinosa, V., Pérez-Arjona, I., Redondo, J., & Soliveres, E. (2009). Propagation of sound beams behind sonic crystals. Physical Review B, 80(13). doi:10.1103/physrevb.80.134303Rakich, P. T., Dahlem, M. S., Tandon, S., Ibanescu, M., Soljačić, M., Petrich, G. S., … Ippen, E. P. (2006). Achieving centimetre-scale supercollimation in a large-area two-dimensional photonic crystal. 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G., Joannopoulos, J. D., & Pendry, J. B. (2003). Subwavelength imaging in photonic crystals. Physical Review B, 68(4). doi:10.1103/physrevb.68.045115Yang, S., Page, J. H., Liu, Z., Cowan, M. L., Chan, C. T., & Sheng, P. (2004). Focusing of Sound in a 3D Phononic Crystal. Physical Review Letters, 93(2). doi:10.1103/physrevlett.93.024301Ke, M., Liu, Z., Qiu, C., Wang, W., Shi, J., Wen, W., & Sheng, P. (2005). Negative-refraction imaging with two-dimensional phononic crystals. Physical Review B, 72(6). doi:10.1103/physrevb.72.064306Feng, L., Liu, X.-P., Chen, Y.-B., Huang, Z.-P., Mao, Y.-W., Chen, Y.-F., … Zhu, Y.-Y. (2005). Negative refraction of acoustic waves in two-dimensional sonic crystals. Physical Review B, 72(3). doi:10.1103/physrevb.72.033108Romero-García, V., Sánchez-Pérez, J. V., & Garcia-Raffi, L. M. (2010). Evanescent modes in sonic crystals: Complex dispersion relation and supercell approximation. Journal of Applied Physics, 108(4), 044907. doi:10.1063/1.3466988Laude, V., Achaoui, Y., Benchabane, S., & Khelif, A. (2009). Evanescent Bloch waves and the complex band structure of phononic crystals. Physical Review B, 80(9). doi:10.1103/physrevb.80.092301Romero-García, V., Sánchez-Pérez, J. V., & Garcia-Raffi, L. M. (2010). Propagating and evanescent properties of double-point defects in sonic crystals. New Journal of Physics, 12(8), 083024. doi:10.1088/1367-2630/12/8/083024Romero-García, V., Sánchez-Pérez, J. V., Castiñeira-Ibáñez, S., & Garcia-Raffi, L. M. (2010). Evidences of evanescent Bloch waves in phononic crystals. Applied Physics Letters, 96(12), 124102. doi:10.1063/1.3367739Romero-García, V., Garcia-Raffi, L. M., & Sánchez-Pérez, J. V. (2011). Evanescent waves and deaf bands in sonic crystals. AIP Advances, 1(4), 041601. doi:10.1063/1.3675801Li, J., & Chan, C. T. (2004). Double-negative acoustic metamaterial. 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Numerical modeling and experimental characterization of absorbent materials: professional competencies of the acoustic engineer

[ES] En este trabajo se desarrollan de forma numérica modelos empíricos que permiten conocer el comportamiento acústico de materiales utilizados en soluciones constructivas en la edificación. Este trabajo se engloba dentro del Máster Universitario en Ingeniería Acústica (MIA) de la Escuela Politécnica Superior de Gandía en la Universitat Politècnica de València. El ingeniero acústico, para conseguir todas las competencias que se exigen en la titulación, necesita conocer el comportamiento acústico de materiales, o soluciones acústicas, así como también necesita desarrollar herramientas de simulación numérica. Se propone, en este estudio, una evaluación numérica de modelos empíricos que permita al alumnado combinar competencias de asignaturas diferentes para alcanzar un objetivo común, ofreciendo así al alumnado herramientas multidisciplinares que debe utilizar en su incorporación al mundo laboral.[EN] In this work, empirical models are developed in numerical form that allow to know the acoustic behavior of materials used in constructive solutions in the building. This work is included within the Master’s Degree in Acoustic Engineering of the Higher Polytechnic School of Gandia at the Universitat Politècnica de València. The acoustic engineer, in order to achieve all the competencies required, needs to know the acoustic behavior of materials, or acoustic solutions, and it also needs to develop numerical simulation tools. In this study, it is proposed a numerical evaluation of empirical models that allow students to combine competences of different subjects to achieve a common goal, thus offering to the students multidisciplinary tools that should be used in their incorporation into the world of work.Este trabajo está subvencionado por el Ministerio de Economía e Innovación (MINECO) y por el Fondo Europeo (FEDER) a través del proyecto FIS2015-65998-C2-2 y por los proyectos GVA AICO/2016/060 y ACIF/2017/073 por la Consellería de Educación, Investigación, Cultura y Deporte de la Generalitat Valenciana y con el apoyo del Fondo Social Europeo (ESF).Atiénzar Navarro, R.; Picó Vila, R.; Rey Tormos, RMD. (2019). Modelización numérica y caracterización experimental de materiales absorbentes: competencias profesionales del ingeniero acústico. Modelling in Science Education and Learning. 12(2):111-124. https://doi.org/10.4995/msel.2019.10998OJS111124122Real decreto 314/2006, de 17 de marzo, por el que se aprueba el Código Técnico de la Edificación. BOE nº 74 de 28/03/2006.Código Técnico de la Edificación. Libro 11, Parte II. Documento básico DB-HR de Protección frente al ruido. España. Boletín Oficial del estado, 2009. 3º ed. https://www.codigotecnico.org/ (última visita 26-12-2018).Vidal Meló, A., del Rey Tormos, R., Sapena Piera, A., Roig Sala, B., Estruch Fuster, V. D., Boigues Planes, F. J., and Alba, J. (2014). Utilizando las matemáticas para resolver problemas de acústica de salas. Modelling in Science Education and Learning, vol. 7(1), ISSN 1988-3145 https://doi.org/10.4995/msel.2014.2083Vidal, A., Roig, B., Estruch, V. D., Boigues, F. J., del Rey, R., and Alba, J. (2013). Modelos de mapas topográficos y acústicos: del papel al ordenador. Modelling in Science Education and Learning, vol. 6(2), ISSN 1988-3145. https://doi.org/10.4995/msel.2013.1904Banyuls-Juan, X., Atiénzar-Navarro, R., and Picó, R. (2017). Simulación numérica de un conjunto de altavoces subwofers utilizando Elementos Finitos. Modelling in Science Education and Learning, vol. 10(2), pp. 203-210. https://doi.org/10.4995/msel.2017.7653http://www.upv.es/titulaciones/MUIA/menu_1015100c.html (última visita 26-12-2018). Estudios de máster en la Universitat Politècnica de València.COMSOL Multiphysics Modeling Guide. Versión Comsol 5.3a (2017).UNE-EN ISO 10534-2. (2002). Determination of sound absorption coefficient and impedance in impedances tubes. Part 2: Transfer-function method. Acoustics.Ingard, K. U., and Dear, T. A. (1985). Measurement Of Acoustic Flow Resistance. Journal of Sound and Vibration. Vol.103(4), pp. 567-572. https://doi.org/10.1016/S0022-460X(85)80024-9Delany, M. E., and Bazley, E. N. (1970). Acoustical properties of fibrous absorbent materials. Applied Acoustics, Vol. 3(2), pp. 105-116. https://doi.org/10.1016/0003-682X(70)90031-9Ramis, J., Alba, J., del Rey, R., Escuder, E., and Sanchís V. J. (2010). New absorbent material acoustic base on kenaf's fibre. Materiales de Construcción, Vol. 60(299), pp. 133-143. https://doi.org/10.3989/mc.2010.50809Ramis, J., del Rey, R., Alba, J., Godinho, L., and Carbajo, J. (2014). A model for acoustic absorbent materials derived from coconut fiber. Materiales de construcción, Vol. 64(313), pp. 1-7. https://doi.org/10.3989/mc.2014.00513Benito Muñoz, J. J., Álvarez Cabal, R., Ureña Prieto, F., Salete Casino, E., and Aranda Ortega, E. (2016). Introducción al método de los elementos finitos. UNED, Madrid.Courant, R., Friedrichs, K., and Lewy, H. (1967). On the partial difference equations of mathematical physics. IBM Journal of Research and Development. Vol. 11(2), pp. 215-234. https://doi.org/10.1147/rd.112.0215Romero-García, V., Theocharis, G., Richoux, O., and Pagneux, V. (2016). Use of complex frequency plane to design broadband and sub-wavelength absorbers. Journal of the Acoustical Society of America. Vol. 139(6), pp. 3395-3403. https://doi.org/10.1121/1.495070

Sound absorption of doped cotton textile fabrics with microcapsules

[ES] El desarrollo de nuevos tejidos textiles con microcápsulas depositadas en sus fibras está en auge dentro de la industria textil. El objetivo de este estudio se centra en analizar la influencia del dopaje de diferentes tejidos textiles de algodón con microcápsulas en el coeficiente de absorción sonora. Para determinar las propiedades acústicas de los nuevos materiales de absorción sonora, se utilizaron técnicas clásicas para la caracterización de materiales: el coeficiente de absorción sonora en incidencia normal y la resistencia al flujo de aire basada en el trabajo de Ingard&Dear. Se presenta un análisis comparativo entre la absorción sonora de tejidos de algodón con la misma densidad de hilo y diferente concentración de microcápsulas y diferentes densidades de hilo con el mismo porcentaje de dopaje. Los resultados muestran que la concentración de microcápsulas en correlación con la densidad de hilo tiene una influencia significativa en el coeficiente de absorción sonora.[EN] The development of new textile fabrics with microcapsules deposited on their fibers is on the rise within the textile industry. The aim of this study is focused on analyzing the influence of doping different cotton textile fabrics with microcapsules on the sound absorption coefficient. In order to determine the acoustic properties of the new sound absorbing materials, classical techniques for materials characterization were used: the sound absorption coefficient at normal incidence and the airflow resistance based on the Ingard&Dear work. A comparative analysis between the acoustic absorption of cotton fabrics with the same yarn density and different concentration of microcapsules and different yarn densities with the same doping percentage is presented. Results show that the concentration of microcapsules in correlation with the yarn density has a significant influence in the sound absorption coefficient.Authors acknowledge the support of the Ministry of Economy and Innovation (MINECO) and European Union FEDER through project FIS2015-65998-C2-2 and by projects AICO/2016/060 and ACIF/2017/073 by Regional Ministry of Education, Culture and Sport of the Generalitat Valenciana and with the support of European Structural Investment Funds (ESIF-European Union).Atiénzar-Navarro, R.; Bonet-Aracil, M.; Gisbert Paya, J.; Rey Tormos, RMD.; Picó Vila, R. (2019). Sound absorption of doped cotton textile fabrics with microcapsules. Revista de Acústica. 50(3-4):13-21. http://hdl.handle.net/10251/159990S1321503-

Sound Absorption Properties of Perforated Recycled Polyurethane Foams Reinforced with Woven Fabric

[EN] The acoustic properties of recycled polyurethane foams are well known. Such foams are used as a part of acoustic solutions in different fields such as building or transport. This paper aims to seek improvements in the sound absorption of these recycled foams when they are combined with fabrics. For this aim, foams have been drilled with cylindrical perforations, and also combined with different fabrics. The effect on the sound absorption is evaluated based on the following key parameters: perforation rate (5% and 20%), aperture size (4 mm and 6 mm), and a complete perforation depth. Experimental measurements were performed by using an impedance tube for the characterization of its acoustic behavior. Sound absorption of perforated samples is also studied¿numerically by finite element simulations, where the viscothermal losses were considered; and analytically by using models for the perforated foam and the fabric. Two textile fabrics were used in combination with perforated polyurethane samples. Results evidence a modification of the sound absorption at mid frequencies employing fabrics that have a membrane-type acoustic response.This research was financially supported by the Ministry of Economy and Innovation (MINECO) and the European Union FEDER through project FIS2015-65998-C2-2 and by projects AICO/2016/060 and ACIF/2017/073 by Regional Ministry of Education, Culture and Sport of the Generalitat Valenciana and with the support of European Structural Investment Funds (ESIF-European Union).Atiénzar-Navarro, R.; Rey Tormos, RMD.; Alba, J.; Sánchez Morcillo, VJ.; Picó Vila, R. (2020). Sound Absorption Properties of Perforated Recycled Polyurethane Foams Reinforced with Woven Fabric. Polymers. 12(2):1-18. https://doi.org/10.3390/polym12020401S118122Hamernik, R. P., & Ahroon, W. A. (1998). Interrupted noise exposures: Threshold shift dynamics and permanent effects. 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