Acoustic flight testing of rotorcraft often involves generating noise source hemispheres to gain an understanding about the aircraft's acoustic emissions. However, aerodynamically complex Urban Air Mobility and Future Vertical Lift vehicles may not maintain a steady aerodynamic state during flight, making source hemispheres measured using traditional linear arrays unreliable or difficult to interpret. To address this challenge, all emission angles need to be measured simultaneously. This has lead to the concept of the two dimensional 'snapshot' array layout. A mathematically defined microphone distribution was utilized to achieve uniform coverage on the source hemisphere. Within the chosen distribution, two lower microphone count distributions are embedded, allowing for a comparison of the effects of number of microphones. The array was deployed as part of a joint Army/NASA acoustic research flight test in July of 2024. Data were collected using an MD530F helicopter as the test vehicle

Houston, Mary, Stephenson, James, Pascioni, Kyle, Stutz, Colin

Research on Intake Sound Tuning Method by Valve Timing Modification for Enhance Sound Quality in V6 Outboard Engine

2024-32-00594/18/2025

This paper explores methods to enhance the sound quality of V6 outboard engines. Previous research in the boat and outboard engine domain has underscored the importance of enhancing sound quality. Specific preferences and desired directions for outboard engine sound quality have been identified. It’s been suggested that controlling intake sound and gear noise is important to achieving desired sound quality according to customer preferences. However, there are few examples of methods for achieving this. This study aims to develop methods for enhancing sound quality by emphasizing low-frequency sounds through intake sound. Initially, various methods were evaluated, and intake valve timing modification was chosen. Simple simulations confirmed that delaying valve timing for some cylinders may introduce characteristics that are not present in conventional cases. Subsequent 1D simulations identified optimal intake valve timing, balancing intake pressure characteristics and horsepower

Muramatsu, Hideta, Matsumoto, Taro, Naoe, Gaku, Kondo, Takashi

Impact of Ordinal Proximity of Frequency Components on the Auditory Perception of Engine Knocking

2024-32-00324/18/2025

This study examines the acoustic properties of engine-knocking sounds in gasoline engines, arising from misfires during spark ignition that negatively affect driving performance. The aim was to understand the frequency characteristics of acceleration sounds and their connection to the proximity of the order components. The study also explores “booming,” where two different frequencies of sounds occur simultaneously, potentially linked to the unpleasant nature of engine knocking. Using a sinusoidal model, we generated engine acceleration sound models with 5th-, 10th-, and 15th-order components, including engine knocking. Two types of sound stimuli were created: one with the original amplitude (OA) and one with a constant amplitude (CA) for each component order, emphasizing the order-component proximity in CA sounds. Aural experiments with 10 participants in an anechoic room using headphones and the MUSHRA method revealed an inverse relationship between OA and CA ratings as the component

Suzuki, Ryuhei, Ishimitsu, Shunsuke, Nitta, Misaki, Sakakibara, Mika, Hakozaki, Tomoyuki, Fujikawa, Satoshi, Iwata, Kiyoaki, Matsumoto, Mitsunori, Kikuchi, Masakazu

Challenges for Indian Road Traffic with Sound Alert Devices on Electric Vehicles

2024-26-02111/16/2024

Challenges for Indian Road Traffic with Sound Alert Devices on Electric Vehicles For safety towards pedestrians and other road-vehicles, sound alert systems (horns) have been in use since development of Automobiles. On the same line but with special purpose of preventing a Driver to sleep in a running vehicle, a Driver Monitoring System [DMS] is recently developed. For Electric Vehicles which are very quiet during starting and driving till 20 km/hr, Acoustic Vehicle Alert System (AVAS) is deployed in Europe and likely to be implemented in India soon. For all these Alert Devices, there are Standard Regulations across the world: ECE R-28 for Horns and ECE R-138 for AVAS. They, however, define only lower and upper dBA limits of the sound radiated by them. For DMS, no such regulation exists till today. With this, there has been a long time debate on what an optimal dBA level should be there, for all road-users as well as for vehicle- users inside the cabin. It would be adequate, on one

A, Milind Ambardekar

Methodology for jury evaluation and target setting for passenger vehicle operational sound quality

2024-26-02271/16/2024

In automotive market, with competitive car prices, build quality of a car will be a major distinguishing factor. Consumer's need for acoustic comfort has evolved from the removal of annoying noises to perceived sound quality. Operational sounds from electromechanical systems like sunroof system, window regulator, door lock system, HVAC etc. directly interact with users' senses. The perceived acoustics comfort of these sounds are direct indicators of vehicle character and can influence customer's buying decision. With the reduction in product development time and stringent cost constraints, a proper structured target setting methodology to benchmark & evaluate these operational sounds is crucial. In this paper, such a target setting methodology is proposed and discussed for operational sound quality evaluation. Electromechanical noises from various vehicles are measured using binaural head measurement system. Using Simultaneous Categorical Scaling method, jury evaluation is performed

Somasundharam, Sundaralingam, Manoj K, Mridul, RAJ, GAURAV, Mohammed, Riyazuddin, R, Prasath

Implementation Of Machine Learning In Acoustics Source Detection by Leveraging Synthetic Sound Data Generation Approach

2024-26-02131/16/2024

E-Mobility and Low Noise IC Engines has pushed product development teams to focus more on sound quality rather than just focus on reduced noise levels and legislative needs. Further more qualification of products from a sound quality perspective from an end of line testing requirement is also a major challenge. End of line (EOL) NVH testing is key evaluation criteria for product quality with respect to NVH and warranty. Currently for subsystem or component level evaluation, subjective assessment of the components is done by a person to segregate OK and NOK components. As human factor is included, the process becomes very subjective and time consuming. Components with different acceptance criteria will be present and it’s difficult to point out the root cause for NOK components. In this paper, implementation of machine learning is done for acoustic source detection at end of line testing. To improve the fault detection an automated intelligent tool has been developed for subjective to

Shukle, Srinidhi, Iyer, Ganesh, Faizan, Mohammed

A Detailed Study to Evaluate Sporty Sound Character of Passenger Cars

2024-26-02071/16/2024

Sound design is becoming increasingly important for vehicle manufacturers. ‘Sportiness’ of a car is one of the important criteria to consider while designing a car for passionate customers and those who love aggressive driving. Automobile manufacturers are identifying a typical sound for their cars as a ‘key product specification’ to attract particular market. This study focused on identifying frequency ranges and order content through a detailed study of subjective feelings based on physiological acoustics. A benchmark study of various different sport vehicles has been done to measure and record sound samples; these samples were further analysed based on sound quality parameters. Subjective evaluations were carried out by NVH experts to determine their concept of sportiness. Frequency ranges and order noise quantity were confirmed by correlations between subjective and objective evaluations under various customer drive patterns. Relations of the dominant exhaust firing order and its

Sadekar, Umesh Audumbar, Titave, Uttam, ZALAKI, NITIN, Naidu, Sudhakara, Vardhanan K, Aravindha Vishnu

Intelligent classification of automotive horn sound quality

2024-26-02041/16/2024

The primary function of an automotive horn is to alert pedestrians and other nearby vehicles to their safe passage on the road. Most of the human population is subjected to a certain amount of horn sound dosage daily. The study of automotive horns sound quality is equally important as their sound generation mechanism in high-end cars. The sound quality of automotive horns can be studied through subjective and objective test methods. In the present study, a subjective jury test and objective analysis using psychoacoustic parameters are conducted to classify car horn sound samples according to pleasantness. A total of twenty-two car horns, which consist of a disc and shell, are chosen for binaural sound recording. The recorded sound samples are used for subjective and objective analysis. Thirty members participated in the jury test, and a semantic differential method was selected to collect the user response. The Tukey range test is used to classify the subjective test data into groups

Mollah, Asfak, Mahanta, Tapan K., Balide, Venkatesham

Solving Whine Noise in Electric Vehicles: A Comprehensive Study Using Experimental and Multiphysics Techniques

2024-26-02221/16/2024

This paper examines one of the approaches used to identify the root causes of sound quality issues in vehicles, including the direct impact of psychoacoustics on the human experience. Specifically, the absence of masking effects provided by traditional combustion engines has made noise and vibration from electric drives significant factors in decision-making processes, with high-pitched tonal noise from electric motors causing annoyance and sound quality concerns for electrified propulsion systems. During vehicle testing at different speeds, a whining noise was observed, leading to an NVH test to locate the noise source. The noise is traced to the transmission by the dominating order of input reduction along with the contribution from the casing resonance. A multi-physics-based e-NVH analysis was performed, and the test data were correlated. By optimizing transmission error (T.E.) and implementing modifications to enhance the drivetrain design's stiffness, noise levels were reduced

Cheerla, Ganesh, Pulugundla, Krishna Chaitanya, Kolla, Kalyan Deepak, Sathyanarayana, P.V.V.

Characterize the Sound Field Generated from a Vehicle Horn by Pellicular Analysis

2025-01-00585/5/2023

To predict the sound field produced by a vehicle horn requires a good source representation of it in the full vehicle model. This paper investigates the characterization of a physical vehicle horn by an inverse method called pellicular analysis. To implement this method, firstly an acoustic testing is performed to measure the sound pressure radiated from the horn at a certain number of microphone locations in a free field environment. Based on the geometry of a virtual horn, the locations of each microphone and measured sound pressure data, pellicular analysis is adopted to recover a set of vibration pattern of the virtual horn. The virtual horn and the recovered vibration information are then incorporated in a full vehicle numerical model to simulate its exterior sound field. The validity of this approach is confirmed by comparing the prediction for a horn in a production vehicle to the corresponding physical test which is required to meet the Brazilian regulation CONTRAN 764/2018.

Yang, Wenlong, MELO, ANDRE

Methodology for Radiated Noise Refinement of Electrified Drivetrain Systems

2025-01-00985/5/2023

Electric drive units (EDU) of battery electric vehicles and electric drivetrain components of hybrid vehicles require significant development effort and planning to ensure that a refined NVH sound quality is achieved. New tools and methods are required to understand the NVH performance throughout the development process and to ensure that NVH risks can be quickly identified and mitigated within the correct EDU subsystems. This paper discusses the development of a methodology (EDSL – Electric Drive Sound Level) aimed at addressing this need. It also outlines how the EDSL tool can be used to address radiated noise issues and understand the NVH performance of the various subsystems within an electrified drivetrain component. The first use of the EDSL methodology is to characterize component-level radiated noise test results and compare the different mechanical and electrical noise sources to targets. The results from this are used to guide EDU development in the appropriate areas

Pruetz, Jeffrey E., Steffens, Christoph, Fu, Tongfang, Govindswamy, Kiran

Sound quality centered measurement technique over 40+ years: experiences and perspectives

2025-01-00735/5/2023

The author’s life work in acoustics and sound quality, though continuous over more than 40 years, has followed a number of parallel and nonparallel paths all involving measurement technologies and their evolution. The illustrated discussion begins at the Research and Development Division of Kimball International, Inc. (Jasper, Indiana) in 1976 with piano research using a Federal Scientific Ubiquitous analog real-time FFT analyzer and Chladni-plate-mode studies with fine sand and high-speed photography of sound board modes excited by various notes and damper pedal positions. It continues at Jaffe Acoustics, Inc., a concert-hall-specializing consultancy in Norwalk, CT, with early-reflection plotting using a parabolic microphone on an altazimuth angular-readout mounting and either photographing oscillograms, or running a high-speed paper chart printer, assembling “wheel plots” incremented every 10 degrees in azimuth and altitude to map reflection patterns. Involvement with binaural

Bray, Wade

Active noise control with head tracking system

2025-01-00125/5/2023

In active noise control, the control region size(zone of control) decreases as the frequency increases, so that even a small moving of the passenger's head causes the ear position to go out of the control region. In order to increase the size of the control region, many speakers and microphones are generally required, but it is difficult to apply it in a vehicle cabin due to space and cost constraints. In this study, we propose moving zone of quite actvie noise control technique. An 2D images based head tracking system captured by a camera to generate the passenger's head coordinates in real time with deep learning algorithm. In the controller, the control position is moved to the ear position using a multi-point virtual microphone algorithm according to the generated ear position. After that, the multi-point adaptive filter training system applies the optimal control filter to the current position and maintains the control performance. Through this study, it is possible to secure the

Oh, ChiSung

Localisation of Ultra-short Sound Emissions from Automotive Components by Using the Sound Field Scanning Method

2025-01-00925/5/2023

Design verification and quality control of automotive components require the analysis of the source location of ultra-short sound events, for instance the engaging event of an electromechanical clutch or the clicking noise of the aluminium frame of a passenger car seat under vibration. State-of-the-art acoustic cameras allow for a frame rate of about 100 acoustic images per second. Considering that most of the sound events introduced above can be far less than 10ms, an acoustic image generated at this rate resembles an hard-to-interpret overlay of multiple sources on the structure under test along with reflections from the surrounding test environment. This contribution introduces a novel method for visualizing impulse-like sound emissions from automotive components at 10x the frame rate of traditional acoustic cameras. A time resolution of less than 1ms eventually allows for the true localization of the initial and subsequent sound events as well as a clear separation of direct from

Rittenschober, Thomas

Active Control of Engine Order Noise for Heavy-duty Trucks: Using the Genetic Algorithm for the Optimization of Error Microphone Arrangement

2025-01-00135/5/2023

The arrangement of error microphones for a vehicle active noise control (ANC) system is no trivial work, especially for heavy-duty trucks due to the dilemma resulted from the large volume of the cab and the limited number of microphones accepted by most manufacturers in the auto industry. Most ANC developers resort to trial and error, which is not only a heavy workload given the amount of interested working conditions to be test, but also does not guarantee to yield the optimum noise cancellation performance. In this paper, the authors proposed an error microphone selection methodology using a genetic-algorithm (GA) -based mechanism. The target vehicle was a heavy-duty truck with a six-piston diesel engine, and two scenarios were particularly interested, i.e. driver & copilot and driver & one passenger sleeping on the berth. We first arranged eight microphones at different locations in the cab, five on the headrests, two on the B pillars and one at the head position of the sleeping

Wang PhD, Jian, Ling, Zihong, Zhang, Zhe, Cai, DeHua, lv, Xiao, Zhang, Ming, Gao, GuoRan

A study on active sound design and control method for vehicle interior hybrid noise to enhance sound quality

2025-01-00115/5/2023

With the current popularity of new energy vehicles and the continuous development of intelligent cabin technology, the demand for acoustic comfort within automotive cockpit is increasing. A multi-channel feedforward active sound design and control method was proposed to improve the sound quality of the hybrid broadband and narrowband noise inside the test vehicle. The method selectively designed the target amplitudes for broadband noise and narrowband noise in the vehicle to satisfy passengers comfort, mainly including the sound design phase and the control phase. During the sound design phase, objective sound quality parameter analysis was first conducted on the noise of the prototype vehicle, followed by an evaluation of the sound quality with semantic differential method. An active acoustic design strategy focusing on comfort, motivation sense and annoyance perception were proposed, including a formula for the target amplitude of adjustment order and sound pressure level. The sound

Liu, Xuexian, Xu, Wenxuan

Multi-Method Approach for car tailgate electric telescopic rod Noise: Detection, Characterization, and Prediction

2025-01-00385/5/2023

As the automotive industry moves towards greater intelligence, electric tailgate systems have seen widespread adoption, featuring remote control, obstacle detection, and intelligent opening functions that significantly enhance the user experience. The electric telescopic rod, as a key actuator, has drawn attention for its structural and transmission design. However, studies have shown that during actual operation, various noise issues arise with electric telescopic rods, affecting the sound quality and smoothness of the tailgate's opening and closing. This paper presents a noise detection and analysis study based on a bench test platform for a specific model of electric telescopic rod. Using a microphone to capture noise signals, three main types of noise were identified: high-frequency electromagnetic noise, low-frequency impact noise, and periodic structural noise. The study accurately detects high-frequency electromagnetic noise using wavelet packet energy feature extraction

fan, Sibei, wang, Siling, zhu, Zhehui, li, Lei, qin, Jiade, Meng, Dejian, pei, Kaikun

Design of the Evaluation Model of Acceleration Sound Quality of Automobile Based on MLP

2025-01-00375/5/2023

The acceleration vibe of a car's engine can be enhanced and a brand-specific auditory identity can be created via active sound design. Currently, experienced engineers were desperately required when the active sound design for car acceleration roar was processing, which consumed substantial time and human resources.Therefore, it is critical to conduct a research on the evaluation model for estimating car acceleration sound quality to improve sound design efficiency and reducing costs.1,000 acceleration roars samples of common cars were collected from the market in this paper, all of which could be commonly heard by the road. Nine psychoacoustic objective parameters, such as loudness, sharpness, and roughness, were calculated through Artemis Suite software, establishing a database for the sound quality of car acceleration sounds.Moreover, subjective evaluations of sound playback and objective data analysis were conducted to obtain the ratings of acceleration sounds.An evaluation and

xiong, Chenggang, Xie, Liping, Liu, Zhien, Shi, Weijie, Qian, Yushu

Comprehensive Analysis and Optimization of Door Closing Sound Quality of a Heavy Truck

2025-01-00665/5/2023

Based on the objective and subjective experiment and finite element analysis, the influencing factors on the door closing sound quality of a heavy-duty truck is analyzed and optimized. Results show that the loudness and sharpness can be reduced apparently by increasing stiffness and damping of the door. The sound quality can be enhanced by increasing the pressure release area, which can decrease the air resistance of dooring closing. By adding holes on the inner liner and changing the pressure release location, the dooring closing air resistance is reduced from 289 Pa to 181 Pa. In terms of the rebound sound, the sound level is positively relative to the door closing force. Increasing the protrusion height and decreasing the stiffness of the vibration absorber of the handle can improve the rebound sound quality. Optimizing the absorbers on both ends and adding damping material can decrease the loudness by 47.8%, reduce the cavity sound, dismiss the trembling and improve the compact

Wang, Jian, Zhang, Yongshen, Feng, Lei, Xie, Chenhao, Lin, Jiewei, Sun, Changchun

Research on the control strategy of active gear shifting sound quality in the vehicle

2025-01-00195/5/2023

The active sound synthesis system of electric vehicles plays an important role in improving the sound perception and transmission of working condition information inside the vehicle. Nowadays, the active sound synthesis system inside the vehicle has become standard in electric vehicles of major Major automobile manufacturing plants to meet the user groups' demand for driving and riding experience. Starting from the existing in-vehicle active sound synthesis algorithm, this paper designs a gear shift control strategy suitable for all working conditions. During acceleration, in order to achieve the gear shifting effect, the motor speed signal is obtained to bias the speed at the shift point. During deceleration, in order to prevent a sudden increase at the shift point, the speed of the deceleration condition is linearly interpolated to make the shifting process of the deceleration condition smoother. During acceleration after deceleration, in order to avoid the uneven sound jump at the

xilong, zhou, Liu, Zhien, Xie, Liping, Lu, Chihua, Yu, Shangbo, GAO, XIANG, yongsheng, wang

Development of Offline Simulation Software for Active Sound Design in Electric Vehicles

2025-01-00175/5/2023

With the increasing adoption of electric vehicles (EVs), Active Sound Design (ASD) has emerged as a crucial method to enhance both the sound quality and driving experience, addressing the lack of distinctive engine sounds present in internal combustion vehicles. This paper presents an ASD offline simulation software developed on the MATLAB platform to address these challenges. The software integrates a vehicle dynamics model with three key sound synthesis algorithms: order synthesis, pitch shifting, and granular synthesis, allowing for comprehensive control strategy development, real-time sound playback, and rapid adjustment. The software consists of several functional modules, including configuration, order generator, pitch shifting, and granular synthesis interfaces, which support user-friendly operation and flexible sound parameter adjustments. Users can simulate different driving conditions and evaluate the acoustic performance of the ASD system in real time. The system also allows

Qian, Yushu, Liu, Zhien, xiong, chenggang

Optimization of HEV Vehicle’s Engine Modulated Noise

2025-01-00845/5/2023

One 1.5L Miller-cycle turbocharged four cylinder gasoline hybrid engine is installed on a certain hybrid vehicle. When accelerating at low to medium speeds with a small throttle, there is a "da da" knocking noise inside the car, which seriously affects the overall sound quality of the vehicle. By analyzing the vibration and noise data of the engine, it was found that the frequency of the abnormal knocking sound is 200-1000Hz, which presents a half order characteristic in the time domain, that is, one knocking occurs when the engine crankshaft rotates twice. Through Hilbert demodulation analysis of the vibration data in the problem frequency range, it was found that the knocking noise was modulated in the frequency domain, with a modulation frequency of half of the crankshaft rotation frequency. By building a fully flexible multi-body dynamic model of a hybrid powertrain and inputting the engine's cylinder pressure excitation, the combustion excitation is coupled with mechanical

dan, Kong

Methodology for Sound Quality Metric Development

2025-01-00705/5/2023

Many individual technical descriptors exist to quantify and describe different kinds of acoustic phenomena. However, each only describes the technical aspects of a sound itself without considering any additional non-acoustic context. Human perception is greatly informed by this context. For example, humans have different expectations for the sound of an electric razor than they do for an internal combustion engine, despite both objects being able to be described by sound pressure level or a measure of roughness. No single technical descriptor alone works in all contexts as a gold standard that objectively determines whether a sound is “good.” Jury tests, however, are a great aid in gaining a measure of this context. When seeking to develop a meaningful quality index for the sounds of a device, it is often necessary to combine the perceptive information from the results of a jury test alongside one or more technical descriptors. The combination of perceptive data and technical

Thiede, Shane

The quality of vehicle horn sounds research and control

2025-01-00885/5/2023

Chinese consumers are very concerned about the quality of vehicle horn sounds, and the quality of vehicle horn sounds is very important in the overall NVH development process. This paper studies the sound quality of vehicle horns based on their working principles and characteristics, combined with the principles of vehicle vibration and noise control. It conducts research on the sound quality of vehicle horns from multiple dimensions, including vibration and noise excitation sources, transmission paths, and evaluation conditions. By analyzing the horn sound quality problems encountered in the development process of a certain domestic new energy vehicle, it proposes corresponding solutions. The results show that in addition to the common NVH phenomena of vehicle horns, the vibration and noise of vehicle horns can cause nonlinear phenomena in adjacent components, thereby producing abnormal noise. This study provides technical reference for nonlinear research and control of vehicle horn

li, 李. 治齐, zhou, changshui, Xie, Kai

Idle sound quality enhancement with optimizing exhaust manifold structure on a H8 engine

2022-01-07373/29/2022

Idle sound quality for motorcycle is critical to engineers to achieve. People would like to have a strong individualized sound in idle, but linear and smooth sound in driving condition. Since the idle fluctuation noise is based on the engine firing order, the exhaust manifold structure and the idle frequency by cylinder numbers, thus, compared to the two or three cylinders engines, eight or six cylinders engine are really hard to get a fluctuated tailpipe sound since the its higher firing frequency. However, the surrogate methodology can be applied on these engines. Based on the noise cancellation process in phase and amplitude in the exhaust manifold tube, engineers can manipulate the noise with several lower peaks compare to other higher peaks. In this scenario, people can feel the noise with big fluctuations although the smaller noise peaks are still there but in the masking. In this paper, a special case is presented by this methodology. In that case, an eight cylinders horizontal

Tan, Yang

Prediction and Optimization of Vehicle Interior Noise Sound Quality Based on XGBoost Algorithm

2022-01-03733/29/2022

In the subjective evaluation of noise, it is often necessary for experienced people to listen to a certain number of sound samples and score and evaluate it, which is time-consuming and labor-intensive, and it is easy to cause hearing fatigue and even lead to inaccurate evaluation results. In the past research on sound quality prediction models, multiple linear regression models, support vector machine models, neural network models, etc. were mostly used for prediction. In this paper, psychoacoustic objective parameters such as loudness, sharpness, roughness, speech intelligibility, and A-weighted sound pressure level are selected for objective evaluation and used as the input value of the prediction model. A grade scoring method was used to evaluate 68 samples of vehicle interior noise. Finally, the arithmetic average of the subjective scores of 20 people was calculated and used as the output value of the subsequent prediction model. Based on the XGBoost algorithm, a prediction model

OU, Jian, Liu, Jianqiu, ZHANG, Yong, YANG, E-chuan

Bus NVH refinement: A Journey towards Comfortable Future

2021-26-02729/22/2021

The future of bus transit in new millennium is promising. This optimism is based on an anticipated long-term slowdown in growth of suburbs and revitalization of central cities. It reflects and escalates the public concern with traffic congestion, sprawl and pollution. This calls for double the use of public transport to address above issues. It calls for changing the mind-set of society towards public transports like buses, coaches etc. This could happen if bus design ensures right comfort, safety & TCO by ensuring refined bus transport. Hence, it is responsibility of OEMs to provide the new generation buses and coaches, which will ensure the public demands of comforts in terms of NVH refinement. This paper covers the innovative approach used to convert the existing bus NVH refinement to next level as a short-term solution and with the intention of articulating NVH strategies for new generation bus development. This work explains combined experimental and simulation approach deployed

Doshi, Sohin, Taware, Girish, Kalsule, Dhanaji, Bijwe, Vilas, Naidu, Sudhakara

SOUND POWER ASSESSMENT, NOISE SOURCE IDENTIFICATION & DIRECTIVITY ANALYSIS OF COMPACTION MACHINES

2021-26-02819/22/2021

NVH has gained importance in the field of earth moving equipment due to the demand of quieter machines and stringent in-cab as well as exterior noise emission norms. Several parts of the world have adopted strict legislation on noise emission by earth moving equipment, but many countries have not adopted any regulations till date. This paper mainly focusses on helping governing bodies as well as machine manufacturers in adopting simple yet accurate testing method for compaction machine. The study consists of directivity analysis, noise source identification & noise source ranking and 4-point microphone position sound power evaluation method applied to compactors with wide range of engine power ratings. All the tests in 4-point method and directivity analysis were performed under stationary as well as dynamic conditions. Currently, several countries and vehicle manufacturers have adopted sound power evaluation of compactor exterior noise emission by 6-point method (as per ISO6393

Kandalkar, Milind Dadarao, bari, Jaykumar, Mole, Dhondiram, Harishchandra Walke, Nagesh

DESIGN AND ANALYSIS OF A MUFFLER FOR ENGINE EXHAUST NOISE AND HEAT REDUCTION

2021-28-01289/15/2021

Exhaust noise and heat from engines is one of component noise pollution to the environment. Exhaust systems are developed to attenuate noise meeting required db levels and sound quality, emissions based on environment norms. Mufflers are important part of engine system and commonly used in exhaust system to minimize sound transmissions caused by exhaust gases and reduction of heat. Attaching a muffler in the exhaust pipe is the most effective means of reducing noise and heat. The aim of our project is to design and analyse a muffler for engine exhaust noise reduction. The suitable design and development will help to reduce the noise level and heat level, but at the same time the performance of the engine should not be hampered by the backpressure caused by the muffler. In this analysis 3D models are constructed using Solid Works software before exporting to ANSYS FLUENT CFD software for analysis. At ANSYS/FLUENT, pressure conditions will be specified as the inlet and outlet boundary

Deepan Kumar, Sadhasivam, Praveenkumar, Nagarajan, S, Arulkumar, N, Boopalan, PRAVEENKUMAR, S

Identification of Low-Frequency/Low SNR Automobile Noise Sources

2021-01-10628/31/2021

This paper presents experimental investigations of determining and analyzing low-frequency, low-SNR (Signal to Noise Ratio) noise sources of an automobile by using a new technology known as Sound Viewer. Such a task is typically very difficult to do especially at low or even negative SNR. The underlying principles behind the Sound Viewer technology consists of a passive SODAR (Sonic Detection And Ranging) and HELS (Helmholtz Equation Least Squares) method. The former enables one to determine the precise locations of multiple sound sources in 3D space simultaneously over the entire frequency range consistent with a measurement microphone in non-ideal environment, where there are random background noise and unknown interfering signals. The latter enables one to reconstruct all acoustic quantities such as the acoustic pressure, acoustic intensity, time-averaged acoustic power, radiation patterns, etc. By combining a passive SODAR and modified HELS methods, engineers will be able to

Lu, Yazhong, Wu, Sean, Yuan, Zeyu, He, Wen, Li, Zhaoting, Li, Huijun

Analyses of Low-Frequency Motorcycle Noise Under Both Steady-State and Transient Operating Conditions

2021-01-11088/31/2021

This paper presents experimental investigations of diagnosing and analyzing the low-frequency, low- SNR (Signal to Noise Ratio) noise sources of three motorcycles using a hybrid technology that consists of a passive SODAR (Sonic Detection And Ranging) and modified HELS (Helmholtz Equation Least Squares) methods. The former enables one to determine the precise locations of multiple sound sources in 3D space simultaneously over the entire frequency range that is consistent with a measurement microphone in non-ideal environment, where there are random background noise and unknown interfering signals. The latter enables one to reconstruct all acoustic quantities such as the acoustic pressure, acoustic intensity, time-averaged acoustic power, radiation patterns, and sound transmission paths through arbitrarily shaped vibrating structures. By combining a passive SODAR and modified HELS methods, engineers are able to reveal the low-frequency noise sources that cannot be accomplished by using

Lu, Yazhong, Wu, Sean, Yuan, Zeyu, He, Wen, li, Zhaoting, Li, Huijun

Process for Optimizing Acoustic Vehicle Alert System (AVAS) for FMVSS-141 and Interior Sound Quality

2021-01-11218/31/2021

The automotive industry is shifting towards the development of hybrid electric and electric vehicles. These vehicles primarily use electric motors for propulsion and can be significantly quieter to pedestrians than traditional ICE (internal combustion engine) vehicles. The NFB (National Federation of the Blind) and others highlighted a concern with these quiet vehicles related to pedestrian safety and the inability to use historical sound signatures to detect a moving vehicle. To address this concern, NHTSA created FMVSS 141, which identifies minimum external sound requirements for hybrid and electric vehicles during stationary conditions and in motion up to 30kph. [1] OEMs are now required to implement Acoustic Vehicle Alerting Systems (AVAS) that use external speakers to generate additional noise to meet the regulation. These noises are intended to raise the exterior sound level of the vehicles, while still attempting to maintain a quiet, pleasant experience for the passengers in the

Doxen, Dominic, Zorn, Tim

Novel Engine Sound Quality Evaluation Method in Bench Testing

2021-01-10298/31/2021

A lot of engine sound quality issue can be classified as some specific words, such as “Rattle, Knocking, Modulation, Loud, Whistles” and etc. Engineers were trying to quantify this phenomenon with objective data. In this paper, we would like to propose a novel method that separates the engine sound quality into five different objective parameters, which covers engine noise level, whine or whistling, clatter - tick phenomenon and roughness. Based on the new method, the engine sound quality can be mapped into a final sound quality matrix - ESQM (Engine Sound Quality Matrix) to compare by the total number or by the contributors individually.

Tan, Yang, Yang, Jingling

Target Development for Hybrid and Electric Vehicle Powertrain Sound Design

2021-01-10178/31/2021

Relative to Combustion Engine vehicles, electric powertrains are a blank canvas for sound. There are an increasing number of applications where sound is added to enhance the driving experience and increase pedestrian safety. In Hybrid vehicles, the combustion engine sound is not always present and must properly blend in with any additional sound added to the vehicle. Vehicle manufacturers have an opportunity to reinforce their brand identity through the addition of the perfect, target sound. Each brand, market segment, and powertrain require unique sounds. In addition, shuttle or ride sharing applications highlight the need for added sound during other scenarios to reinforce the brand sound. Traditional sound quality measurements and preference testing are very limited in defining the perfect sound due to the subjective nature of sound design. This paper describes an improvement over prior sound quality process development through the incorporation of several subjective input tools

Trumpy, David, Krueger, Sebastian, Tousignant, Todd

Prediction and Validation of Cab Noise in Agricultural Equipment

2021-01-10708/31/2021

To improve overall customer experience, it is imperative to minimize the noise levels inside agricultural equipment cab. Up-front prediction of acoustic performance in product development is critical to implement the noise control strategies optimally. This paper discusses the methodology used for virtual modeling of a cab on agricultural equipment for prediction of interior noise. The Statistical Energy Analysis (SEA) approach is suitable to predict high frequency interior noise and sound quality parameters such as articulation index and loudness. The cab SEA model is developed using a commercial software. The structural and acoustic excitations are measured through physical testing in various operating conditions. The interior noise levels predicted by the virtual model are compared with the operator ear noise levels measured in the test unit. The resultant SPL spectrum from SEA correlates well with the test. This model is used to optimize the noise control treatments and improve the

Mandke, Devendra, Fapal, Anand, Pawar, Sachin, Cone, Kerry

Numerical and Experimental Investigation and Refinement of Automotive HVAC Flow Induced Noise

2021-01-10568/31/2021

Automotive heating ventilating and air conditioning (HVAC) noise is a very big concern for original equipment manufacturers (OEM) and suppliers. It turns out to be more challenging as the demand for acoustic comfort is increasing day by day. Many times an existing HVAC with some minor changes (mostly the vehicle fitment points) is proposed for face-lift vehicle but the performance expectation is far beyond the existing one due to market demand. One of the critical requirements is enhanced sound quality. To achieve that either experimental testing or numerical simulation is adopted. In either of these cases, it ends up with high number of experiments or increased simulation cost due to aero-acoustic simulation. Hence a combined approach is followed in order to investigate and improve the noise sources of an existing HVAC. The present paper describes this approach in details by doing numerical flow simulation followed by experimental investigation. HVAC was modeled using computational

Sen, Somnath

Root-Cause Analysis, and Improvement of a Port Fuel Injected V6 Vehicle to Achieve Best-In-Class Sound Quality

2021-01-10418/31/2021

This paper will communicate an in-depth investigation uncovering contributing factors defining the desired and undesired acoustic signature of a V6 Vehicle. A transfer path analysis tool is exercised to rank improvement opportunities. These results are used to drive design improvements with the goal of achieving best-in-class sound quality when executed as a system. A cohesive powertrain-vehicle-level acoustic improvement package is executed, improving air induction, intake manifold, both structure and air-core, exhaust-radiated and under-hood-acoustic encapsulation. The acoustic package was validated by jury testing to provide significant refinement enhancement improving predicted 3rd party scores.

Brosseau, Justin, Yuan, Wei, Singh, Vinod, Orzechowski, Jeff

Development of a Process to Predict Whole Vehicle Aeroacoustic Interior Noise

2021-01-10478/31/2021

Quality and refinement are of paramount importance for luxury vehicles. The rapid electrification of the automotive industry has increased the contribution of aeroacoustics to the consumer perception of sound quality. The ability to predict whole vehicle aeroacoustic interior noise is essential in the development of vehicles with an extraordinary acoustic environment. This publication summarises the development of a process to combine lattice Boltzmann computational fluid dynamics simulations, with a whole vehicle statistical energy analysis model, to predict the aeroacoustic contribution from all relevant sources and paths. The ability to quantify the relative contribution of glazing panels and path modifications was also investigated. The whole vehicle aeroacoustic interior noise predictions developed, were found to be within 2dB(A) of comparable test vehicle wind tunnel measurements, across a broad frequency range (250-5000Hz). The ability to determine panel contributions and

West, Benjamin, Daniels, Holly, Venor, Joseph, Martin, Simon

Simulation Diagnostics Approach for Identification, Ranking and Optimization of Electric Motor Design Parameters for Optimal NVH Performance

2021-01-10798/31/2021

With increasing efforts towards rapid electrification of powertrains, NVH engineers face new set of challenges. Elimination of the IC engines drastically reduces powertrain borne noise levels but unmasks other existing noises like wind, road, ancillary devices, and squeak & rattle. In addition, the new tonal sounds from electro-mechanical drive systems makes the noise more annoying even though it is lesser quantitatively. In summary, the electrification of powertrains has shifted powertrain NVH development from overall level to sound quality with different targets requiring several electro-mechanical solutions with innovative simulation, testing, and optimization approaches. The purpose of the paper is to present an approach to detect, quantify, and optimize the structure-borne radiated noise of an electric motor due to electromagnetic forces or maxwell pressure exerted by magnetic effects in electric motor. The Maxwell electromagnetic excitations are computed and applied on the stator

Parmar, Azan, Miskin, Atul, Maheswar Rao, Uma, Reddy, Hari Krishna

Sound Quality Evaluation Method for Engine Combustion Noise in an Engine Acoustic Test Cell

2021-01-06744/6/2021

In order to efficiently enhance engine sound quality under acceleration, the authors have developed an evaluation method for primary judgment of the sound quality of engine combustion noise at the stage of advanced engine development before the prototype vehicle is built. This method is an application of an existing method for evaluating the sound quality of engine combustion noise in vehicle interiors to the evaluation of noise and vibration at an engine acoustic test bench. In this method, it is necessary to consider the air-borne and the structure-borne components separately. The analysis procedure for the air-borne component is as follows. First, the sound pressure at a point 1 m away from the engine and the in-cylinder pressure of each cylinder are measured simultaneously in a semi-anechoic engine dynamometer test chamber. Next, the signal correlated with engine combustion is extracted from the measured sound pressure using the time domain combustion noise separation method. Then

Torii, Kenji, Noumura, Kousuke, Miyazawa, Masaya, Kondo, Takashi

Analysis and Optimization of the Idle Sound Quality Based on RBF Prediction Model

2021-01-06604/6/2021

Idle sound quality of four-cylinder DI gasoline engine is predicted and optimized. The objective parameters of psychoacoustics such as loudness, roughness, sharpness, tonality, fluctuation, and interference are selected for objective evaluation. The numerical valuation method is used to evaluate the 21 engine noise samples at the idle condition. The Kriging, RBF, and RSM prediction methods are respectively used to establish the subjective and objective regression model. The prediction results are compared with the actual subjective evaluation results and show that the RBF method has the highest consistency with the correlation coefficient is 0.912. The sensitivity model of objective evaluation parameters of sound quality based on RBF is established. The contribution of objective evaluation parameters that affect the idling sound quality is calculated quantitatively. The contribution of sharpness to the sound quality of the gasoline engine is the largest (39.6%), followed by loudness

Maorong, Yuan, Jingsi, Wei, Rong, Bi

Medium-Sized Helicopter Noise Abatement Flight Test

F-0076-2020-16497

10/5/2020

An extensive flight test campaign was recently completed, which aims to reduce the operational noise generated by helicopters in an effort to improve community acceptance. Using a ground-based microphone array, acoustic measurements were acquired on helicopters in the medium-sized vehicle weight class over a number of flight conditions including steady level flight, steady descents, and approaches. While data were collected across four helicopters, the Leonardo AW139 and Sikorsky S-76D will be the focus of this paper. Source noise hemispheres are computed for the steady test points, but the ground noise contours measured during approach conditions cover only a small portion of the area impacted by noise because of practical constraints on the size of the deployed array. Thus, the Noise Informed Community Environment Operations Planning System (NICEOPS) in conjunction with the flight test data was used to estimate how changes in the approach procedures impact noise exposure over a

Pascioni, Kyle, Watts, Michael, Stephenson, James, Greenwood, Eric, Smith, Charles