Innovative Approaches to Acoustic Comfort in Vehicles: Experimental Assessment and Strategic Noise Reduction Solutions
Source abstract
Abstract
This study presents a rigorous experimental investigation of in-cabin acoustic comfort across a heterogeneous set of road and special-purpose vehicles. Interior noise measurements were conducted on a total of 35 vehicles, comprising five vehicles from each of seven operational categories, grouped according to RNTR-2 regulations into three distinct vehicle classes: N1, N2, and N2G. The adopted research methodology ensures a unified, phenomenological, and experimental approach to the assessment of interior vehicle acoustics, enabling consistent data acquisition and comparative analysis across vehicle classes. Measurements were performed under both stationary and dynamic operating conditions using Class 1 precision instrumentation. The experimental results reveal systematic differences in acoustic performance between vehicle classes. While N1 and N2 vehicles generally comply with recommended comfort thresholds, N2G special-purpose vehicles exhibit significantly elevated interior noise levels, reaching up to 90 dBA during dynamic operation, together with increased variability at higher engine regimes. These findings highlight the influence of vehicle architecture, operational conditions, and mission-oriented design constraints on vibro-acoustic behavior. Passive noise control solutions based on advanced sound-absorbing and sound-insulating materials were further evaluated, demonstrating interior noise reductions of up to 10 dBA. The scientific contribution of this work lies in the establishment of a unified, reproducible methodology that enables direct cross-category comparison of in-cabin acoustic comfort while explicitly integrating special-purpose vehicles into a comfort-oriented analytical paradigm. By moving beyond regulatory compliance toward a multidimensional interpretation of acoustic comfort, the study provides a robust foundation for vehicle design optimization and supports the future development of dedicated comfort assessment standards.
Source: crossref · Quality: baseline
Research context
OpenAlex topics: Vehicle Noise and Vibration Control · Noise Effects and Management · Acoustic Wave Phenomena Research
SciVX discovery tags are terminology-based. OpenAlex topics are source-provided classifications.
Affiliations
Department of Industrial Engineering and Management, George Emil Palade University of Medicine, Pharmacy, Science, and Technology of Targu Mures, Nicolae Iorga Street, 1, 540088 Targu Mures, Romania
Doctoral School of IOSUD, George Emil Palade University of Medicine, Pharmacy, Science, and Technology of Targu Mures, Gheorghe Marinescu Street, 38, 540142 Targu Mures, Romania
Department of Management, George Emil Palade University of Medicine, Pharmacy, Science, and Technology of Targu Mures, Gheorghe Marinescu Street, 38, 540142 Targu Mures, Romania
Funding
University of Medicine, Pharmacy, Science, and Technology “George Emil Palade” of Târgu Mureș
References (95)
Show source-provided references
1. Semmens, R., Martelaro, N., Kaveti, P., Stent, S., and Ju, W. (2019, January 4–9). Is now a good time? An empirical study of vehicle–driver communication timing. Proceedings of the 2019 chi Conference on Human Factors in Computing Systems, Glasgow, UK.10.1145/3290605.3300867 ↗
2. Assessing travel time savings and user benefits of automated driving—A case study for a commuting relation10.1016/j.tranpol.2020.03.007 ↗
3. Impact of trust and travel experiences on the value of travel time savings for autonomous driving10.1016/j.trc.2021.103354 ↗
4. Analysis of interior noise in special purpose vehicles
5. (1993). Design Guidance for Interior Noise Reduction in Light-Armored Tracked Vehicles (Standard No. MIL-HDBK-767 (MI)).
6. (1997). Design Criteria Standard: Noise Limits (Standard No. MIL-STD-1474D).
7. Noise and mental health: Evidence, mechanisms, and consequences10.1038/s41370-024-00642-5 ↗
8. National Institute on Deafness and Other Communication Disorders (2025, August 13). Noise-Induced Hearing Loss. U.S. Department of Health & Human Services, Available online: https://www.nidcd.nih.gov/health/noise-induced-hearing-loss.
9. A comprehensive review of auditory and non-auditory effects of noise on human health10.4103/nah.nah_124_23 ↗
10. (2025, February 10). Transport & Environment. New EU Vehicle Noise Limits. Transport & Environment. Available online: https://www.transportenvironment.org/articles/new-eu-vehicle-noise-limits-0.
11. Cherne, K.D. (1993). Motor vehicle noise regulations. SAE Technical Paper 931281, SAE International.10.4271/931281 ↗
12. (2022). Acoustics—Measurement of Noise Emitted by Accelerating Road Vehicles—Engineering Method. Part 3: Indoor Testing M and N Categories (Standard No. ISO 362-3).
13. United Nations Economic Commission for Europe (2007). Regulation No. 51–Uniform Provisions Concerning the Approval of Motor Vehicles Having at Least Four Wheels with Regard to Their Noise Emissions, UNECE. Revision 1, Addendum 50.
14. New comfort index during combined conditions of moderate low ambient temperature and traffic noise10.1016/j.enbuild.2004.08.001 ↗
15. Evaluation of sound comfort in examination hall using acoustical environmental analyses10.4028/www.scientific.net/AMM.315.825 ↗
16. Human comfort in indoor environment: A review on assessment criteria, data collection, and data analysis methods10.1109/ACCESS.2019.2937320 ↗
17. A real-time noise monitoring system based on internet of things for enhanced acoustic comfort and occupational health10.1109/ACCESS.2020.3012919 ↗
18. Bourikas, L., Gauthier, S., Khor Song En, N., and Xiong, P. (2021). Effect of thermal, acoustic, and air quality perception interactions on the comfort and satisfaction of people in office buildings. Energies, 14.10.3390/en14020333 ↗
19. People’s subjective and physiological responses to the combined thermal-acoustic environments10.1016/j.buildenv.2020.106709 ↗
20. Investigation of acoustic comfort, productivity, and engagement in naturally ventilated university classrooms: Role of background noise and students’ noise sensitivity10.1016/j.buildenv.2023.111131 ↗
21. A study on vehicle noise emission modelling: Correlation with air pollutant emissions, impact of kinematic variables and critical hotspots10.1016/j.scitotenv.2021.147647 ↗
22. Vehicle drive-by noise prediction: A neural networks approach
23. Health effects of transport noise10.1080/01441647.2023.2206168 ↗
24. Xu, J., Cruz-Machado, V., Lev, B., and Nickel, S. (2014). Metodologia TRIZ aplicată confortului fonic în avioanele comerciale. Proceedings of the Eighth International Conference on Management Science and Engineering Management, Advances in Intelligent Systems and Computing, Springer.10.1007/978-3-642-55122-2 ↗
25. Strategii de control pentru reducerea zgomotului de structură aeronautică10.1016/j.cja.2013.02.001 ↗
26. Crocker, M.J. (2007). Aircraft cabin noise and vibration prediction and passive control. Aircraft Cabin Noise and Vibration Prediction and Passive Control, Wiley.10.1002/9780470209707.ch119 ↗
27. Technologies for Aircraft Noise Reduction: A Review
28. The passive and active noise control strategy in the aircraft interior noise
29. Makarenko, V.M., and Tokarev, V.I. (2014, January 23–25). Passive method of inboard noise reduction for aircrafts. Proceedings of the Sixth World Congress “Aviation in the XXI-st Century”–Safety in Aviation and Space Technology, Kyiv, Ukraine.
30. Amirsalari, B., and Rocha, J. (2023). Recent advances in airfoil self-noise passive reduction. Aerospace, 10.10.3390/aerospace10090791 ↗
31. Kuo, C.Y., Hung, C.L., Chen, H.C., Shih, C.P., Lu, R.H., Chen, C.W., Hung, L.W., Lin, Y.C., Chen, H.K., and Chu, D.M. (2021). The immediate and long-term impact of military aircraft noise on hearing: A cross-sectional comparison of fighter pilots and ground staff. Int. J. Environ. Res. Public Health, 18.10.3390/ijerph18062982 ↗
32. Active noise reduction in aviation helmets during a military jet trainer test flight10.1080/010503901300007452 ↗
33. Hammond, D., McKinley, R., and Hale, B. (1998). Noise Reduction Efforts for Special Operations C-130 Aircraft Using Active Synchrophaser Control, Air Force Research Laboratory.
34. Hwang, K. (2022). Air Force Pilot’s Recognition About the Effectiveness of Active Noise Cancellation on Hearing Health, Performance, and Aviation Safety. [Ph.D. Thesis, University of Central Florida].
35. Robust active noise control system for fighter aircraft pilot helmet application10.1016/j.procs.2016.06.037 ↗
36. A review of industrial aeroelasticity practices at Dassault Aviation for military aircraft and business jets
37. Degrande, G., Lombaert, G., Anderson, D., de Vos, P., Gautier, P.-E., Iida, M., Nelson, J.T., Nielsen, J.C.O., Thompson, D.J., and Tielkes, T. (2021). Wheel–rail impact loads, noise and vibration: A review of excitation mechanisms, prediction methods and mitigation measures. Noise and Vibration Mitigation for Rail Transportation Systems, Proceedings of the 13th International Workshop on Railway Noise, Ghent, Belgium, 16–20 September 2019, Springer International Publishing.
38. Energy absorption design study of subway vehicles based on a scaled equivalent model test10.1177/0954409718777371 ↗
39. Effective sound-absorbing material for transport technological machines of railway transport10.1088/1757-899X/675/1/012045 ↗
40. Reducing railway noise with porous sound-absorbing concrete slabs
41. Research of noise emission sources in railway transport and effective ways of their reduction10.1051/matecconf/201710700073 ↗
42. Investigation of noise generated by railway freight wagon bogie type Y25Ls(s)e-K and proposals of noise reduction10.3390/vehicles4010008 ↗
43. Hecht, M. (2022). Railway noise reduction at the source only: Is this possible or mandatory?. INTER-NOISE and NOISE-CON Congress and Conference Proceedings, InterNoise22.10.3397/IN_2022_0056 ↗
44. Polak, K., and Korzeb, J. (2021). Identification of the major noise energy sources in rail vehicles moving at a speed of 200 km/h. Energies, 14.10.3390/en14133957 ↗
45. Railway noise annoyance on the railway track in northwest Slovakia
46. Decibel hell: The effects of living in a noisy world10.1289/ehp.113-a34 ↗
47. Araújo Alves, J., Neto Paiva, F., Torres Silva, L., and Remoaldo, P. (2020). Low-frequency noise and its main effects on human health—A review of the literature between 2016 and 2019. Appl. Sci., 10.10.3390/app10155205 ↗
48. Fit, A., and Duteurtre, X. (1995). Matériaux d’habitacle à fonction acoustique. Matériaux Pour l’isolation Acoustique des Machines et des Véhicules, CETIM.
49. Zimcik, D.G., Provencher, R.M., Lecheminant, R., and Mcnamara, D.A.J. (2025, May 22). Measurement of Noise in Armoured Personnel Carriers. National Defence Headquarters, Canada. Available online: https://apps.dtic.mil/sti/tr/pdf/ADA446765.pdf.
50. The applicability of ride comfort standards to off-road vehicles10.1016/j.jterra.2004.08.001 ↗
51. Index for vehicle acoustical comfort inside a passenger car10.1016/j.apacoust.2006.11.001 ↗
52. Vasile, O. (2009). Contribuții la Modelarea Controlului Zgomotului și Vibrațiilor/Contributions on Modelling of Noise and Vibration Control. [Ph.D. Thesis, Catedra de Mecanică, Facultatea de Ingineria Sistemelor Biotehnice, Universitatea Politehnica din București].
53. Cameron, C.J. (2011). Design of Multifunctional Body Panels for Conflicting Structural and Acoustic Requirements in Automotive Applications. [Doctoral Thesis, KTH Royal Institute of Technology].
54. The study on improvement of acoustic performance for automobile sound-absorbing materials using hollow fiber10.5050/KSNVE.2011.21.9.850 ↗
55. Duvigneau, F., and Gabbert, U. (2014, January 24–26). The sound reduction index applied to automotive problems. Proceedings of the 6th Aachen Acoustics Colloquium, Aachen, Germany.
56. Using nonwoven hollow fibers to improve cars interior acoustic properties10.1108/RJTA-16-03-2012-B005 ↗
57. Long, S., and Dhillon, B.S. (2015). The measurement and analysis of noise for a military vehicle. Proceedings of the 15th International Conference on Man–Machine–Environment System Engineering (MMESE 2015), Lecture Notes in Electrical Engineering, Springer.10.1007/978-3-662-48224-7 ↗
58. Acoustic metamaterials: A potential for cabin noise control in automobiles and armored vehicles10.1142/S1758825116500721 ↗
59. Acoustic energy absorption properties of fibrous materials: A review10.1016/j.compositesa.2017.07.002 ↗
60. Sound absorption with green materials10.1063/1.4990158 ↗
61. Noise of military weapons, ground vehicles, planes and ships10.1121/1.5134069 ↗
62. In-vehicle noise exposure among military personnel depending on type of vehicle, riding compartment and road surface10.1136/jramc-2018-001091 ↗
63. Hearing loss among military personnel in relation to occupational and leisure noise exposure and usage of personal protective equipment
64. Advanced materials used in the automotive industry—A review
65. Experimental investigation on motor noise reduction of unmanned aerial vehicles10.1016/j.apacoust.2020.107873 ↗
66. Application of sound package material in noise reduction of motor10.21595/vp.2021.21865 ↗
67. A review on polymer-based materials for underwater sound absorption10.1016/j.polymertesting.2021.107115 ↗
68. Necula (Stan), M. (2022). Împrăștierea Acustică pe Sisteme Complexe, Rigide și Elastice. [Ph.D. Thesis, Universitatea “Dunărea de Jos” din Galați, Școala Doctorală de Inginerie Industrială].
69. Yang, X., Tang, S., Shen, X., and Peng, W. (2023). Research on the sound insulation performance of composite rubber reinforced with hollow glass microsphere based on acoustic finite element simulation. Polymers, 15.10.3390/polym15030611 ↗
70. Zhang, H., Sun, Z., Zhi, P., Wang, W., and Wang, Z. (2024). Material-structure integrated design and optimization of a carbon-fiber-reinforced composite car door. Appl. Sci., 14.10.3390/app14020930 ↗
71. Military vehicle classification via acoustic and seismic signals using statistical learning methods10.1142/S0129183106008789 ↗
72. Astapov, S., Riid, A., and Preden, J.-S. (2016, January 3–5). Military vehicle acoustic pattern identification by distributed ground sensors. Proceedings of the 2016 15th Biennial Baltic Electronics Conference (BEC), Tallinn, Estonia.10.1109/BEC.2016.7743755 ↗
73. National Academies of Sciences, Engineering, and Medicine (2006). Noise and Military Service: Implications for Hearing Loss and Tinnitus, The National Academies Press.
74. Pietila, G., and Cerrato, G. (2011, January 9–11). Detection and identification of acoustic signatures. Proceedings of the 2011 NDIA Ground Vehicle Systems Engineering and Technology Symposium–Modeling & Simulation, Testing and Validation (MSTV) Mini-Symposium, Dearborn, MI, USA.10.4271/2024-01-3317 ↗
75. Moore, B.C.J. (2021). The effect of exposure to noise during military service on the subsequent progression of hearing loss. Int. J. Environ. Res. Public Health, 18.10.3390/ijerph18052436 ↗
76. Enabling robust communication among military ground vehicles using multi-connectivity10.4271/2023-01-0110 ↗
77. Tactical communications between military vehicles10.24018/ejphysics.2021.3.1.42 ↗
78. Touch-and-go: Interior tactile communication in armored fighting vehicles
79. Communication in military environments: Influence of noise, hearing protection and language proficiency10.1016/j.apacoust.2017.10.010 ↗
80. Effects of noise on speech recognition: Challenges for communication by service members10.1016/j.heares.2016.10.004 ↗
81. (2014). Directive on Measures Facilitating the Exercise of Rights Conferred on Workers in the Context of Freedom of Movement for Workers (Standard No. Directive 2014/54/EU).
82. (1979). Acoustics—Permissible Noise Levels in Industrial Environments (Romanian Standard) (Standard No. STAS 6926/16-79).
83. Electroacoustics—Sound Level Meters—Part 1: Specifications (Standard No. IEC 61672-1:2013).
84. (1992). Motor Vehicles. Noise Level and Methods of Test. Measurement of Inside Noise in Motor Vehicles (Standard No. STAS 6926/15-1992).
85. (1998). Military Vehicles—Method for Determining Interior Noise Level (Standard No. STP M 40527-98).
86. (1999). Military Vehicles—Method for Determining Exterior Noise Level (Standard No. STP M 40544-99).
87. (2010). Exterior Sound Level for Heavy Trucks and Buses (Standard No. SAE J366).
88. (2014). Sound Level for Passenger Cars and Light Trucks (Standard No. SAE J986).
89. (2015). Engine Sound Level Measurement Procedure (Standard No. SAE J1074).
90. (2003). Minimum Health and Safety Requirements Regarding Workers’ Exposure to Risks Arising from Physical Agents (Noise) (Standard No. Directive 2003/10/EC).
91. (2007). Vehicle Dynamics Test Methods—Part 3: General Conditions for Ride Comfort Tests of Passenger Cars (Standard No. ISO 15037-3).
92. Cășeriu, B.-M., Gabor, M.-R., Blaga, P., and Veres, C. (2024). Quantitative Analysis of Predictors of Acoustic Materials for Noise Reduction as Sustainable Strategies for Materials in the Automotive Industry. Appl. Sci., 14.10.3390/app142210400 ↗
93. (1981). Acoustics—Measurement of Noise Inside Motor Vehicles (Standard No. ISO 5128).
94. (2005). Acoustics—Measurement of Noise Inside Railbound Vehicles (Standard No. ISO 3381).
95. (2014). Uniform Provisions Concerning the Approval of Motor Vehicles with Regard to Their Sound Emissions (Standard No. UNECE Regulation No. 51).