Sound Properties Research Articles

Parenting styles as predictors to female students’ sexual promiscuity in tertiary institution in delta state

This study investigated the relationship between parenting styles and female students’ sexual promiscuity in tertiary institutions in Delta State. The study was led by two research questions and two hypotheses. The study used an ex-post facto research design with a correlational technique. The population comprised all female students of tertiary institutions in Delta Central Senatorial District with a total sample of 1,566 students. Questionnaire was used as instrument of data collection. The questionnaire was validated by experts’ judgement and factor analysis, with a sound psychometric property indicating that the instrument is valid and reliable. The data obtained were analysed with the aid of regression statistics at 0.05 level of significance. The result showed a significant relationship between parenting styles and sexual promiscuity and that the relationship can be moderated by socio-economic status of parents. The study recommended amongst others that Parents should improve on their relationship with their adolescents and choose the right parenting style that will help the adolescents to abstain from risky sexual behaviour.

Decoding reveals the neural representation of perceived and imagined musical sounds.

Vividly imagining a song or a melody is a skill that many people accomplish with relatively little effort. However, we are only beginning to understand how the brain represents, holds, and manipulates these musical "thoughts." Here, we decoded perceived and imagined melodies from magnetoencephalography (MEG) brain data (N = 71) to characterize their neural representation. We found that, during perception, auditory regions represent the sensory properties of individual sounds. In contrast, a widespread network including fronto-parietal cortex, hippocampus, basal nuclei, and sensorimotor regions hold the melody as an abstract unit during both perception and imagination. Furthermore, the mental manipulation of a melody systematically changes its neural representation, reflecting volitional control of auditory images. Our work sheds light on the nature and dynamics of auditory representations, informing future research on neural decoding of auditory imagination.

Comparison of sound insulation performance between closed-cell foam and automotive carpet

In developing sound insulation materials for automobiles, multiple sound insulation and sound absorption materials are laminated to achieve high performance. Generally, steel sheets, needle felts, and carpets are used to create sound insulation properties. In a luxury car, multiple layers with sound absorption and sound insulation properties are placed on the carpet to add higher sound insulation properties, but this increases the mass of the carpet. To solve this problem, we are investigating the the potential to realize both lightweight and high sound insulation properties using closed-cell form. In this study, we experimentally evaluated the sound transmission loss of closed-cell foam by comparing it with those of carpets with the same configuration used in standard and luxury cars.Furthermore, a numerical study is conducted. As a result, the closed-cell foam obtained higher sound transmission loss than the automobile specification carpet in a wide frequency range from 400 Hz to 5000 Hz. On the other hand, the sound transmission loss decreased by the same degree for both the automotive carpets and the closed-cell foam at 250 Hz.

Applying acoustical criteria to architectural projects

The requirements for building acoustics should be integrated into the architectural project as early as the preliminary design phase.The materials, densities and thicknesses used in the manufacture of building elements vary from country to country. Therefore, in each country there are building products with different sound insulation properties resulting from the different characteristics of the building elements. We are developing a local building element database addin for a BIM programme that the architect can easily insert into the project by classifying the sound insulation properties of the building elements used in Turkey according to their thickness, density and layer properties, which are determined by calculation or measurement. In the future, we plan to integrate additional properties of the building elements, such as fire resistance, sustainability and cost information, which will facilitate the design of the building.

Multiphysical design for optimised ventilation and noise attenuation in ducts: an approach using metamaterials

Noise generation and propagation through mechanical ventilation and air conditioning (MVAC) ducts have been increasingly investigated since commercial solutions allow sensible noise attenuation while reducing the duct section. So, a commercial silencer forces the MVAC power to rise to overcome the flow resistance, increasing the noise source. For this reason, this study focuses on soundproofing ventilation ducts through acoustic metamaterials with no inner duct section decreasing. A crucial part of this study falls into the multiphysical interaction between acoustics and fluid dynamics, which is a phenomenon that may result in a challenging analytical model. In conditions of flowing motion, the wave vector has been modelled according to the Lighthill model: the component of the velocity rotor potential becomes significant, influencing the soundproofing performance due to the metamaterial placed at the edge of the inner surface of the duct. FEM analysis helped design a series of samples which then have been tested experimentally in static conditions. Once the numerical method is calibrated, further multiphysical numerical analysis are used to implement the sound insulation properties of the metamaterial-based filter through dynamic flow conditions. Guidelines for multiphysical setup for wave-based simulation are drawn, and preliminary experimental results are presented.

ETICS measurements and prediction - Verification and validation of a predictive model for the improvement of airborne sound insulation of thick external linings

The increasing demand of the reduction of carbon emissions and the consumption of energy resources due to the construction sector leads to the concept of Zero-Energy buildings. It is therefore crucial ensuring technical and engineering compatibility between future advancements in energy efficiency and sound insulation. The sound insulation requirements for residential buildings are mandatory in Italian Regulations, tested on-site after construction completion. A noteworthy challenge is the potential synergy between specifications for energy efficiency and the sound insulation properties in building materials. This paper deals with the validation of the prediction model for the improvement of airborne sound insulation due to thick external linings, particularly materials used in ETICS (External Thermal Insulation System), based on mechanical properties of involved materials. Standard ISO 9052-1 for the determination of dynamic stiffness is intended for materials used under floating floors in dwellings. However, based on the methods of this standard, it is possible to perform measurements (with both hammer and shaker) even on thick linings materials, and use the results for the implementation of computational models for the predictions of airborne sound insulation improvement, as a function of frequency, with good accuracy.

Selection of measurement positions for measuring sound reflection of noise barriers

The number of positions for the in-situ measurement of sound reflection under direct sound field conditions according to EN 1793-5 for road traffic noise reducing devices (NRDs, e.g. noise barriers) depends on the surface structure of the device under test. The surface structure and material homogeneity may be categorized as flat and non-flat as well as homogenous and inhomogeneous. Flat and homogenous NRDs are measured with one central measurement position, whereas non-flat and or inhomogeneous devices require additional measurements points to assess the overall sound reflection properties. In the current version of the standard, NRDs are considered flat, if the depth of their surface structure is below 8.5 cm. Also, they are considered homogenous if the lateral extent of each material is at least 8.5 cm. It is discussed to reduce this criterion from 8.5 cm to 1.7 cm, as research showed significant differences on devices considered as flat between measurement positions for the sound reflection index. An extensive analysis of sound reflection measurements shows the influence of the measurement position for noise barriers with structural depths below 8.5 cm. A new strategy for selecting measurement positions is proposed, which also considers the period length of the surface structure.

A basic study on sound insulation characteristics of Triply Periodic Minimal Surface by using the finite element method

Triply periodic minimal surfaces (TPMS) have garnered attention in the field of natural science. For example, these structures are observed in insect wing scales, where their intricate periodic structures create structural colors via the reflection and interference of certain wavelengths of light. The objective of this study is to utilize the acoustic analogy of such photonic properties for sound insulation. In a previous report, it was found that the bandgap of G-surface, which is one of TPMS, enabled us to insulate sound effectively at specific frequencies. Furthermore, it was suggested that sound insulation performance can be improved by compressing the structure along the incident direction while maintaining its thickness. In this paper, we focus on the P-surface, which is a typical TPMS other than the G-surface. The sound insulation properties were calculated by numerical analysis and compared with those of the G-surface. As a result, it is found that P- and G-surfaces are effective structures for different frequency bands. In addition, compression of the P-surface along the incident direction in the same manner as in the previous study improves the sound insulation performance without increasing the thickness, as well as G-surface.

Investigating the acoustic performance of sustainable composites utilizing recycled polypropylene and denim shoddy: fabrication, characterization, and theoretical Modelling

Addressing the urgent need for sustainable materials, this study investigates the development of eco-friendly composites using Recycled Polypropylene (RPP) and Denim Shoddy (DS) for sound insulation. Two configurations were fabricated through compression molding: one with only RPP and the other incorporating a DS interlayer, repurposing waste materials such as post-consumer cosmetic containers and denim textile waste. The investigation evaluated the composites' density and sound transmission loss (STL). Theoretical calculations of STL in diffuse fields across various angles assessed the composites' real-world applicability. Incorporating a DS interlayer significantly improved sound insulation properties, with the composite exhibiting a higher density of 916 kg/m³ compared to 891 kg/m³ for Neat RPP. STL measurements showed that the composite achieved approximately average STL of 39.0 dB under normal incidence and 30.8 dB in the diffuse field, compared to 37.7 dB and 30.6 dB for Neat RPP, indicating a positive correlation between increased density and enhanced sound insulation. These findings highlight the potential of using recycled and waste materials for eco-friendly, sound-insulating material. The developed materials show promising applications in highway noise barriers, generator insulation, and office cabin partitions. This research contributes to sustainable materials science by demonstrating innovative sound-insulating composites' environmental and practical benefits.

Development and analysis of Fe-doped ZnO nanoparticle-infused sisal fiber reinforced hybrid polymer composites for high-performance sound absorption and thermal insulation applications

In the current study, sisal fiber-reinforced hybrid composites have been developed by integrating a bidirectional mat with a blend of epoxy using Fe-doped ZnO (IDZO) nanoparticles at concentrations of 0.2, 0.4, 0.6, and 0.8 wt%. Hand-lay-up approach was used to create the composites. The composites were characterized through a comprehensive analysis of their density, water absorption, elasticity, thermogravimetric analysis, mechanical resistance, thermal conductivity, microhardness, and propagation of sound properties, including sound absorption coefficients and sound transmission class ratings. As filler loading increased, the bio-composite sample’s hardness increased under the density and void volume fraction values, with 0.8 wt% composite sample showing the superior micro-hardness. A positive correlation was observed between the ZnO nanoparticle weight percentage and thermal conductivity, with improve nanoparticle content leading to improved thermal performance. Composites containing 0.4 wt percent nanoparticles showed superior tensile strength (66.8–84.16 MPa), flexural strength (97.69–120.02 MPa) and flexural modulus (3.56–7.68 GPa). It has been observed that the weight percentage of IDZO filler greatly influences the sound absorption efficiency of the current composites. These findings highlight the promising potential of these novel biocomposites in advanced engineering applications, emphasizing their usefulness in demanding environments with biodegradability and high-performance thermal, mechanical, and acoustic properties. Based on the sound transmission class ratings, the sisal fiber biocomposites have been regarded as great adoptions for use as sound-absorbing materials such as wall partitions, doors, enclosures, and structural components, thermal insulation systems, and electrical insulation.

Collaborative sound design for automotive applications - the sound for electric vehicle as an emblematic use case

Within the automotive industry, the Electric Vehicle (EV) represents an incredible challenge and an extensive field of research for sound design developments and applications. In fact, conceiving the external sound of a silent and dynamic object moving in urban or rural environments meets several important constraints: functionality, usability, aesthetics, identity, and of course, sustainability. Then, the multidisciplinary nature of this topic argues for a collaborative approach, in order to co-understand the problem and co-conceive the solutions. But, whereas design has long been developing relevant research works and efficient methods for co-design, sound design still lacks references and tools for co-sound design. In a long-standing collaboration with a French car manufacturer, two recent - and still in-progress - projects have allowed to implement, adapt and test in real life a collaborative sound design framework that was previously developed in a research context, and has since been instantiated in various other applications. This framework - based on a set of tangible intermediary objects and a digital sound lexicon expliciting sound properties - will be presented. Its implementation will be detailed in a comparative approach. Its strengths and weaknesses will be developed in the light of some results obtained within both respective projects.

Utilizing polydispersity in three-dimensional random fibrous based sound absorbing materials

The distribution of fiber diameters plays a crucial role in the transport and sound absorbing properties of a three-dimensional random fibrous (3D-RF) medium. Conventionally, volume-weighted averaging of fiber diameters has been utilized as an appropriate microstructural descriptor to predict the static viscous permeability of 3D-RF media. However, the long wavelength acoustical properties of a 3D-RF medium are also sensitive to the smallest fibers, this is particularly true in the high-frequency regime. In our recent research, we demonstrated that an inverse volume-weighted averaging of fiber diameters can effectively serve as a complementary microstructural descriptor to capture the high-frequency behavior of polydisperse fibrous media. In the present work, we reexamine the identification of two representative volume elements (RVEs) which relies on the reconstruction of 3D-RF microstructures having volume-weighted and inverse-volume weighted averaged fiber diameters, respectively in the low-frequency and high frequency regimes. We investigate the implication of such a weighting procedure on the transport and sound absorbing properties of polydisperse fibrous media, highlighting their potential advantages. Furthermore, we discuss the challenges associated with this research field. Finally, we provide a brief perspective of the future directions and opportunities for advancing this area of study.

Polyetherimide copolymer film with room-temperature self-healing properties and high breakdown field strength

With the waste of resources caused by human activities, it has gradually become an increasingly prominent social problem. The development of self-healing polymers in the field of insulation has attracted widespread attention. Develop polymer matrices with efficient healing efficiency and sound insulation properties to achieve green and sustainable resource conservation. In addition, improving the dielectric properties of intrinsic self-healing matrices has been a hot topic. In this work, we developed a new PEI matrix-modified self-healing polymer substrate that provides a breakdown field strength of 240 kV/mm and self-healing properties at room temperature, this has significantly improved the dielectric properties over other previously reported self-healing polymers. In addition to the abovementioned performance, we found significant differences in thermodynamic behavior in the synthesized end-modified polymers. By dielectric characterization (LCR), the breakdown composite can be left at room temperature for 60 min, and the material can recover 80 % of the initial properties without external intervention(This is demonstrated by the fact that its DC conductivity at 60 min of autonomous healing was significantly changed from that of the freshly electrically pierced DC conductivity and remained around 5.38 × 10−11 S/cm for a longer period of time thereafter). The microscopic morphology of the modified PEI matrix was observed by scanning electron microscopy (SEM) and EDS surface elemental analysis, which further supports the existence of metal coordination structures. These findings can further deepen the thinking of self-healing dielectric composites. The work inspired by this may break the limits and take self-healing composite dielectric materials to a new height.

Investigation of kevlar application in baglama soundboard and its effects on sound properties

One of the most important problems of the baglama is the need for sound power. In order to solve the same problem in the guitar, double tops were applied and this problem was largely solved. It is thought that the application will also be a solution for the baglama. In this application, the soundboard consists of two pieces and a material called kevlar, designed in the shape of a honeycomb, is mounted between two wooden parts. Kevlar is a mounted between the soundboard, which consists of the lower cover and the upper cover in the instruments, both reducing the wooden part and creating sound chambers. It has been observed in the analyses that this structure has a positive effect on the sound in the guitar. It is thought that the use of kevlar in the baglama soundboard with the same method will have a positive effect on sound power.

A pneumatic soft acoustic metamaterial through modular design

Tunable acoustic metamaterials have excellent sound waves control and manipulation properties because of their deformations under different stimuli. Pneumatic actuation has recently attracted the attention due to its low-cost, fast in response and easy to integrate. However, due to the difficulty in fabricating soft enough scatterers and ensuring their airtightness, the experimental realization of pneumatic soft acoustic metamaterials remains a great challenge. In this paper, a pneumatic soft acoustic metamaterial is designed and its tunable band gap has been experimentally demonstrated. The designed pneumatic soft acoustic metamaterial comprises an array of soft inflatable rubber cavities in the background of air. And the scatterer in the soft acoustic metamaterials can deform by adjusting the air pressure, which can switch on or off the band gaps. The effects of scatterer shapes and orientations on the adjustable band gap are studied using numerical simulation methods. Furthermore, the modular design is introduced to ensure the flexibility of the designed soft acoustic metamaterials. And we fabricate modularized pneumatic soft acoustic metamaterials with square scatterers through the casting molding approach. The acoustic experiment results are agreement with the simulation results, which demonstrates that the band gap can be efficiently tuned when applying the air pressure. Additionally, the average transmission drops by about 20.2 dB in the maximum band gap of 3209.7–4639.7 Hz. This study provides a guide for designing and fabricating a pneumatic soft acoustic metamaterial, and confirms the feasibility and application potential of the design of acoustic devices by harnessing pneumatic actuation.

A dual-penalized approach to hypothesis testing in high-dimensional linear mediation models

The field of mediation analysis, specifically high-dimensional mediation analysis, has been arousing great interest due to its applications in genetics, economics and other areas. Mediation analysis aims to investigate how exposure variables influence outcome variable via mediators, and it is categorized into direct and indirect effects based on whether the influence is mediated. A novel hypothesis testing method, called the dual-penalized method, is proposed to test direct and indirect effects. This method offers mild conditions and sound theoretical properties. Additionally, the asymptotic distributions of the proposed estimators are established to perform hypothesis testing. Results from simulation studies demonstrate that the dual-penalized method is highly effective, especially in weak signal settings. Further more, the application of this method to the childhood trauma data set reveals a new mediator with a credible basis in biological processes.

Lenition in L2 Spanish: The Impact of Study Abroad on Phonological Acquisition.

Objective: This study investigated the degrees of lenition, or consonantal weakening, in the production of Spanish stop consonants by native English speakers during a study abroad (SA) program. Lenition is a key phonological process in Spanish, where voiced stops (/b/, /d/, /ɡ/) typically weaken to fricatives or approximants in specific phonetic environments. For L2 learners, mastering this subtle process is essential for achieving native-like pronunciation. Methods: To assess the learners' progress in acquiring lenition, we employed Phonet, a deep learning model. Unlike traditional quantitative acoustic methods that focus on measuring the physical properties of speech sounds, Phonet utilizes recurrent neural networks to predict the posterior probabilities of phonological features, particularly sonorant and continuant characteristics, which are central to the lenition process. Results: The results indicated that while learners showed progress in producing the fricative-like variants of lenition during the SA program and understood how to produce lenition in appropriate contexts, the retention of these phonological gains was not sustained after their return. Additionally, unlike native speakers, the learners never fully achieved the approximant-like realization of lenition. Conclusions: These findings underscore the need for sustained exposure and practice beyond the SA experience to ensure the long-term retention of L2 phonological patterns. While SA programs offer valuable opportunities for enhancing L2 pronunciation, they should be supplemented with ongoing support to consolidate and extend the gains achieved during the immersive experience.

Content validity of measures in early numeracy in children up to eight years: A COSMIN systematic review

Early numeracy skills are considered essential predictors for later mathematical and educational achievement. Therefore, there is a need for early numeracy measures with psychometrically sound properties. This systematic review aimed to determine the content validity of all current early numeracy measures in accordance with the COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN) framework and methodological guidelines, and was conducted and reported by following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 statement and checklist. Systematic literature searches were conducted in January 2024 in five electronic databases: CINAHL, Embase, Eric, PsycINFO, and PubMed. Eligible measures assessed numeracy, targeted children up to eight years of age, were published in English in 1995 or later, and had psychometric data on measure dimensionality. Eligible psychometric reports that were published in English described instrument development and/or content validity of included measures. The measures’ methodological quality was assessed using the COSMIN Risk of Bias checklist, after which all three aspects of content validity (i.e., relevance, comprehensiveness and comprehensibility) were evaluated. Six early numeracy measures and eleven psychometric reports were included. None of the measures could be recommended for use in clinical practice, education, or research due to a lack of high-quality evidence on content validity. However, no high-quality evidence was found to indicate insufficient content validity, therefore, all measures still have the potential to be used. Limited access to measures in the domain of early numeracy, despite having contacted both publishers and instrument developers, may have negatively impacted the completeness of the current overview of content validity of early numeracy measures. In line with the COSMIN guidelines, after the initial evaluation of content validity, future studies should evaluate the remaining psychometric properties of the included measures to identify the most robust measures in terms of validity, reliability, and responsiveness.

3D Cementitious composites printing with pretreated recycled crumb rubber: mechanical and acoustic insulation properties

ABSTRACT Cementitious materials incorporating recycled crumb rubber have become a common sustainable resolution in diverse building environments to achieve various functions in terms of lightweight, ductility, as well as energy absorption. This study explored the 3D printed rubberised cementitious composites (3DPRC) in two aspects: examining the effects of crumb rubber pretreatment conditions on compressive properties; conducting experimental and numerical analysis on the acoustic dissipation characteristics of 3DPRC. Fine crumb rubber granules (3-5 mm) replaced 10%, 20%, and 30% of river sand in the composites. Uniaxial compression tests indicated that the compressive strength of 3DPRC decreased with the increase of crumb rubber content and introduced anisotropic behaviour. Impedance tube tests were conducted to evaluate the sound absorption and insulation capabilities of 3DPRC. An optimal Noise Reduction Coefficient (NRC) of 0.35 was achieved with 30% crumb rubber. The sound insulation properties depend strongly on the mass density and porosity of the 3DPRC. Additionally, it is proved that the volume of built-in air gap has positive effects on both sound absorption and insulation properties. The results from Finite Element Method (FEM) numerical simulations correlated well with experimental data, proving the efficiency of the simulation and validating the experimental results.

Sound speed prediction of seafloor sediments in the South Yellow Sea based on BP-AdaBoost model

Based on the sound speed and physical property measurements of seafloor sediments obtained in the central part of the South Yellow Sea, a multi-parameter prediction model for the sound speed of seafloor sediments based on seven parameters, including density, porosity, water content, liquid limit, plasticity index, compression coefficient, and median grain size, was developed by using the BP-AdaBoost fusion algorithm. The results show that the model, configured with 7 input layer neurons, 10 hidden layer neurons, 1 output node, a learning rate of 0.1, and 300 training iterations, achieved a correlation coefficient of 0.962. The mean absolute error (MAE) of the predicted sound speed was 10.19 m/s, and the mean relative error (MAPE) was 0.66%. These results are better than those of single-parameter and dual-parameter prediction equations and other machine learning models. The BP-AdaBoost model prediction method of sound speed of seafloor sediments established in this paper is better than the single-parameter and dual-parameter prediction equations and other prediction models, and it can provide a new way for the prediction of sound speed of seafloor sediments in the study area.