Measuring the absorption coefficient of panels at oblique incidence by using inverse filtered MLS signals

Cobo, Pedro; Cuesta, María; Pfretzschner, Jaime; Fernández, Alejandro; Siguero, Manuel

doi:10.3397/1.2375038

Cited by 4 publications

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“…These traces have been measured at normal incidence, with the loudspeaker and the microphone 90 and 5 cm away from the center of the panel, respectively. This is the optimal loudspeaker-microphone configuration for the size of the tested panel (Cobo et al, 2006a). Time windowing removes low frequencies from the measured signals, so that this method has a lowest reliable frequency inversely related with the window length (Cobo, 2007).…”

Section: Resultsmentioning

confidence: 99%

“…Pfretzschner et al (2006) proposed an alternative methodology to construct more structurally robust MPPs, combining a thick panel with large perforations with a thinner one highly perforated. The passive absorption of such an extended absorber has already been measured, at normal incidence (Pfretzschner et al, 2006), at low angles of incidence in a free field (Cobo et al, 2006a), and in a reverberation room (Cobo et al, 2006b). The current research is concerned with the design of the active absorber as well as the hybrid passive-active absorption measurements.…”

Section: Hybrid Passive-active Absorber In Anechoic Roommentioning

confidence: 99%

“…Both the number of taps and the algorithm convergence parameter of the control and error path identification filters can be modified to optimize the cancellation at the microphones. Both passive and active absorption coefficients of such a prototype have been measured with the method outlined by Cobo et al (2006aCobo et al ( , 2007. This MLS (maximum length sequences) impulsive technique requires a loudspeaker-microphone system optimally positioned according to their relative distances to the sample (see Fig.…”

Section: Hybrid Passive-active Absorber In Anechoic Roommentioning

confidence: 99%

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Hybrid passive-active absorption of a microperforated panel in free field conditions

Cobo

Cuesta

2007

The Journal of the Acoustical Society of America

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Although hybrid passive-active absorption in impedance tubes has been widely analyzed, its study in more realistic conditions remains to be accomplished. This letter describes the practical measurement of the passive-active absorption coefficient in a free field. The passive absorber consists of a microperforated panel backed by an air cavity and a wooden panel. A multichannel active system controls the sound pressure in a reduced cell behind the absorber. Measured absorption coefficients between 200 and 400Hz account for 0.2–0.4 and 0.72–0.75, in the passive and active cases, respectively, and above 500Hz both are comparable.

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Section: Resultsmentioning

confidence: 99%

Section: Hybrid Passive-active Absorber In Anechoic Roommentioning

confidence: 99%

Section: Hybrid Passive-active Absorber In Anechoic Roommentioning

confidence: 99%

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Hybrid passive-active absorption of a microperforated panel in free field conditions

Cobo

Cuesta

2007

The Journal of the Acoustical Society of America

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“…(6.5), with the zero-phase cosinemagnitude spectrum of Eqs. (6.7) (6.8) (Cobo et al, 2006, Cobo et al, 2007.…”

Section: Loudspeaker Equalization By Inverse Filteringmentioning

confidence: 99%

Acoustic characterization of open cavities with the image source model

Montaño¹

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Primero que todo quiero agradecer de corazón a mis padres María del Socorro y Cesar Alfonso por el amor incondicional y el apoyo que siempre me han brindado. Les estoy eternamente agradecido y cada día doy gracias a la vida por tenerlos. Igualmente a mi hermana Martha y a mi hermano Jose a quienes quiero y admiro profundamente.En segundo lugar quisiera agradecer a mi director de Tesis Dr. Pedro Cobo Parra por la confianza y la paciencia depositada en mi y por abrirme las puertas de su conocimiento generosa y amablemente para así poder construir ¨sobre hombros de gigantes¨.Gracias por enseñarme a llevar a cabo el trabajo con rigor científico y con resultados claros, por darme la oportunidad y por levantarme en los momentos difíciles.Por último pero sin duda una parte fundamental en el camino de esta tesis, quiero agradecer a toda la gente maravillosa con la que compartí experiencias inolvidables; a mis compañeros de despacho Heidi, David y Cristóbal que ahora considero buenos amigos, al inigualable Shiva, a Jaime Rodríguez, a Pedrito Castro y Carlitos Sierra , a la hermosa Carmen, a Toñi , a Paco Montero, a todos los del fútbol y a los compañeros del máster. Fue una época maravillosa y nunca los olvidaré.

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Efficient modeling and experimental validation of acoustic resonances in three-dimensional rectangular open cavities

Ortiz

Plenier²,

Cobo

2013

Applied Acoustics

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Measuring the absorption coefficient of panels at oblique incidence by using inverse filtered MLS signals

Cited by 4 publications

References 0 publications

Hybrid passive-active absorption of a microperforated panel in free field conditions

Hybrid passive-active absorption of a microperforated panel in free field conditions

Acoustic characterization of open cavities with the image source model

Efficient modeling and experimental validation of acoustic resonances in three-dimensional rectangular open cavities

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