An impedance tube submerged in a liquid for the low-frequency transmission-loss measurement of a porous material

Oblak, Miša; Pirnat, Miha; Boltežar, Miha

doi:10.1016/j.apacoust.2018.04.014

Cited by 18 publications

(9 citation statements)

References 25 publications

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“…The latter represents the higher-frequency branch of the waterborne acoustic waves that has found widespread use in medical applications. One reason for this state of affairs is the difficulty of experimental measurements, owing to the large wavelength involved and the required large impedance mismatch of the solid material for a water impedance tube (11,12). As a result, considerable studies on underwater absorption are only limited to theoretical analyses and numerical calculations (13)(14)(15)(16)(17)(18)(19)(20)(21)(22), whose idealized assumptions may not hold in practical scenarios, while almost all the existing experimental works (23)(24)(25)(26)(27)(28)(29)(30), measured in the water impedance tube, are based on small samples, which may not reflect the true performance in complex environments (31).…”

Section: Introductionmentioning

confidence: 99%

Underwater metamaterial absorber with impedance-matched composite

Gao

Tinel

et al. 2022

Sci. Adv.

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By using a structured tungsten-polyurethane composite that is impedance matched to water while simultaneously having a much slower longitudinal sound speed, we have theoretically designed and experimentally realized an underwater acoustic absorber exhibiting high absorption from 4 to 20 kHz, measured in a 5.6 m by 3.6 m water pool with the time-domain approach. The broadband functionality is achieved by optimally engineering the distribution of the Fabry-Perot resonances, based on an integration scheme, to attain impedance matching over a broad frequency range. The average thickness of the integrated absorber, 8.9 mm, is in the deep subwavelength regime (~λ/42 at 4 kHz) and close to the causal minimum thickness of 8.2 mm that is evaluated from the simulated absorption spectrum. The structured composite represents a new type of acoustic metamaterials that has high acoustic energy density and promises broad underwater applications.

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Section: Introductionmentioning

confidence: 99%

Underwater metamaterial absorber with impedance-matched composite

Gao

Tinel

et al. 2022

Sci. Adv.

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“…The tested sound frequencies in [ 19 ] ranged from 500 Hz to 2 kHz. On the basis of the ASTM E2611 standard [ 20 ], Oblak et al [ 21 ] developed a four-microphone impedance tube for measuring the sound reflection and transmission of porous material in liquids in a low-frequency range. This device was used to obtain the transmission loss of low-frequency sounds (100–500 Hz) passing through metal-foam samples.…”

Section: Introductionmentioning

confidence: 99%

“…Wilson et al [ 8 ] revealed that the 3PCM considerably improves the repeatability and accuracy of measurements in a WFIT; however, this method has not been widely employed for calibrating WFITs [ 14 , 18 , 21 ]. Furthermore, a pressurized WFIT is required to determine the behavior of sound-absorbing materials at various water depths; however, few studies have investigated the repeatability of measurements conducted using a pressurized WFIT.…”

Section: Introductionmentioning

confidence: 99%

Development and Applications of a Pressurized Water-Filled Impedance Tube

Shen

Huang

Liu

2022

Sensors

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In this study, a pressurized, water-filled impedance tube (WFIT) was developed to measure the reflection coefficients of sound-absorbing materials under various hydrostatic pressures. The developed WFIT was calibrated using a two-microphone, three-parameter calibration method (3PCM). The accuracy and repeatability of the measured reflection coefficients for the water–air interface in the WFIT were determined by comparing these coefficients with corresponding theoretical reflection coefficients. The WFIT was then used to measure the acoustic reflection coefficient of a porous rubber specimen on three dates, and the corresponding measurement results exhibited satisfactory repeatability. The aforementioned impedance tube was also used to measure the reflection coefficient of a porous rubber specimen under a hydrostatic pressure of 4 Patm three times on the same day, and one time each on three days, using the same experimental setup and measurement procedure. The results obtained in the aforementioned tests also exhibited satisfactory repeatability. Finally, the WFIT was used to measure the reflection coefficients of porous rubber specimens with various thicknesses under different hydrostatic pressures. The results of this study indicate that the developed WFIT calibrated with the 3PCM can achieve suitable repeatability in the measurement of the reflection coefficients of sound-absorbing materials under various hydrostatic pressures.

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“…The use of the impedance tube is not only limited to measure the acoustic parameter of porous material but also used in variety of applications such as fluid and soil TL measurements. [37][38][39] In this paper, the theory underlying the transfer matrix approach is described first, then followed by a description of the experimental setup using impedance tube. Various results, including the normal incidence TL are presented for an acoustic insulation of variable MF thickness with comb/ carbon sandwich panel both numerically and experimentally.…”

Section: Introductionmentioning

confidence: 99%

Estimation of acoustic transmission loss for carbon honey comb panel with melamine foam

Zai

Sami

Waseem

et al. 2022

Noise & Vibration Worldwide

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In this paper, the acoustic noise reduction of aluminum honeycomb/carbon face sheet sandwich panel with Melamine Foam (MF) lining of variable thicknesses (25 mm & 50 mm) is numerically estimated and then experimentally verified using impedance tube based on transfer matrix method. The presence of carbon face sheets and MF lining can have a significant impact on the Transmission Loss (TL). The impedance tube can measure the TL for frequency range of 64 Hz–6.2 kHz. A conventional, two-microphone impedance tube, is connected to a sample holder downstream of the first microphone pair and a section downstream of the sample holder that accommodates a second pair of microphones. The Finite Element Analysis and experimental results are compared and found in good agreements. The TL levels for each layer of material is estimated prior to have TL for combined structure. Furthermore, the optimized insulation foam thickness of 50 mm is obtained based on required acoustic parameters.

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An impedance tube submerged in a liquid for the low-frequency transmission-loss measurement of a porous material

Cited by 18 publications

References 25 publications

Underwater metamaterial absorber with impedance-matched composite

Underwater metamaterial absorber with impedance-matched composite

Development and Applications of a Pressurized Water-Filled Impedance Tube

Estimation of acoustic transmission loss for carbon honey comb panel with melamine foam

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