Vehicle Interior Research Articles

Flexible Coated Conductive Textiles as Ohmic Heaters in Car Seats

Pleasant interior conditions within cars, as well as a comfortable feeling, are primary needs of car drivers to perform vital body functions during driving. In a cooler outer environment, a warming system within seats can quite feasibly maintain a realistic thermal balance in the body. An inbuilt heating system in car seats can not only provide adequate heat to the driver but is also relevant to minimizing the energy consumption within the vehicle interior. In order to evenly distribute the heat over the body contact area of the automotive seats, conductive textiles are proposed. In fact, these textiles behave as a semiconductor (as an electrical conductor and also creating resistance, which in turn creates heat). Flexible textile ohmic heaters present great advantages due to their ability to bend, stretch, and stitch. These properties make them valuable to ensure uniform heaters for irregular geometries. The present review highlights the use of different textile-based ohmic heaters, their fabrication methods, range of heating, and durability. Moreover, this review also focuses on the comparative mechanical performance and comfort properties of the presented fabrics (used in car seats). This study is beneficial for future trends of minimizing energy consumption and providing an effective way to reduce the carbon emissions and air pollution produced by vehicles.

Spatial Integration of Dynamic Auditory Feedback in Electric Vehicle Interior

Spatial Integration of Dynamic Auditory Feedback in Electric Vehicle Interior

Research on odor characteristics of typical odorants of railway vehicle products.

Odor annoyance was a kind of environmental air pollution. Compared to other indoor environments, vehicle interior materials were not well studied. Especially, there had been little research on odor character of the railway vehicles. This study applied the OAV method to identify the key odorants of railway vehicle materials and discussed the characteristics of these odorants through Weber Fechner law and a dual variable method. The result showed that for single odorant, Weber Fechner law can be used to estimate the perceived intensity of an odor gas sample at different concentration levels. The odorant with smaller slope had significant tolerance to human. For the mixtures of odorants, the overall intensity of the mixture is generally dominated by the strongest odor intensity of the individual substance in the mixture, and positive interaction effect can be observed in mixtures whose intensities had little difference. But there was a kind of odorants, such as methacrylate, in which a very small variation in the concentration of mixtures can affect its odor intensity largely. Meanwhile, the odor intensity modification coefficient was an effective way to identify and evaluate odor interaction effect. The interaction potential of the studied odorants from strong to weak was methacrylate, dibutyl-amine, nonanal, 2-ethyl hexanol. The odor interaction potential and odor nature should be paying much attention in the improvement of odor in railway vehicle product.

New car odor: sensory and molecular characterization of odors and potential sources of smell in the vehicle interior

The typical new car smell is very distinctive. Depending on vehicle brand and class, this characteristic odor differs in intensity and elicits either approval or rejection among vehicle purchasers. Up to now, only limited information has been available on the molecular composition of the new car odor. Vehicle manufacturers (OEMs) are mainly concerned with the analysis of toxic compounds and (odorless) main components of the gas phase of the vehicle interior. In addition, OEMs usually do not have an appropriate equipment to characterize odorants by instrumental analysis. Therefore, this work deals with the investigation of odors and potential sources of smell in the vehicle interior. In the first two chapters of this thesis, odor‐active compounds of an aqueous cavity preservation were analyzed by means of solvent extraction, gas chromatography‐olfactometry (GC‐O) and odor extract dilution analysis (OEDA). Odorants of the investigated corrosion inhibitor could enter the vehicle interior via air bridges between the vehicle body and the passenger cabin and could have a considerable influence on the odor. Identification of the potent odors by twodimensional gas chromatography‐mass spectrometry coupled with olfactometry (2D‐GC‐ MS/O) revealed a series of carboxylic acids and lactones as the main odor contributors of the cavity preservation. The hardening of the cavity preservation affected a change of the odor profile due to the evaporation of odor‐potent lactones which was confirmed by a descriptive odor profile analysis. A comparison with odorants of individual materials of the vehicle interior investigated in literature revealed that both identified substance classes are present in a wide variety of materials and, consequently, contribute to the odor in the vehicle interior. In the third chapter of this thesis, odorants of the aqueous cavity preservation were investigated by means of emission test chamber experiments with the aim to obtain further insights into the odorant composition. Since no appropriate method existed to investigate odorants in a gas phase in the form of a liquid odor extract, different sampling strategies, such as chamber air absorption and adsorption, were compared. Subsequent investigations by GC‐O and OEDA revealed potent carboxylic acids and lactones in the gas phase of the heated cavity preservation using each sampling method. In addition, more detailed results were obtained in a descriptive odor profile analysis by sample presentation of chamber air in odor bags compared to a presentation in glass vessels according to VDA 270. As a result, the developed methods may be extended for the investigation of odorants in air of big vehicle assemblies or whole vehicle interiors. In the fourth and the fifth chapter of this thesis, odorants of two new car interiors with different seat covers were analyzed as general proof of principle. For this purpose, air of the vehicle interiors was investigated in a whole vehicle test stand for interior emissions by means of adsorption and subsequent elution of the volatiles. Following GC‐O and 2D‐GC‐MS/O analyses, 39 odorants were identified belonging to various substance classes such as esters, saturated and unsaturated aldehydes, unsaturated ketones, rose ketones, phenol and benzene derivatives, and pyrazines. Furthermore, ten important odorants were quantified which could be detected in a descriptive odor profile analysis. After the initial investigation, both vehicles were used by a customer in his everyday life. At specific time intervals during use, the odorant composition of the vehicle cabins was analyzed by means of sensory evaluation and instrumental analysis after sampling on the test stand for interior emissions. The knowledge of the decay behavior of the odorants allowed further pinpointing of the most important odorants that caused the typical new car odor in the two investigated cars during vehicle usage. Based on these findings, a targeted investigation of individual components regarding the identified odorants and, thus, a reduction of the exposure to smelly substances in the vehicle interior will be significantly facilitated.

Research on active sound control in EV in-vehicle based on engine order sound fitting

In order to upgrade the comfort and dynamic feeling of the sound in the cabin of electric vehicle acceleration and uniform driving, this paper conducted a study on active sound making control in EVs based on sound fitting. Sound fitting was analyzed by short-time Fourier technique (STFT), sound extraction and synthesis was tested by STFT and synthesis method was conducted by Kaiser window function. A study on the sound requirements of a Class A EV was completed, in which a sound design method integrated three objective dimensions of sound amplitude strengthening, energy distribution, and order composition in the vehicle speed range, so as to determine the sound design scheme of accelerated driving with both comfort and dynamic sense. By comparing the characteristics of two kinds of engine sound extraction, the correlation between dynamic sensation and engine sound amplitude was analyzed, and the active sound parameter selection was confirmed under two conditions of acceleration and uniform speed. Efforts were devoted to conduct the active sound system program workflow diagram and system hardware design and testing, and to complete the active sound generation system (ASGS) formation and accuracy testing of the electric vehicle based on the audio system speaker, and additionally the sound calibration and target verification of the ASGS under the static conditions of the real vehicle were carried out. The objective test shows that the ASGS reduces the sharpness under the two working conditions of acceleration and constant speed to 1.0 and 0.52 acum respectively, which effectively alleviates the uncomfortable feeling brought by the high-frequency order sound, and proves that the ASGS can enhance the comfort and dynamic quality characteristics of the electric vehicle interior sound.

A Case Study Comparing Active Vs. Passive Enablers for Vehicle Interior Noise Reduction

The implementation of enablers on a luxury sport utility vehicle is used to illustrate the development process for reduction of road noise. The vehicle in this case study was launched into production with two tuned mass dampers for reduction of low frequency road noise content which was amplified by frame modes. Additionally, resonators were integrated into the wheels (rims) to address the dominant cavity resonance frequencies. The results of this successful production implementation are illustrated herein. An RNC (road noise cancellation) system was integrated into the case vehicle to assess its performance relative to the passive enablers listed above. This production representative (embedded software solution) RNC system utilized the vehicle's existing audio system for creation of active noise to cancel noise content which was predicted using accelerometers mounted to the vehicle chassis. A comparison of in-vehicle noise indicated a significant reduction at low frequencies (at all seating locations) when utilizing the active noise control solution. These noise improvements are coupled with a vehicle mass reduction of greater than 4 kg, when compared to the passive enabler solution.

A hybrid transfer function procedure for broadband auralization within small flight vehicle interiors

Auralization of the sound fields within flight vehicle interiors is of interest to aircraft designers considering crew and passenger ride quality. Computer models can be used to predict the filtering effects that the fuselage structure and interior volume have on the exterior sound field in order to simulate the resulting cabin interior noise. However, this can become expensive when a wide frequency range of analysis suitable for passenger auralization is desired. This is particularly the case when using deterministic modeling methods such as finite element analysis (FEA) wherein prohibitively high levels of detail and finite element discretizations are required to resolve the wavelengths at high frequencies. On the contrary, Statistical Energy Analysis (SEA), while not capturing important modal behaviors at low frequencies, is better suited for higher frequency analyses where structural and interior dynamics exhibit high modal overlap and spatially averaged physical quantities suffice. For this reason, a hybrid procedure is considered here that utilizes FE modal solutions at lower frequencies and SEA results at higher frequencies. A transfer function dataset containing the exterior to interior vibroacoustic filtering effect is calculated accordingly and subsequently stored to be used for a variety of exterior dynamic load cases. At low frequencies, the transfer function dataset detail is related to the level of

Development of Active Noise Control System Optimized for Road Noise Reduction

In this paper, a newly developed Active Noise Control (ANC) system is introduced, that effectively reduces road noise, which becomes a major issue with electrified vehicles, and that enhances vehicle interior sound levels matching seamless acceleration by electric drive. Conventionally, reducing road noise using ANC requires numerous sensors and speakers, as well as a processor with high computing power. Therefore, the increase in system cost and the complexity of the system are obstacles to its spread. To overcome these issues, this system is developed based on four concepts. The first is a modular system configuration with unified interface to apply to various vehicle types and grades. The second is the integration and optimal placement of noise source reference sensors to achieve both reduction in number of parts and noise reduction performance. The third is the application of digital communications that combine power superposition, low latency, and high throughput to reduce wiring. The fourth is the development of control technologies that specialize in in-vehicle acoustic characteristics to achieve both computational efficiency and noise reduction performance. The one is a technology to integrate control paths based on the sound field mode characteristics in the vehicle cabin, and another one is the frequency band restrain control technology that matches speaker output characteristics. It is confirmed that this proposed system achieves quietness improvement equivalent to the difference of vehicle segmentation with a minimum system configuration, and that this system has a high superiority in weight efficiency compared to conventional vehicle body measures.

Predictive Factors of the Fatality of Motor Vehicle Passengers Involved in Far-Side Lateral Collisions: A National Crash Database Study.

Although the risks faced by passengers in near-side lateral collisions are understood, and despite the presence of side airbags for injury prevention, passengers involved in far-side lateral collisions also suffer serious and fatal injuries. The objective of this study was to determine the independent predictive factors of fatality of motor vehicle passengers involved in far-side lateral collisions. Using 2010 records from the National Automotive Sampling System/Crashworthiness Data System (NASS/CDS), we selected 86 fatal and 325 non-fatal passengers with an Abbreviated Injury Scale (AIS) score of 2 or more. The background and injury severity of the passengers and collision characteristics were compared between the two groups. In a multivariable logistic regression analysis, variables independently associated with fatalities were female sex (Ref, male) (odds ratio [OR], 0.396), age (OR, 1.029), body mass index (OR, 1.057), total delta-V (OR, 1.031), head AIS score (OR, 1.679), chest AIS score (OR, 1.330), and abdomen AIS score (OR, 1.294). This is the first report to determine factors affecting fatality in passengers involved in far-side lateral collisions. Improving the safety of the vehicle interior, such as by including additional seatbelt systems or a side airbag that deploys between seats, might help to avoid fatalities, and reduce injury severity.

Modeling the perceptions of Rumbling, humming and booming in the context of vehicle interior sounds

Sensations associated with an auditory perception of low-frequency tonal components are humming, rumbling and booming. While humming is commonly associated with an audible low-frequency tone, rumbling requires a temporal level fluctuation of such a tonal component and booming is associated with sounds that, in addition to the low-frequency tone, contain higher tonal components, which are related to the low-frequency tone. This study presents a model that predicts the magnitude of these sensations for interior sounds of vehicles with combustion engines running at low rotation rates, where low-frequency components are often audible. For the model development, own experimental data of recorded interior sounds and altered versions of these sounds were used. The model combines an auditory processing model with a Gaussian Process Regression approach. Key features of the auditory processing model are that it simulates the frequency-place transformation at the auditory periphery with a bank of auditory band pass filters and the frequency selectivity to temporal amplitude modulations with a bank of modulation band pass filters. It is shown that auditory filters up to a center frequency of 1000 Hz and modulation filters of up to 28 Hz are required for a good prediction of the data.

System integration analysis of a zeolite 13x thermal energy storage

Nowadays a major energy transition aimed at cutting CO2 emissions has begun, with the ambitious goal of drastically reducing the dependence on fossil fuels and promoting the use of renewable energy sources. In this context, energy storage systems play a key role in ensuring a stable, secure and time-aligned energy availability. Open sorption thermal energy storages (TESs) can contribute to such transition, since they are simple and cheap devices able to provide a hot airflow with a high energy density and to store energy for long time. In this work, open sorption TES systems operated with Zeolite13X are investigated with a focus on the integration in practical applications. First, the experimental analysis and modelling of the sole TES system is described. Then, the integration of the TES at system level is carried out. The analysis evidences that a significant reduction of storage capacity occurs if air humidification is necessary before the adsorption process or afterwards to keep adequate indoor comfort conditions for the occupants. For the exemplary case study considered, an energy density of 150 kWhm−3 can drop to 40 kWhm−3 in case of complete compensation of the adsorbed water through a humidifier. This paper provides useful guidelines for evaluating the performance of a TES integrated system in terms of specific energy and efficiency. It also identifies applications involving high latent loads (e.g., swimming pools, locker rooms) or for which low relative air humidity is required (e.g. interior of vehicles to prevent condensation on windows) as particularly beneficial for using a TES system.

A Comprehensive Overview of Basic Research on Human Thermal Management in Future Mobility: Considerations, Challenges, and Methods

Thermal management in automobiles is necessary to minimize energy usage while achieving a high level of occupant thermal perception. As the freedom of in-vehicle activity increases with autonomous driving, considering convenience becomes even more important, and, at the same time, the need for thermal management in electric vehicles is expected to increase. While it is necessary to consider the characteristics of the future mobility environment, there is still a lack of research that takes into account these changes in thermal management and proposes future research directions. Therefore, the purpose of this study is to explore basic research directions based on national R&D project cases and to provide a comprehensive overview. The environmental changes that need to be considered in thermal management research include the diversification of future transportation types and usage purpose diversification, the characteristics of electric vehicles, changes in the interior and exterior design of autonomous vehicles, personalized air conditioning environments, and dynamic thermal management according to occupant in-vehicle activity. This study provides an understanding of the overall field, and can help identify challenges, solutions, and ideas. Although this study provides conceptual considerations for research directions, future research is needed to identify detailed factors related to technology, environment, and human factors.

Effects of an integrated safety system for swivel seat arrangements in frontal crash.

Objective: Autonomous vehicles (Avs) have paved the way for the arrangement of swivel seats in vehicles, which could pose a challenge to traditional safety systems. The integration of automated emergency braking (AEB) and pre-pretension (PPT) seatbelts improves protection for a vehicle's occupant. The objective of this study is to explore the control strategies of an integrated safety system for swiveled seating orientations. Methods: Occupant restraints were examined in various seating configurations using a single-seat model with a seat-mounted seatbelt. Seat orientation was set at different angles, from -45° to 45° with 15° increments. A pretension was used on the shoulder belt to represent an active belt force cooperating with AEB. A generic full frontal vehicle pulse of 20mph was applied to the sled. The occupant's kinematics response under various integrated safety system control strategies was analyzed by extracting a head pre-crash kinematics envelope. The injury values were calculated for various seating directions with or without an integrated safety system at the collision speed of 20mph. Results: In a lateral movement, the excursions of the dummy head were 100mm and 70mm in the global coordinate system for negative and positive seat orientations, respectively. In the axial movement, the head traveled 150mm and 180mm in the global coordinate system for positive and negative seating directions, respectively. The 3-point seatbelt did not restrain the occupant symmetrically. The occupant experienced greater y-axis excursion and smaller x-axis excursion in the negative seat position. Various integrated safety system control strategies led to significant differences in head movement in the y direction. The integrated safety system reduced the occupant's potential injury risks in different seating positions. When the AEB and PPT were activated, the absolute HIC15, brain injury criteria (BrIC), neck injury (Nij), and chest deflection were reduced in most seating directions. However, the pre-crash increased the injury risks at some seating positions. Conclusion: The pre-pretension seatbelt could reduce the occupant's forward movement in the rotating seat positions in a pre-crash period. The occupant's pre-crash motion envelope was generated, which could be beneficial to future restraint systems and vehicle interior design. The integrated safety system could reduce injuries in different seating orientations.

Randomized learning-based classification of sound quality using spectrogram image and time-series data: A practical perspective

Audio classification is an important research topic in the deep learning field, and classification accuracy has developed exponentially. However, as the model performance increases, it becomes difficult to apply it to actual industrial data owing to limitations such as the requirement of a large amount of data or increased training time. In this study, we developed a method for a small dataset with ambiguous classification boundaries, similar to most industrial data. We used randomized learning methods to reduce the training time and the risk of overfitting that required low computing time and few hyperparameters. Vehicle interior noise data were used as industrial data. The data were classified into luxury, powerful, and sporty, according to the human emotional reactions. Data was recorded from approximately 300 vehicles in the same environment and preprocessed into two types: spectrogram images and time-series data. Through deep fuzzy c-means clustering, it was confirmed that the classification boundary of the vehicle interior noise data was ambiguous. We selected the random vector functional link (RVFL), deep RVFL, and random kernel transformation (ROCKET) as randomized learning methods and compared the results with convolutional neural network and long short term memory. RVFL and deep RVFL showed similar classification accuracy to deep learning but significantly reduced training time by approximately 99%. In the case of ROCKET, the training time was reduced by approximately 91% and the classification performance was improved by approximately 3%. In addition, all randomized learning methods have few hyperparameters, which significantly reduces the classification model design time.

Vehicle Wash Services Android Application

Vehicle wash facilities are primarily concerned with cleaning the exterior and sometimes the interior of vehicles in addition to their exteriors. The majority of people today own a vehicle, so keeping it clean can be a time- consuming undertaking since so many people own them these days. This burden can be alleviated by our solution, which connects vehicle owners with individuals who are willing to clean their vehicles for a fee in exchange for the money they pay for their services. With the help of our mobile app, owners can easily find and contact service providers who are willing to offer cleaning services for their vehicles. In order to book a service, customers simply need to submit an inquiry and provide their location, which will then be sent to all the active service providers. Key Words: Android App, Vehicle Wash, Location

Constant Power Psychoacoustic Spectrum Optimization for Loudness and Sharpness with Application to Vehicle Interiors

<div>Sound quality assessments are an integral part of vehicle design. Especially now, as manufacturers move towards electrification, vehicle sounds are fundamentally changing. By improving the quality of the interior sounds of a vehicle, consumers’ subjective evaluation of it can be increased. Therefore, the field of psychoacoustics, which is the study of human perception of sound, is broadly applicable here. In fact, the perceived quality of a sound signal is influenced by several psychoacoustic indicators, including loudness, sharpness, and roughness. Of particular utility is identifying in advance how to distribute audible frequency content in a way that optimizes psychoacoustic metrics as this can help automotive engineers obtain specific design targets that optimize vehicle noise, vibration, and harshness (NVH).</div> <div>In this article, a novel modified gradient-based optimization technique (MGOT) is developed to optimize psychoacoustic loudness and sharpness. The new technique is applied to identify targeted adjustments to a measured vehicle interior sound signal that keep the signal energy constant but reduce loudness and/or sharpness. The MGOT numerically approximates the objective function gradient for small changes in the signal power distribution for which constant overall signal power is maintained. These gradient calculations identify power spectrum one-third octave band trades that minimize a sound signal metric that is a weighted sum of loudness and sharpness while conserving the total signal power. A trade consists of a reduction of power content from a one-third octave band designated as a source together with a simultaneous addition of that power to another receiver one-third octave band. In the MGOT, a one-third octave band that is at any time identified as a source can never later become a receiver of power. The MGOT results and execution times are compared with two widely available general-purpose optimization routines (a standard gradient-based optimizer and a “genetic,” non-gradient optimizer) are used to achieve identical optimization objectives. In comparison to existing optimization techniques, MGOT is found to identify spectrum modifications that produce a superior minimization of the objective function for comparable or even reduced execution times. The resultant sound spectrum modifications can guide vehicle structural or calibration design recommendations that realize a preferred frequency distribution for enhancing the vehicle driving experience.</div>

A computationally efficient feedforward time–frequency-domain hybrid active sound profiling algorithm for vehicle interior noise

Active sound profiling (ASP) is gaining ever-increasing attention owing to its powerful ability to balance the sound pressure levels of certain frequency points or frequency bands of target noise for sound quality enhancement. Most of the current ASP algorithms, however, only focus on narrowband or broadband noise alone and the computational efficiency is very low. To alleviate this problem, a feedforward time–frequency-domain hybrid active sound profiling (TFD-HASP) algorithm is proposed in this paper. The algorithm consists of three subsystems, in which the narrowband ASP (NASP) subsystem utilizes the time-domain internal model FXLMS algorithm along with the local secondary path estimation approach, the broadband ASP (BASP) subsystem is based on the delayless frequency-domain internal model FXLMS algorithm, and the sinusoidal noise canceller (SNC) subsystem is designed to eliminate narrowband interference to the BASP subsystem. In this way, the presented TFD-HASP algorithm not only has good spectral reshaping capability for both narrowband and broadband noise components, but also requires notably low computational effort. A series of simulations are performed to evaluate the performance of the TFD-HASP algorithm. In addition, the comfortable sound quality of a real vehicle interior noise at high speed is designed and realized. Experimental results demonstrate that the proposed algorithm achieves satisfactory active sound profiling for noise with both narrowband and broadband characteristics.

Adaptive parallel filter method for active cancellation of road noise inside vehicles

Active noise cancellation (ANC) is an efficient and effective method for suppressing low frequency disturbances generated by tyre–road interaction in a vehicle. There are significant differences in road noise inside the vehicle under different driving conditions. However, fixed-filter ANC strategies are unable to achieve superior noise attenuation for different types of noise, and conventional adaptive algorithms require prolonged adaptation which is detrimental to dynamic noise reduction. Thus, this study proposes an adaptive parallel filter method (APFM) that quickly responds to and suppresses varying vehicle interior road noises. The APFM is divided into two phases: the tuning phase and control phase. In the tuning phase, a set of potential noises is adopted to train the corresponding optimal fixed filters. During the control phase, the most appropriate parallel control filter is first selected for each frame based on a selection mechanism to minimise the energy of the estimated error signal. Then, a delayless variable step size normalised frequency-domain block adaptive filter algorithm is adopted to update the selected control filter. In addition, the computational complexity of the proposed APFM is analysed. Numerous simulations and real time in-vehicle experiments conducted using multi-channel ANC headrests have confirmed the feasibility and effectiveness of the proposed algorithm. It is evident that the APFM achieves fast noise reduction response and low steady-state error in attenuating varying in-vehicle road noise, and retains superior performance in the presence of non-pre-trained disturbances.

Passenger vehicle interior decontamination by low concentration hydrogen peroxide vapor following a wide area biological contamination incident.

To assess low concentration hydrogen peroxide (LCHP) (H2O2) vapor dispersed with a home humidifier for its ability to decontaminate vehicle interiors contaminated with Bacillus anthracis surrogate Bacillus atrophaeus spores. Efficacy of a vaporized 3% H2O2 solution was evaluated for liquid volumes, on/off vehicle heating, ventilation, and air conditioning (HVAC) system operations, and temperatures that ranged from 5 to 27°C. Survival of the spores was assessed by quantification of remaining viable spores with efficacy quantified in terms of mean log10 reduction. Decontamination efficacy after the 6-day dwell time increased when the 3% H2O2 liquid volume was doubled, increasing from 4-of-10 to 10-of-10 nondetects (zero colonies counted using standard dilution and filter plating) inside the vehicle cabin. Recirculating cabin air through the HVAC system during decontamination decreased efficacy to 6-of-10 non-detects. While no 6-log10 reduction in viable spores was observed on the cabin filter with the cabin filter kept in place, a 6-log10 reduction was achieved after its removal and placement in the cabin during treatment. Results from this study allow for informed decisions on the use of LCHP vapor as an effective decontamination approach for vehicle interiors.

New designs of sandwich panels to mitigate high-frequency noise inside space vehicles

Radiation of noise to the interior of a space vehicle during liftoff and transonic climb is a long-standing problem. To attenuate noise inside the crew compartment during launch and in-space operation, sandwich panels have been employed in the pressurized outer shell to passively reduce the exterior noise transmission. However, the layouts and the sound transmission loss of the implemented sandwich panels have not been made available for public release. Against this idiosyncratic practice, this study envisioned disseminating the know-how on the sound attenuation ability of dissimilar sandwich panels. To efficiently absorb and dampen the acoustic energy, the sandwich panels were specifically configured using a honeycomb core, felts and a closed cell aluminum-foam in the material lay-up. The face sheets of the sandwich panels consisted of either glass fiber-reinforced epoxy or carbon fiber-reinforced epoxy composites. The sandwich panels were tested as acoustic barriers to a diffuse sound field in a sound transmission suite. As found, an increase in the panel thickness brought a decrease in the anti-symmetric coincidence frequency of sandwich panels. A rubber damping layer in the material lay-up added limp mass to a sandwich panel and reduced the panel vibration at excitation frequencies beyond 500 Hz. Multiple felts reinforced the sound transmission loss of a sandwich panel by dissipating the acoustic energy into thermal energy at the felt interstices in the frequency regime beyond 315 Hz. In conclusion, this study proposed optimized sandwich configurations considering the constitutive materials, number of material layers, material layer thickness and stacking sequence. The optimized sandwich configurations could fairly deliver the demanded sound transmission loss in the high-frequency regime.