Sound Insulation Research Articles

Examination of the effect of air gaps on impact sound insulation performance of dry-type double floor system

The dry-type double floor system is a floor finishing structure widely installed for apartments and offices in Japan. However, after installing the double floor system, it is found that the impact sound insulation performance using a heavy-weight impact source is usually reduced due to the resonance of the air layer between the floor panels and the concrete slab. To reduce this adverse effect, small air gaps are set between the floor panels and the surrounding walls. In this paper, an experimental study is conducted firstly. A small specimen including particle board, support legs and air gaps is made to examine the effect of air gaps experimentally. Then, the air gaps are built as a Maxwell model considering that the air gaps act as the orifice of air spring. The theoretical analysis is conducted to explain the mechanism of impact sound insulation of the double floor system with or without air gaps. Finally, a parametric study is conducted to investigate the effect of air gaps with different dimensions on the impact sound insulation performance of the double floor system.

Simulating noise and vibrations on passenger ships using Statistical Energy Analysis

Various sources aboard a passenger ship contribute significantly to noise and vibration concerns. Notably, fluctuating pressure loads on the hull can result in elevated noise levels within rooms near the propulsion. Expensive solutions of sound insulation such as floating floors are employed to reduce these levels. Nowadays, designing these treatments is mainly based on empirical studies. However, the limited availability of the ship, the laborious nature of experiments, and the possibility of solutions being oversized have only increased the method's constraints. Utilizing calculation methods can save time, reduce additional weight on the ship, and provide more tailored design solutions. A Statistical Energy Analysis (SEA) has been used as deterministic approaches are often not suitable for the frequency range of interest for full-scale structures. The validation process for the wave-based SEA method involves several steps. Initially, simple models are constructed to establish correlations between local airborne and structure-borne energy transmission using simple acoustic loads, as well as to assess the method's scope of application. Subsequently, this approach is applied to larger models, such as the aft full part of the ship, enabling the prediction of noise levels and energy transmission paths under real loads.

Wall sound insulation measurement in laboratory according to iso 10140-2 standard and sound insulation measurement on the same wall with electrical and telephone sockets

Study related to the measurement of acoustic insulation R to sand and cement block wall with flattening on both sides, which was built inside a Transmission Chamber in accordance with the ISO 10140-2 standard. Subsequently this wall is slotted, placing Conduits, accessories for illumination, electrical and telephone sockets on both sides, finally covering all these installations with products that make it appear that the wall is intact, then the measurement of its acoustic insulation R and Rw is carried out. The results indicate variations that can be very annoying for residents on both sides of the wall, highlighting the lack of sealing into the Conduits, the choice of materials, location of sockets and construction procedures, etc.

Floor impact sound insulation performance of Korean domestic cross-laminated timber floors and the influence of resilient materials' dynamic stiffness

In this study, the floor impact sound insulation performance of floors made of korean domestic cross-laminated timber panels and with a resilient layer under concrete topping was evaluated. The properties of resilient materials used in the floors were measured to evaluate their influence on floor impact sound insulation performance. The results indicate that the highest reduction levels were provided by glass fiber, expanded polystyrene and wood fiber, in diminishing order, for both heavy-weight and light-weight floor impact sounds. Through the evaluation of dynamic stiffness and single-number quantities, a high correlation was observed at 125 Hz and 500 Hz for heavy-weight floor impact sounds and across all octave bands for light-weight floor impact sounds. The analysis of dynamic stiffness and single number quantity revealed a high correlation in both heavy weight and light weight floor impact sound. Lower dynamic stiffness was confirmed to be advantageous for reducing floor impact noise.

Comprehensive evaluation on wearing and hearing comfort of over-ear headphones based on adjustable clamping force

Headphones are wearable devices that directly contact the human body. Ergonomics focuses on the wearing comfort associated with clamping force, which is closely related to the user's tactile perception. Additionally, as auditory input terminal devices, headphones should also encompass the aspect of hearing comfort. Theoretically, slight and uneven clamping force may cause noise exposure, subsequently influencing hearing comfort. Conversely, an overloaded clamping force, while aiming to improve hearing conditions, may introduce discomfort for the wearer. Therefore, the current work concerns the interplay between wearing and hearing comfort. In this study, four loudspeakers placed around a listener in a sound insulation room render a stable noise environment. A dynamometer mounted on a horizontal track radially supplies specific clamping force on the two earmuffs of an over-ear headphone worn by the listener. Simultaneously, a comfort questionnaire was employed to investigate users' subjective perceptions of wearing and hearing comfort under various clamping forces. These results could provide a valuable reference for the design and evaluation of over-ear headphones.

Ventilation and windows in The Netherlands

The Dutch Building decree gives rules for the ventilation and sound insulation of facades. In the standards a lot of possibilities are described to fulfil these requirements. In this paper the most frequently used methods are described. It also became clear that in the course of the last 40 years some methods for natural ventilation are not in use any more for newbuilt dwellings because of problems with insect-nuisance and housebreaking. Therefore special ventilation grids and muffles are in use to fulfil the requirements both for ventilation and sound insulation of facades. In that case open windows play no role in case of ventilation but only when people want to get fresh air in a short time by opening windows on both sides of the dwelling. In that case there are no requirements for sound insulation of facades. In this paper the fulfilling of the sound insulation of facades and ventilation are described .

Impact sound insulation performance of floor coverings in a heavyweight reference floor with a floating floor

This study investigates the impact sound reduction performance of floor coverings used on the heavyweight standard floor of a floating floor structure in comparison with bare slab testbeds through on-site experiments. The laboratory performance evaluation of floor coverings designates only a bare slab between 100 mm and 160 mm as the heavyweight reference floor according to Annex C in ISO 10140-5. However, the recent expansion of over-floor heating systems has led to an increased need for understanding the impact sound reduction performance of floor coverings on floating floors, to enhance occupants' thermal comfort. In this study, it was measured the heavyweight and lightweight floor impact sound reduction levels of various floor covering test specimens in testbeds with different thicknesses of bare slabs and actual apartment houses with floating floors applied. The reduction rate for each frequency band was determined before and after installing floor coverings including single number quantity in accordance with ISO 717-2. Additionally, the impact of heavyweight reference floor conditions on quantifying the sound performance of floor coverings was discussed.

Investigation of the sound insulation and natural ventilation performance of a metamaterial-based open window

Recent advancements in metamaterials have created new opportunities to enhance indoor environmental quality (IEQ) by integrating natural ventilation and sound insulation in architectural designs. Metamaterial-based windows can facilitate natural ventilation, contributing to energy savings while also protecting against outdoor noise. However, international standards for assessing façade sound insulation typically assume all partitions are closed, with only the Danish standard DS 447:2021 accounting for partially open conventional windows. These standards do not address simultaneous noise mitigation and natural ventilation. To fill this gap, this study evaluated a prototype metamaterial-based device called the Acoustic Metawindow (AMW) unit using three experimental methods. These methods included the diffuse field method (ISO 10140 series), an adapted directive sound field method (EN 1793-6), and beamforming to control sound leakages from the AMW unit in both closed and open states. Additionally, the study used an adapted ISO 9972 method to assess the ventilation potential alongside sound insulation of the open AMW unit. The findings revealed that the AMW unit significantly outperformed equivalently open windows, achieving a sound level difference (Dn,e) improvement of 5–15 dB in the 500–5000 Hz frequency range, resulting in a total Dn,e,w of 30 dB. The study also indicated a correlation between the frequency range of effective sound insulation and the metamaterial design features of the AMW unit. This research suggests the possibility of a more inclusive standard that considers partially open sound-insulating devices as windows in the built environment, combining noise mitigation and energy saving.

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.

Lightweight and hydrophobic silica aerogel/glass fiber composites with hierarchical networks for outstanding thermal and acoustic insulation

Silica aerogels are regarded as potential thermal and acoustic insulation materials with low density and porous structure. However, the hydrophilicity due to surface hydroxyl groups and the low mechanical intensity have limited its further application. Generally, it can be achieved by adjusting the process parameters of the sol-gel to refine the structure of silica aerogels and optimize performance. In this study, we adopted an appropriate modification strategy of incorporating glass fiber felts as the reinforcing phase and trimethylchlorosilane (TMCS) as the hydrophobic modifier. By adjusting the solvent exchange time, the micro-nano structure, i.e. hierarchical networks, was optimized. The TMCS-modified silica aerogel/glass fiber/hot-melt fiber composites (TSGMs) exhibited great sound insulation, and the maximum sound transmission loss (STL) was up to 34 dB at 6300 Hz. Compared to unmodified, STL improved by 8 dB in simulated practical applications. In addition, TSGMs also exhibited high hydrophobicity with a water contact angle of 147° and excellent thermal insulation with a thermal conductivity of 0.0345 W (m k)-1. The results could contribute to the refinement in the preparation process of silica aerogel composites and use in the fields of thermal and acoustic insulation.

Implementation of Active Noise Canceling for Noise Reduction using Embedded System

Abstract This paper presents the utilization of active noise canceling (ANC) technology using an embedded system for a sound insulation box. The ANC system for the insulation box is designed to replace conventional heavyweight passive sound absorber systems. A feedback filtered-x least mean square (FxLMS) algorithm is utilized to create the opposing-noise signal to counteract the incoming noise entering the box, so that reducing the noise level inside the box. In our previous work, we delved into a similar topic of using ANC for a sound insulation box, but the prior system had limited performance due to its inability to operate in real time. In this study, the FxLMS algorithm is implemented on an ARM Cortex-based microcontroller development board. A feedback structure is utilized, with an error microphone positioned in the middle of the box The ANC system’s capability was evaluated for pure tone noise in the frequency range of 63 Hz to 630 Hz. The experimental findings indicate that the ANC system has the capability to cut back the noise level up to 4 dB for some frequencies.

Development and Characterization of a Flexible Soundproofing Metapanel for Noise Reduction

This study addresses the critical challenge of developing lightweight, flexible soundproofing materials for contemporary applications by introducing an innovative Flexible Soundproofing Metapanel (FSM). The FSM represents a significant advancement in acoustic metamaterial design, engineered to attenuate noise within the 2000–5000 Hz range—a frequency band associated with significant human auditory discomfort. The FSM’s novel structure, comprising a box-shaped frame and vibrating membrane, was optimized through rigorous finite element analysis and subsequently validated via comprehensive open field tests for enclosure-type soundproofing. Our results demonstrate that the FSM, featuring an optimized configuration of urethane rubber (Young’s modulus 6.5 MPa) and precisely tuned unit cell dimensions, significantly outperforms conventional mass-law-based materials in sound insulation efficacy across target frequencies. The FSM exhibited superior soundproofing performance across a broad spectrum of frequency bands, with particularly remarkable results in the crucial 2000–5000 Hz range. Its inherent flexibility enables applications to diverse surface geometries, substantially enhancing its practical utility. This research contributes substantially to the rapidly evolving field of acoustic metamaterials, offering a promising solution for noise control in applications where weight and spatial constraints are critical factors.

House FIRSTLIFE in student contest and in Living Lab

Abstract The paper comments on selected measurements and observations related to the FIRSTLIFE house demonstration unit, which was prepared by the team of the Czech Technical University for the international competition Solar Decathlon Europe 21/22 with its final at the Solar Campus in Wuppertal, Germany. The paper comments on the measurement results obtained during the competition in the field of building physics (thermal and moisture comfort, measurement of air permeability, measurement of sound insulation of the perimeter wall and dynamic co-heating test). The second part of the paper describes selected follow-up activities. For the purposes of the Living Lab, eight of the competition houses remained on the Solar Campus for at least another 3 years. This allowed long-term monitoring and targeted experiments to be carried out and some of the earlier measurements to be repeated under different climatic boundary conditions. For this phase, additional sensors were added in the Czech house, such as a meteorological station and temperature and heat flow sensors in the perimeter wall. Part of the data comes directly from the building management system. The paper comments on first results from Living Lab period.

Sound Insulation Characteristics of Sandwich Thin-Plate Acoustic Metamaterial: Analysis and Optimization

Addressing the demand for low-frequency noise control in ships and aiming to overcome the limitations imposed by the mass law of traditional materials, a sandwich thin-plate acoustic metamaterial (SPAM) was developed in this study. This structure is characterized by its simplicity and superior sound insulation performance. A sound insulation test was conducted to validate the exceptional low-frequency acoustic suppression capability of SPAM, and the effectiveness of the analytical model was also demonstrated. Subsequently, based on this model, a sensitivity analysis of the sound insulation characteristics of the SPAM relative to structural parameters was carried out. For the optimization process, the Logistic-Sine fusion chaotic mapping was employed to refine the dung beetle optimizer (DBO), enhancing the initial population distribution. The improved dung beetle optimizer (IDBO) was then used to further optimize and elevate the sound insulation performance of the SPAM. The outcomes indicate that the IDBO boasts superior optimization proficiency and accelerated convergence, while the optimized SPAM exhibits more remarkable sound insulation capabilities. Within the frequency range of 100–315[Formula: see text]Hz, the average sound transmission loss (STL) has increased by 11.94[Formula: see text]dB when compared to the pre-optimization values.

Comparison of Sound Insulation Performance of Water Drop and Trapezoidal Sound Barriers

Comparison of Sound Insulation Performance of Water Drop and Trapezoidal Sound Barriers

A novel acoustic micro-perforated panel (MPP) based on sugarcane fibers and bagasse

Natural materials are becoming a reliable alternative to traditional artificial materials used in sound absorption insulation. The present study was conducted to investigate the acoustic insulation of micro-perforated panel (MPP) based on sugarcane fibers and bagasse as an available and environmentally friendly material. The absorption properties of single- and double-leaf natural micro-perforated panels (MPP) made of bagasse and also nonnatural MPPs made of Plexiglass were measured using an impedance tube based on ISO 10534–2. Then the effect of bagasse and sugarcane fibers composite on the air gap of MPP was investigated. The results showed the peak sound absorption of the bagasse composite is in the range of 1000 to 2000 Hz, and the sugarcane fiber composite has a higher sound absorption coefficient than the bagasse composite. Also, natural MPPs have a higher absorption coefficient than nonnatural MPPs at all frequencies, and as the panel thickness increases, the peak absorption coefficient shifts to lower frequencies. The peak sound absorption coefficient of double-leaf MPPs made of bagasse is 76%, in the range of 160 to 200 Hz. Using sugarcane fiber composite in the air gap of single- and double-leaf natural MPPs causes the absorption peak to shift to frequencies below 100 Hz. According to the results, natural MPPs have a high sound absorption coefficient at low frequencies. These panels can control sounds with much lower frequencies, especially in a double layer and along with cane fiber composite in their air gap.

Acoustic metaslit for regional sound insulation for a three-dimensional diffuse sound field incidence

An acoustic metaslit model designed for regional sound insulation, employing waveguide modes and the directivity of openings, is introduced. This model characterizes the frequency responses of numerical simulations. The performance of metaslits, made from steel plates, is experimentally validated under diffuse sound field conditions and assessed by measuring acoustic power differences using intensity probes. The frequency response of single and multiple-unit metaslits shows peaks at multiples of the target frequencies. Additionally, experimental results demonstrate that the three-dimensional structure does not influence the two-dimensional regional sound insulation phenomenon. Furthermore, comparisons between experimental and numerical results indicate that obstacles near the outlets of metaslits can impact their performance.

Sound Insulation of an Acoustic Barrier with Layered Structures of Sonic Crystals – Comparative Studies of Physical and Theoretical Models

Sound Insulation of an Acoustic Barrier with Layered Structures of Sonic Crystals – Comparative Studies of Physical and Theoretical Models

A review on serviceability of foam concrete

In the face of the present global warming crisis, building energy conservation and emissions reduction have gained increasing attention. In the sustainable development of buildings, foam concrete has become increasingly popular in the construction industry due to its excellent thermal insulation, sound insulation and fire resistance. Foam concrete employed in buildingand construction (used as either a structural or non-structural member) must meet certain serviceability criteria. This paper reviews the serviceability of ordinary Portland cement (OPC) foam concrete, geopolymer foam concrete (GFC), sulphoaluminate cement (SAC) foam concrete, magnesium phosphate cement (MPC) foam concrete and limestone calcined clay cement (LC3) foam concrete, to include drying shrinkage, creep, thermal conductivity, water absorption and acoustic properties. Subsequently, it is proposed to change the initial curing conditions to reduce drying shrinkage, add glass fiber and basalt fiber to improve creep performance, increase heat flow direction resistance and extend the thermal conduction path to reduce thermal conductivity, control slump flow to regulate water absorption, and combine sound absorbing foam concrete with sound reflecting materials to achieve a comfortable and low noise living environment. Finally, ideas and suggestions for future work are proposed.

Acoustic optimization design for the laying schemes on the composite roof structure of high-speed train

ABSTRACT If the weak sound insulation in the roof during high-speed train travel through tunnels can be addressed by adjusting the order of materials, this will meet design requirements for both economy and lightweight construction. This paper studies this problem. First, a prediction model for sound transmission loss (STL) of the roof was established to investigate the impact of different material placement schemes and optimize their arrangement. Then, the optimal placement schemes between the roof and floor were compared using STL tests. Finally, this study also examined how an optimal scheme mitigates power radiation from the roof into the train interior under typical mechanical excitations. The results indicate that the optimal laying scheme for the roof differs from that of the floor. By placing sound absorption materials on the inner side of aluminium extrusion and sound insulation materials on decorative plate, it effectively enhances vibro-acoustic characteristics of the roof.