Air impedance‐tube technique for measuring the acoustic properties of wet sediment samples

1974 ◽  
Vol 56 (S1) ◽  
pp. S51-S51
Author(s):  
F. D. Martin
Keyword(s):  
Acoustic Properties ◽  
Impedance Tube ◽  
Sediment Samples

scholarly journals Evaluation of the acoustic and non-acoustic properties of sound absorbing materials using a three-microphone impedance tube

2010 ◽  
Vol 71 (6) ◽  
pp. 506-509 ◽  
Author(s):  
Olivier Doutres ◽  
Yacoubou Salissou ◽  
Noureddine Atalla ◽  
Raymond Panneton
Keyword(s):  
Acoustic Properties ◽  
Impedance Tube ◽  
Absorbing Materials

scholarly journals Identification of uncertainty levels of acoustic properties of biocomposites under different mounting conditions in impedance tube tests

2021 ◽  
Vol 69 (5) ◽  
pp. 392-400
Author(s):  
Hasan Koruk ◽  
Yusuf Saygili ◽  
Garip Genc ◽  
Kenan Y. Sanliturk
Keyword(s):  
Sound Absorption ◽  
Transmission Loss ◽  
Acoustic Properties ◽  
Petroleum Jelly ◽  
Impedance Tube ◽  
Hard Materials ◽  
Inner Diameter ◽  
Acoustic Properties Of Materials ◽  
Impedance Tube Method ◽  
Textured Materials

Impedance tube method is widely used to measure acoustic properties of materials. Although this method yields reliable acoustic properties for soft textured materials, uncertainty levels of measured acoustic properties for hard materials, including biocomposites, can be quite large, mainly due to uncertain mounting conditions. Here, the effects of mounting conditions on the acoustic properties of biocomposites in an impedance tube are investigated. First, nominally identical biocomposite samples with a diameter equal to the inner diameter of impedance tube are manufactured and their acoustic properties are determined. As hard materials practically cause fitting problems in the impedance tube, the diameters of samples are reduced, as in practice, by small amounts and acoustic properties of modified samples are determined. Furthermore, in order to match the diameters of samples to the inner diameter of impedance tube, different materials such as tape, petroleum jelly and cotton are applied around samples to close the air gap between the samples and the tube's inner wall. All the results are compared, and the uncertainty levels caused by different mounting conditions on the acoustic properties of biocomposites are identified. The results show that the transmission loss (TL) measurements are dramatically affected by the mounting conditions while the sound absorption conditions are less sensitive to the mounting conditions. The deviations in the measured TL levels are highest for the samples with tape and wax (10–15 dB). On the other hand, the deviations in the measured sound absorption coefficients are highest for the samples with cotton and tape (1–2%).

TEST METHOD TO DETERMINE THE ACOUSTIC PROPERTIES OF BUILDING MATERIAL BY USING MICROPHONE IMPEDANCE TUBE

Akustika ◽  
2021 ◽  
pp. 36-42
Author(s):  
Sourabh Dogra ◽  
Arpan Gupta
Keyword(s):  
Reflection Coefficient ◽  
Absorption Coefficient ◽  
Virtual Instrument ◽  
Building Materials ◽  
Low Cost ◽  
Test Method ◽  
Wood Fibre ◽  
Acoustic Properties ◽  
Impedance Tube ◽  
Acoustical Properties

The paper discusses a simple and low-cost method to design four microphone impedance tube of measuring the acoustic properties of building materials. The acoustic properties of the material are defined by the reflection coefficient, absorption coefficient, and transmission coefficient. The experimental setup follows the ASTM-E2611 standard of four microphone impedance tube with two load boundary conditions to measure these coefficients. The setup consists of four microphones around a brass tube with the speaker at one end and termination at the other. Raw data from the four microphones is obtained through a Virtual Instrument (VI) program developed in LabView. The novelty in the design is the tapered connection between the two pipes connected via the sample holder. The mathematical equation involved in estimating acoustical properties is solved in MATLAB 2019a. The reflection and absorption coefficient data of ephony fibbrette of 15 mm thickness are compared with the data provided by an accredited laboratory. The experimental results of the in-house designed impedance tube are in good agreement with the lab results. This material is used in the auditorium, theatres for hearing comfort. Further, two new samples of ephony fibbrette along with wood fibre cement and damper has been analysed. It has been found that adding a layer of wood fibre results in an increase in the absorption coefficient whereas the addition of the damper results in an increase in the reflection coefficient.

scholarly journals Development of Impedance Tube to Measure Sound Absorption Coefficient

2019 ◽  
Vol 8 (6) ◽  
pp. 3218-3222
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Transmission Loss ◽  
Acoustic Property ◽  
Small Sample ◽  
Textile Material ◽  
Acoustic Properties ◽  
Sound Absorption Coefficient ◽  
Impedance Tube ◽  
Significant Difference

An acoustic property of textile material can be measured using an impedance tube, is the most popular technique to measure normal sound absorption and transmission loss. This method consuming less time and a very small sample is required to assess the acoustic properties of the materials. Unfortunately, the cost of the impedance tube and software used for measurement is very high. This paper gives information about how to develop a cost-effective impedance tube suitable for researchers. The design, development, and fabrication of the impedance tube suitable for different frequencies with technical details are present here. Information related to some software which can be used to measure sound absorption coefficient also provided. To validate the testing results obtained from custom-build impedance tube, same samples were tested on commercially available impedance tube at PSG College, Coimbatore. It was observed that both the instruments provide almost same results, no statistically significant difference found in results. Base on the results design of customized impedance tube recommends to student and researcher interested in measuring acoustic properties of textile material

Automotive Noise Insulation Composite Panel Using Natural Fibres with Different Perforation Areas

2012 ◽  
Vol 165 ◽  
pp. 63-67 ◽  
Author(s):  
Zulkifli R. ◽  
T.K. Thye ◽  
Mohd Faizal Bin Mat Tahir ◽  
Ahmad Rasdan Ismail ◽  
Mohd Jailani Mohd Nor
Keyword(s):  
Absorption Coefficient ◽  
Volume Fraction ◽  
Fibre Volume Fraction ◽  
Fibre Volume ◽  
Acoustic Properties ◽  
Composite Panel ◽  
Impedance Tube ◽  
Coir Fibre ◽  
Noise Absorption ◽  
Kenaf Fibre

This research was carried out to study the acoustic properties of natural organic fibres; kenaf and coir fibres using impedance tube method. Kenaf fibre was used as noise absorber filler in an insulation panel while the coir fibre as reinforcement in the perforated composite panel. The perforated panel was made from coir fibre/polyester composites with coir fibre volume fraction of 10%, 20% and 30%. The perforation area of the perforated panel was also varied at 10%, 20% and 30%. During the processing stage, the kenaf fibre sheet has been treated with PVA and cut into 100 mm and 30 mm diameter sample for low and high frequency test. The density of the coir fibre is determined to be 32.2 g/cm3 while the density of the kenaf fibre is 42.6 g/cm3. The tests were carried out using impedance tube at acoustic lab, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia using ISO 10534-2 standard for noise absorption coefficients to determine their noise absorption coefficient. The results obtained show that the optimum noise absorption coefficient index for kenaf fibre is 0.8 with 10% fibre volume fraction of coir fibre/polyester perforated composites panel at 10% perforation areas.

THEORY OF A RESONANCE METHOD TO MEASURE THE ACOUSTIC PROPERTIES OF SEDIMENTS

Geophysics ◽  
1956 ◽  
Vol 21 (2) ◽  
pp. 299-304 ◽  
Author(s):  
W. J. Toulis
Keyword(s):  
Finite Thickness ◽  
Resonance Method ◽  
Acoustic Properties ◽  
Velocity Of Sound ◽  
Attenuation Constant ◽  
Cylindrical Chamber ◽  
Sediment Samples ◽  
Pressure Release ◽  
Acoustic Losses

The theory of resonance for a pressure release cylindrical chamber is explored and equations are derived for determining absolute values of the velocity of sound and the attenuation constant in sediment samples. The essential measurements that need to be made are the determination of the frequencies of the lower modes of resonance and the associated sharpness of resonance. Corrections are derived also for the finite thickness and the acoustic losses in the chamber walls.

Assessment of the Acoustic Properties in Octavo Bands for Selected Polyurethane Materials

2016 ◽  
Vol 246 ◽  
pp. 7-10
Author(s):  
Tomasz Małysa ◽  
Krzysztof Nowacki ◽  
Teresa Lis
Keyword(s):  
Polyurethane Foam ◽  
Sound Absorption ◽  
Acoustic Properties ◽  
Frequency Range ◽  
Absorption Coefficients ◽  
Impedance Tube

The article presents the acoustic properties of selected polyurethane materials. The study involved a porous polyurethane foam primary and secondary, for whom assigned the value of sound absorption coefficients in the frequency range of 100 – 1250 Hz. The study was conducted in impedance tube Kundt.

Acoustic characterization of Zea Mays culm fibers (corn) and Musa X Paradisiacal (banana) stem fibers in proportion 50% - 50%.

2021 ◽  
Vol 263 (5) ◽  
pp. 1426-1434
Author(s):  
Yesika Patricia Alvarez Ruiz ◽  
José Alcides Ruiz Hernández
Keyword(s):  
Zea Mays ◽  
Absorption Coefficient ◽  
Software Tool ◽  
Computational Procedure ◽  
Sound Level ◽  
Acoustic Properties ◽  
Impedance Tube ◽  
Class 1 ◽  
Impedance Tubes ◽  
Noise Measurements

The following research arises as a proposal to the implementation of Zea Mays culm fibers and Musa X Paradisiaca stem fibers in proportion 50% - 50% for the development of a new eco-material with acoustic properties, the objective was to measure the absorption coefficient based on the international standard ISO 10534-1 Determination of the acoustic absorption coefficient and acoustic impedance in impedance tubes. Using the impedance tube to identify the minimums and maximums needed to perform the computational procedure in the MATLAB software tool, and finally obtain the sound absorption coefficients of the material. The measurement process is supported by the implementation of the impedance tube, having all its consideration and previous measures that support the veracity of the data taken through this process, in addition to the fact that background noise measurements were made in order to pass these values to ensure reliable results in the measurement, performed with a class 1 sound level meter; The fibers analyzed had a range between 0.8136 and 0.9225 absorption coefficient in the bands of 1000, 2000 and 4000 Hz, testing the effectiveness in their implementation as an acoustic barrier. Keywords: absorption, eco-material, fibers, barrier, acoustics.

Acoustic Properties of Cork Sheets

2017 ◽  
Vol 744 ◽  
pp. 66-70 ◽  
Author(s):  
Amelia Trematerra ◽  
Ilaria Lombardi
Keyword(s):  
Absorption Coefficient ◽  
Rigid Wall ◽  
Acoustic Properties ◽  
Frequency Range ◽  
Impedance Tube ◽  
Green Material ◽  
Sustainable Material ◽  
Synthetic Materials ◽  
Green Materials

Green materials can be considered as a valid alternative to traditional synthetic materials. The cork is a green material, in fact it is a sustainable material. Cork can be used to improve the acoustics inside buildings. The systems used consist of cork sheets mounted at a distance onto a rigid wall, with the thickness of the sheet being 1.5 mm. The distances from the rigid wall considered are equal to 5 cm, 10 cm and 15 cm. The absorption coefficient of the sample was measured in the frequency range from 100 Hz to 2000 Hz with an impedance tube.

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