Evaluation of moving-coil loudspeaker and passive radiator parameters using normal-incidence sound transmission measurements: Theoretical developments

A new method for determining the index of refraction from normal incidence reflection and transmission measurements has been developed. Several other methods are reviewed to explain why a new method is needed. The author's method used a thickness variational approach. For an accurate determination of n and k, the method requires normal incidence reflection and transmission measurements over a fairly broad spectral range for at least two different film thicknesses. These requirements are unavoidable for normal incidence methods.

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Transducer beam diffraction effects in sound transmission near leaky Lamb modes in elastic plates at normal incidence

2015 IEEE International Ultrasonics Symposium (IUS) ◽

10.1109/ultsym.2015.0021 ◽

2015 ◽

Cited By ~ 2

Author(s):

Magne Aanes ◽

Kjetil Daae Lohne ◽

Per Lunde ◽

Magne Vestrheim

Keyword(s):

Sound Transmission ◽

Normal Incidence ◽

Elastic Plates ◽

Diffraction Effects ◽

Beam Diffraction

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Sound transmission measurements through porous screens

The Journal of the Acoustical Society of America ◽

10.1121/1.4950307 ◽

2016 ◽

Vol 139 (4) ◽

pp. 2119-2119

Author(s):

Sarah M. Young ◽

Brian E. Anderson ◽

Nicholas B. Morrill ◽

Robert C. Davis ◽

Richard R. Vanfleet

Keyword(s):

Sound Transmission ◽

Transmission Measurements

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An improved approach for normal-incidence sound transmission loss measurement using a four-microphone impedance tube

Journal of Vibration and Control ◽

10.1177/1077546320926905 ◽

2020 ◽

pp. 107754632092690

Author(s):

Zechao Li ◽

Sizhong Chen ◽

Zhicheng Wu ◽

Lin Yang

Keyword(s):

Transfer Matrix ◽

Sound Absorption ◽

Transmission Loss ◽

Sound Transmission ◽

Normal Incidence ◽

Sound Insulation ◽

Sound Transmission Loss ◽

The Common ◽

Wavefield Decomposition ◽

Insulation Performance

The main aim of this study is to introduce an improved method for determining the sound properties of acoustic materials which is more precise than the common wavefield decomposition method and simpler than the common transfer matrix method. In the first part of the article, a group of formulae for calculating sound transmission loss is represented by combining the wavefield decomposition and transfer matrix methods. Subsequently, a formula for calculating sound absorption coefficients is derived from these formulae by definition. Furthermore, the present formulae are validated by comparing the experimental results achieved with the present formulae and those results obtained by other methods recorded in published articles. Eventually, it is demonstrated that the method can accurately measure the sound insulation performance of materials and the sound absorption properties of limp and lightweight materials.

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A hybrid method of predicting the acoustical properties of multi-layered materials

Journal of Vibration and Control ◽

10.1177/10775463211038120 ◽

2021 ◽

pp. 107754632110381

Author(s):

Zechao Li ◽

Lin Yang ◽

Hongbin Ren ◽

Sizhong Chen ◽

Zheng Liu ◽

...

Keyword(s):

Noise Control ◽

Transmission Loss ◽

Hybrid Approach ◽

Sound Transmission ◽

Normal Incidence ◽

Layered Materials ◽

Acoustical Properties ◽

Transmission And Reflection Coefficients ◽

Standing Wave Tube ◽

Laminated Materials

Many numerical and measuring approaches are widely used in predicting and analysing the acoustic performances of laminated materials for noise control applications. However, numerical methods generally require a set of non-acoustic parameters, and the measuring methods are not available for exceedingly thick materials. The main aim of this article is to address a hybrid approach of evaluating the normal incidence sound transmission loss and absorption coefficients of multi-layered materials. This method is performed with some special parameters that contain the sound transmission and reflection coefficients of each sub-layer of a multi-layer specimen and can be measured by a standing wave tube system. The accuracy and feasibility of the present method are validated by the experimental and numerical comparisons between different methods and samples. Moreover, this present approach can be applied as a numerical tool of estimating the acoustical behaviours of multi-layered structures in noise control treatments, such as automotive, building and aerospace industries.

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