Examinando por Materia "Acoustic characterization"

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  • Publicación
    Acceso abierto
    Aplicación del método de medición de pérdida por transmisión de acuerdo a la norma ASTM E2611-09 incluyendo un quinto micrófono de medición como referencia para estimar parámetros acústicos como la pérdida por transmisión y los coeficientes de absorción y reflexión
    (2017) Gómez Salazar, Juan Camilo; Ruiz Sánchez, Santiago
    Different materials produced in the national industry for acoustic design and noise control are implemented in Colombia. Those materials behavior and their interactions with sound waves should be known to the well development of this project. Therefore, this paper intends to apply the method established in the standard ASTM E2611-09 with the objective of presenting measurements to obtain acoustic parameters of the materials as: transmission loss, absorption and reflection coefficients. Different tests were performed on the transmission tube system, making a modification that was based on the implementation of a fifth measurement microphone in its initial stage. Audio samples were obtained to be processed in the algorithm that allowed to characterize the different materials. Besides, variations were made in the assembly, and it was found that those materials are sensitive to changes in the variables present in the system. Additionally, the design of a measurement protocol was carried out in order to maintain a stability in methodology and results. The transmission loss values obtained were compared with the project that designed the system. It made possible to find that modifying the system allows getting results that are close to the theoretical curve and for this acoustic property it gives an improvement in the coherence between the signals. Based on the compared and validated values, the other acoustic parameters were obtained in which the absorption coefficient was compared with the materials data already characterized. Finally, it was concluded that the method achieves different acoustic parameters, but does not correctly and completely describe the behavior of all properties such as the absorption coefficient. In the same way, it was established that the method is a possible alternative for the acoustic characterization of materials.
  • Publicación
    Acceso abierto
    Diseño de una metodología alternativa que permita la caracterización de la radiación de una fuente electroacústica mediante el uso de una sonda P-U.
    (2017) Luján López, Luis Fernando; Estrada Duarte, Sergio Andrés; Molina Jaramillo, Alejandro
    Through the study of the standards for the determination of the sound intensity and the traditional measurement protocols to obtain the descriptors of radiation of electroacoustic sources an in situ methodology was designed that allows to estimate, for a Genelec 1032A loudspeaker, the vectorial field of intensity normal to measuring surface using the PU sensor and the Microflown´s Sound Power software. We sought to estimate a scalar and a vector unit, pressure and particle velocity respectively. Through these it was possible to calculate the measured intensity of the under study loudspeaker and thus obtain a representation of the vector field of intensity, a three-dimensional graph of its radiation. It is also understood that the measurements for pressure estimation must be performed under free field conditions, because this variable is affected by the reflections of the measurement environment due it is not of the vectorial type, for which it is not necessary to consider these contributions. An algorithm was developed for the processing of the data, so that the results could be projected on each one of the measurement positions by frequencies of third of octave. The reproducibility of the method was also evaluated by measurements in different acoustic environments. In a site with acoustic treatment the measurement distance is greater than in an enclosure without treatment due to the variation of the near field. In spite of this, it was possible to obtain satisfactory results in both places keeping the same configuration in the measurement elements.