Fast mean and variance computation of the diffuse sound transmission through finite-sized thick and layered wall and floor systems

This paper concerns the measurement and prediction of rainfall noise with a particular focus on measurements made using the method described in the ISO rainfall noise standard. Rainfall noise is generated by rain impacting on a surface which excites the surface producing noise. Here, several different models for the force produced by a water droplet impacting on a flat inclined surface are presented. These models are designed for the nominal intense and heavy raindrops described in the ISO standard and are validated against experimental measurements. The best-performed models have been incorporated into theoretical methods for predicting the noise produced by rainfall on a flat inclined panel. These methods are used to produce noise level predictions for heavy rainfall on a standard reference test specimen which are compared with experimental measurements and show moderate agreement. These experiments were conducted using the test method described in the ISO standard. Several issues which we encountered implementing this test method are described and a number of suggestions are made to improve this method. Finally, the theoretical models are used to investigate the effect of different parameters on rainfall noise for the purpose of illustrating potential sources of error during testing using the ISO standard method.1 Note that table K1 in Annex K of ref. [5] gives four rainfall type classifications (moderate, intense, heavy and cloudburst). These are attributed to IEC 60721-2-2. However, these classification names and the rainfall characteristics (rainfall rate, typical drop diameter and fall velocity) do not correspond with those given in the current version of IEC 60721-2-2 (published in 2012) which lists 'heavy rain' as having a rainfall rate of < 16 mm.h -1 and 'very heavy rain' as having a rainfall rate < 50 mm.h -1 . No characteristics, other than rain intensity are associated with the different rain classifications in IEC 60721-2-2. However, it is stated that rain, in general, has a droplet size distribution typically 1 mm to 2 mm in diameter, with diameters up to 5 mm to 8 mm in thunderstorms; fall velocities are stated as being typically between 2 m.s -1 and 12 m.s -1 .

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“…For a thin, rectangular plate with pinned edges, the modal shape functions are given by (see ref. [39])…”

Section: Radiation Modelmentioning

confidence: 99%

On the measurement and prediction of rainfall noise

et al. 2021

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“…One possible reason for hybridization is to take care of limitations which could arise from a single model adaptation. For example, Decraene et al [119] combined the TMM and the hybrid finite element (FE)-SEA models to give a hybridized TMM-SEA model. In their analysis, two disadvantages of the single TMM were listed.…”

Section: Hybridization Modelsmentioning

confidence: 99%

“…This is because; a very fine mesh is required at high frequency. The limitations of TMM and FE-SEA therefore, led to the authors' [119] hybridized model. Their model enabled the computation of the mean and variance of diffused field STL and also avoided the detailed finite element modelling of the structure.…”

Section: Hybridization Modelsmentioning

confidence: 99%

Comparative Study of Sound Transmission Losses of Sandwich Composite Double Panel Walls

2020

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The increasing motivation behind the recently wide industrial applications of sandwich and composite double panel structures stems from their ability to absorb sounds more effectively. Meticulous selection of the geometrical and material constituents of both the core and panels of these structures can produce highly desirable properties. A good understanding of their vibro-acoustic response and emission index such as the sound transmission loss (STL) is, therefore, a requisite to producing optimal design. In this study, an overview of recent advances in STL of sandwich and composites double panels is presented. At first, some salient explanation of the various frequency and controlled regions are given. It then critically examines a number of parameter effects on the STL of sandwich and composite structures. Literatures on the numerical, analytical and experimental solutions of STL are systematically presented. Efficient and more reliable optimization problems that maximize the STL and minimize the objective functions capable of degrading the effectiveness of the structure to absorb sounds are also provided.

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“…One possibility, which was adopted in the present paper, is to make use of wavelet shape functions for this discretization [30]. Practical implementation details related to this approach are summarized in [31,Sec. 2.3].…”

Section: Impact Sound Radiationmentioning

confidence: 99%

Numerical prediction and experimental validation of impact sound radiation by timber joist floors

et al. 2020

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Timber joist floors are widely applied in residential buildings. The accurate prediction of the sound radiated by timber joist floors is challenging due to the interaction between the impacting mass and the floor, orthotropy of the joist and plate components, the effects of the floor size and boundary conditions, etc. In the present work, state-of-the-art approaches for the prediction of impact forces, structural vibration, and radiated sound power were combined into a prediction method for the sound pressure level in a room due to sound radiation by an impacted timber joist floor. This method was then extensively validated in a case study. The natural frequencies and mode shapes of the decoupled joists and plates were both experimentally determined and computed from finite element models, and a good agreement was found when an orthotropic material model is considered for all components. A considerable variation in material properties between nominally identical parts was also discovered. The accuracy of the floor assembly model was subsequently investigated, also by means of modal testing. It was found that a correct representation of the boundary conditions plays a key role in the accuracy of the predicted floor vibration field. Finally, the radiated sound pressure levels were measured and computed. A satisfactory agreement between measurement and computation was observed. At very low frequencies, the interaction between the floor and room modes can play an important role, and a modal room model is employed instead.

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Fast mean and variance computation of the diffuse sound transmission through finite-sized thick and layered wall and floor systems

Cited by 23 publications

References 30 publications

On the measurement and prediction of rainfall noise

On the measurement and prediction of rainfall noise

Comparative Study of Sound Transmission Losses of Sandwich Composite Double Panel Walls

Numerical prediction and experimental validation of impact sound radiation by timber joist floors

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