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111 124 12 2 ; OJS ; [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. 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)80024-9 Delany, 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)90031-9 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.112.0215 Romero-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/10.1121/1.4950708 ; [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 ...

[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/s20216148 ; S ; 1 ; 18 ; 20 ; 21

We report experimental evidences of spatial (angular) filtering of sound beams propagating through sonic crystals. We show that at specific frequencies of the incident wave the paraxial plane wave compo- nents of the beam can be efficiently transmitted through the crystal, whereas the components propagat- ing at large angles are strongly reflected or deflected (filtered out) by the crystal. The modification of the angular field distribution results in formation of sound beams of relatively high spatial quality. ; The work was financieall supported by Spanish Ministry of since and Innovation and European Union FEDER through projects FIS2011-29731-C02-01 and -02, Generalitat Valenciana through the procect GV/2011/2055 and the UPV through PAID-05-12. ; Picó Vila, R.; Pérez Arjona, I.; Sánchez Morcillo, VJ.; Staliünas, K. (2013). Evidences of spatial (angular) filtering of sound beams by sonic crystals. Applied Acoustics. 74(7):945-948. https://doi.org/10.1016/j.apacoust.2013.01.003 ; S ; 945 ; 948 ; 74 ; 7

[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. ...

[EN] Nondestructive testing of metallic objects that may contain embedded defects of different sizes is an important application in many industrial branches for quality control. Most of these techniques allow defect detection and its approximate localization, but few methods give enough information for its 3D reconstruction. Here we present a hybrid laser-transducer system that combines remote, laser-generated ultrasound excitation and noncontact ultrasonic transducer detection. This fully noncontact method allows access to scan areas on different object's faces and defect details from different angles/perspectives. This hybrid system can analyze the object's volume data and allows a 3D reconstruction image of the embedded defects. As a novelty for signal processing improvement, we use a 2D apodization window filtering technique, applied along with the synthetic aperture focusing algorithm, to remove the undesired effects due to side lobes and wide-angle reflections of propagating ultrasound waves, thus enhancing the resulting 3D image of the defect. Finally, we provide both qualitative and quantitative volumetric results that yield valuable information about defect location and size. ; The work was supported by Spanish Ministry of Economy and Innovation (MINECO) and European Union FEDER through project FIS2015-65998-C2-1 and FIS2015-65998-C2-2 and by project AICO/2016/060 by Conselleria de Educacion, Investigacion, Cultura y Deporte de la Generalitat Valenciana. 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.; Trull, J.; Delgado, M.; Picó Vila, R.; Romeral, L.; Cojocaru, C. (2019). Fully Noncontact Hybrid NDT for 3D Defect Reconstruction Using SAFT Algorithm and 2D Apodization Window. Sensors. 19(9):1-15. https://doi.org/10.3390/s19092138 ; S ; 1 ; 15 ; 19 ; 9 ; Her, S.-C., & Lin, S.-T. (2014). Non-Destructive Evaluation of Depth of Surface Cracks Using Ultrasonic Frequency ...

[EN] This work envisages a detailed study of two-dimensional defect localization and reconstruction, using laser generated ultrasound and its application as a remotely controlled non-destructive testing method. As an alternative to full ultrasonic or full optical approaches, we propose a hybrid configuration where ultrasound is generated by impact of laser pulses, while the detection is done with conventional transducers. We implement this approach for defect reconstruction in metallic elements and show that it combines advantages of both photonic and ultrasonic devices, reducing the drawbacks of both methods. We combine our experimental results with a high-resolution signal processing procedure based on the synthetic aperture focusing technique for the benefit of the final two-dimensional visualization of the defects. ; The work was supported by Spanish Ministry of Economy and Innovation (MINECO) and European Union FEDER through project FIS2015-65998-C2-1 and FIS2015-65998-C2-2 and by project AICO/2016/060 by Conselleria de Educacion, Investigacion, Cultura y Deporte de la Generalitat Valenciana. ; Selim, H.; Delgado-Prieto, M.; Trull, J.; Picó Vila, R.; Romeral, L.; Cojocaru, C. (2020). Defect reconstruction by non-destructive testing with laser induced ultrasonic detection. Ultrasonics. 101:1-8. https://doi.org/10.1016/j.ultras.2019.106000 ; S ; 1 ; 8 ; 101 ; Her, S.-C., & Lin, S.-T. (2014). Non-Destructive Evaluation of Depth of Surface Cracks Using Ultrasonic Frequency Analysis. Sensors, 14(9), 17146-17158. doi:10.3390/s140917146 ; Mi, B., Michaels, J. E., & Michaels, T. E. (2006). An ultrasonic method for dynamic monitoring of fatigue crack initiation and growth. The Journal of the Acoustical Society of America, 119(1), 74-85. doi:10.1121/1.2139647 ; Ham, S., Song, H., Oelze, M. L., & Popovics, J. S. (2017). A contactless ultrasonic surface wave approach to characterize distributed cracking damage in concrete. Ultrasonics, 75, 46-57. doi:10.1016/j.ultras.2016.11.003 ; Amjad, U., Yadav, S. K., ...

12 18 50 ; S ; 1 y 2 ; [EN] The aim of this study is to evaluate new sound absorbing materials from the textile engineering. For the characterization of the acoustic behavior of the textile fabrics, the Kundt tube is used: on the one hand, a campaign of sound absorption coefficient measurements are made at normal incidence; on the other hand, flow resistance measurements are made based on Ingard & Dear work. A comparative analysis is presented between the acoustic absorption of non-doped fabrics with the same doped with antimicrobial microcapsules. In addition, a plenum is used in order to improve the acoustic absorption of these fabrics ; [ES] El presente estudio tiene como objetivo poder evaluar nuevos materiales absorbentes de sonido provenientes de la ingeniería textil. Para la caracterización del comportamiento acústico de los tejidos textiles se hace uso del tubo de Kundt: por una parte, se hace una campaña de mediciones de coeficiente de absorción sonora a incidencia normal; por otra, se realizan mediciones de resistencia al flujo basado en el trabajo de Ingard&Dear. Se presenta un análisis comparativo entre la absorción acústica de las telas no dopadas, con las mismas, dopadas con microcápsulas antimicrobianas. Además, se hace uso de un plenum con objeto de mejorar la absorción acústica de estos tejidos. 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. Atiénzar-Navarro, R.; Picó Vila, R.; Rey Tormos, RMD.; Gisbert Paya, J. (2019). Absorción acústica de nuevos tejidos textiles. Revista de Acústica. 50(1 y 2):12-18. http://hdl.handle.net/10251/138039

This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. The following article appeared in Applied Physics Letters 107, 204103 (2015); doi:10.1063/1.4935917 and may be found at http://dx.doi.org/10.1063/1.4935917. ; We report the nonlinear focusing of ultrasonic waves by an axisymmetric diffraction grating immersed in water. In the linear regime, the system presents high focal gain (32 dB), with a narrow beam-width and intense side lobes as it is common in focusing by Fresnel-like lenses. Activating the nonlinearity of the host medium by using high amplitude incident waves, the focusing properties of the lens dramatically change. Theoretical predictions show that the focal gain of the system extraordinary increases in the strongly nonlinear regime (Mach number of 6.1 x 10(-4)). Particularly, the harmonic generation is locally activated at the focal spot, and the second harmonic beam is characterized by strongly reduced side-lobes and an excellent beam profile as experiments show in agreement with theory. The results can motivate applications in medical therapy or second harmonic imaging. (c) 2015 AIP Publishing LLC. ; The work was supported by Spanish Ministry of Science and Innovation and European Union FEDER through Projects FIS2011-29734-C02-01 and -02, MTM2012-36740c02-02, and PAID 2012/253. ; Jimenez, N.; Romero García, V.; Picó Vila, R.; García-Raffi, LM.; Staliünas, K. (2015). Nonlinear focusing of ultrasonic waves by an axisymmetric diffraction grating embedded in water. Applied Physics Letters. 107(20). doi:10.1063/1.4935917 ; S ; 204103 ; 107 ; 20 ; Farnow, S. A., & Auld, B. A. (1974). Acoustic Fresnel zone plate transducers. Applied Physics Letters, 25(12), 681-682. doi:10.1063/1.1655359 ; Sleva, M. Z., Hunt, W. D., & Briggs, R. D. (1994). Focusing performance of epoxy‐ and air‐backed polyvinylidene fluoride Fresnel zone plates. The Journal of the Acoustical Society of America, 96(3), 1627-1633. doi:10.1121/1.410242 ; Wang, ...

543 554 17 5 ; Senia ; The propagation of intense acoustic waves in a one-dimensional phononic crystal is studied. The medium consists in a structured fluid, formed by a periodic array of fluid layers with alternating linear acoustic properties and quadratic nonlinearity coefficient. The spacing between layers is of the order of the wavelength, therefore Bragg effects such as band gaps appear. We show that the interplay between strong dispersion and nonlinearity leads to new scenarios of wave propagation. The classical waveform distortion process typical of intense acoustic waves in homogeneous media can be strongly altered when nonlinearly generated harmonics lie inside or close to band gaps. This allows the possibility of engineer a medium in order to get a particular waveform. Examples of this include the design of media with effective (e.g., cubic) nonlinearities, or extremely linear media (where distortion can be canceled). The presented ideas open a way towards the control of acoustic wave propagation in nonlinear regime. Work supported by Spanish Ministry of Economy and Innovation and European Union FEDER through projects FIS2011-29731-C02-02 and MTM2012-36740-C02-02. AM and LMGR acknowledge Generalitat Valenciana under grants Santiago Grisolia program (grant 2012/029) and BEST2015/279 respectively. RP and VJSM acknowledge the Spanish Ministry of Economy and Innovation under grants CAS14/00232 and PRX14/00705 respectively. Jimenez, N.; Mehrem, A.; Picó Vila, R.; García-Raffi, LM.; Sánchez Morcillo, VJ. (2016). Nonlinear propagation and control of acoustic waves in phononic superlattices. Comptes Rendus Physique. 17(5):543-554. doi:10.1016/j.crhy.2016.02.004

The propagation of intense acoustic waves in a one-dimensional phononic crystal is studied. The medium consists in a structured fluid, formed by a periodic array of fluid layers with alternating linear acoustic properties and quadratic nonlinearity coefficient. The spacing between layers is of the order of the wavelength, therefore Bragg effects such as band gaps appear. We show that the interplay between strong dispersion and nonlinearity leads to new scenarios of wave propagation. The classical waveform distortion process typical of intense acoustic waves in homogeneous media can be strongly altered when nonlinearly generated harmonics lie inside or close to band gaps. This allows the possibility of engineer a medium in order to get a particular waveform. Examples of this include the design of media with effective (e.g., cubic) nonlinearities, or extremely linear media (where distortion can be canceled). The presented ideas open a way towards the control of acoustic wave propagation in nonlinear regime. ; Work supported by Spanish Ministry of Economy and Innovation and European Union FEDER through projects FIS2011-29731-C02-02 and MTM2012-36740-C02-02. AM and LMGR acknowledge Generalitat Valenciana under grants Santiago Grisolia program (grant 2012/029) and BEST2015/279 respectively. RP and VJSM acknowledge the Spanish Ministry of Economy and Innovation under grants CAS14/00232 and PRX14/00705 respectively. ; Jimenez, N.; Mehrem, A.; Picó Vila, R.; García-Raffi, LM.; Sánchez Morcillo, VJ. (2016). Nonlinear propagation and control of acoustic waves in phononic superlattices. Comptes Rendus Physique. 17(5):543-554. https://doi.org/10.1016/j.crhy.2016.02.004 ; S ; 543 ; 554 ; 17 ; 5

We propose and experimentally demonstrate a mechanism of sound wave concentration based on soft reflections in chirped sonic crystals. The reported controlled field enhancement occurs at around particular (bright) planes in the crystal and is related to a progressive slowing down of the sound wave as it propagates along the material. At these bright planes, a substantial concentration of the energy (with a local increase up to 20 times) was obtained for a linear chirp and for frequencies around the first band gap. A simple couple mode theory is proposed that interprets and estimates the observed effects. Wave concentration energy can be applied to increase the efficiency of detectors and absorbers. ; The work was supported by Spanish Ministry of Science and Innovation and European Union FEDER through projects FIS2011-29734-C02-01 and -02 and GVA/2011/055. V. R.-G. is grateful for the support of post-doctoral contracts of the UPV CEI-01-11. K. S. acknowledges the grant of UPV PAID-02-01. We acknowledge the CTFAMA and the Sonic Crystal Technologies Research Group at UPV for the use of the anechoic chamber and the 3DReAMS, respectively. ; Romero García, V.; Picó Vila, R.; Cebrecos Ruiz, A.; Sánchez Morcillo, VJ.; Staliünas, K. (2013). Enhancement of sound in chirped sonic crystals. Applied Physics Letters. 102(919):1-3. https://doi.org/10.1063/1.4793575 ; S ; 1 ; 3 ; 102 ; 919 ; Kushwaha, M. S., Halevi, P., Dobrzynski, L., & Djafari-Rouhani, B. (1993). Acoustic band structure of periodic elastic composites. Physical Review Letters, 71(13), 2022-2025. doi:10.1103/physrevlett.71.2022 ; Martínez-Sala, R., Sancho, J., Sánchez, J. V., Gómez, V., Llinares, J., & Meseguer, F. (1995). Sound attenuation by sculpture. Nature, 378(6554), 241-241. doi:10.1038/378241a0 ; Zhang, X., & Liu, Z. (2004). Negative refraction of acoustic waves in two-dimensional phononic crystals. Applied Physics Letters, 85(2), 341-343. doi:10.1063/1.1772854 ; Lu, M.-H., Zhang, C., Feng, L., Zhao, J., Chen, Y.-F., Mao, Y.-W., … Ming, ...

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 ...

[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/polym12020401 ; S ; 1 ; 18 ; 12 ; 2 ; Hamernik, R. P., & Ahroon, W. A. (1998). Interrupted noise exposures: Threshold shift dynamics and permanent effects. The Journal of the Acoustical Society of America, 103(6), 3478-3488. doi:10.1121/1.423056 ; Ramis, J., Alba, J., Del ...

[EN] The use of microcapsules is increasing in the textile industry and play an important role in the field of acoustical porous materials in order to adopt solutions for the control of noise. In this work, we present an experimental study of the acoustic effect of woven textile fabrics doped with microcapsules by using the padding technique. For this purpose, measurements with the fabric backed by an air-cavity or by a rigid wall in the impedance tube have been done. A comparative analysis of acoustic effect by using cotton fabrics with the same yarn density but different doping percentage is presented. We have investigated the influence of the sound damping effect of doping six different textile woven fabrics with the same concentration of microcapsules. The results show that the variation on the sound absorption coefficient of doped woven fabrics depends on the type of fabric, the concentration of microcapsules and the experimental setup. ; 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. (2020). Sound absorption of textile fabrics doped with microcapsules. Applied Acoustics. 164:1-9. https://doi.org/10.1016/j.apacoust.2020.107285 ; S ; 1 ; 9 ; 164 ; Berglund B, Lindvall T, Schwela DH. World Health Organization. Guidelines for community noise. Geneva, Switzerland, WHO; 1999. Available online: URL: http://www.euro.who.int/en/health-topics/environment-and-health/noise (accessed on 19 September 2019). ; Alexandre A, Barde J-P. Organization for Economic Cooperation and Development. Fighting Noise in 1990s. Eds. OECD Publications (Paris, France); 1991. ; Environmental noise. Available online: URL: ...

[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 ...