Handbook of Vibroacoustics, Noise and Harshness

The urban environment is characterized by diverse noise sources, which include various modes of transport, industrial activities, household disturbances, and recreational activities. This collective soundscape in an urban setting is recognized as an emerging environmental concern. Particularly, transportation noise often exceeds the recommended guidelines established by the World Health Organization (WHO), and individuals exposed to it experience detrimental health effects. These ill effects include sleep disturbance, annoyance, hearing problems, cardiovascular diseases, and mental illness. Furthermore, these detrimental effects extend to the economic well-being of the public and the government. The issue of railway noise has gained attention due to the growing demand for rail transport and the expansion of railway networks. Unplanned urbanization has led to the settlement of migrants from rural areas close to railway lines, exposing them to continuous noise pollution and adversely affecting their health and well-being. Therefore, it is necessary to consider the characteristics and influences of individual sources to understand railway noise as a whole comprehensively. Various aspects of railway noise including its sources, measurement methods, characteristics of noise transmission pathways, receiver’s perception, mapping of railway noise, and control measures are documented sequentially. Additionally, the potential research areas encompassing railway noise evaluation, modelling, policy regulations, impact of meteorological conditions, design of noise mitigation barriers, and situational factors related to buildings are also presented.

The chapter extensively reviews the impact of vegetation on urban noise mitigation and control. It analyzes various factors, including type, density, height, and width, affecting the attenuation provided by vegetation, and it advocates for the use of vertical green wall systems, green roofs, and vegetative noise barriers to attenuate and control traffic noise. These green infrastructure elements not only enhance esthetics but also contribute to noise reduction. Additionally, it presents an evaluation of sound absorption characteristics for commonly available vegetative species in reverberation chambers. Overall, integrating vegetation into urban design is vital for creating a quieter, healthier, and more sustainable environment.

The knowledge of how acoustic waves propagate from one acoustic medium to another, and what happens to the acoustic waves when they encounter obstacles to their propagation, is a prerequisite for any NVH engineer and researcher. Acoustic waves propagate unperturbed in a uniform homogenous medium. Acoustic medium changes whenever there is a change in bulk modulus or mass density or both of the medium. The change in acoustic medium offers resistance to wave propagation and this resistance is quantified in terms of the acoustic impedance of the medium. The wave as a result undergoes reflection, transmission, and absorption at the medium boundaries. The phenomena of reflection, absorption, and transmission has been described in detail in this chapter. Important relationships among reflection, absorption, and transmission coefficients have been derived, and the knowledge gained will form a solid foundation for noise control engineers and researchers.

Since its first publication in 1971 of ISO/R 1996:1971 on Acoustics Assessment of Noise with Respect to Community Response, the International Organization for Standardization (ISO) has developed and published a range of standards for environmental noise assessment. The main ISO 1996 series of standards on Description, Measurement and Assessment of Environmental Noise has been developed in phases. Since then, a wide range of other standards have been added, covering different aspects such as attenuation of sound during propagation outdoors, quality assurance of software for the calculation of sound outdoors, soundscapes, and noise from shooting ranges, airports, and industrial plants.This chapter provides an overview of ISO standards related to environmental noise assessment. It also describes the historical development of the ISO 1996 series of standards. Current developments, including their status, are described.Excluded from this chapter are the ISO standards concerning noise at work, indoor noise assessment, and assessment of individual source emission and of noise barriers. However, a reference to all standards managed by ISO Technical Committee 43 Sub Committee 1 Acoustics – Noise is included in this chapter. Also excluded are other international standards such as ISEE blasting and national or regional standards as produced by BSI, DIN, AFNOR, etc. or in European Union-funded projects such as Harmonoise/Imagine and CNOSSOS-EU.

The present chapter deals with the study of the most ignored pollutant of modern times, i.e., “Traffic noise.” Noise from the transportation system in general and road traffic, in particular, presents itself as a xenobiotic substance that can result in or pose a serious threat to public health. Traffic noise is more severe and widespread than ever before and would continue to grow in magnitude and severity due to the rapid rate of urbanization, population growth, and the ever-increasing usage of mobile sources of noise. The harmful health effects of traffic noise are numerous, ubiquitous, lasting, and socially and medically significant.Environmental noise including traffic noise and its associated health effects has failed to garner any attention from the concerned governmental authorities in the developing countries including India. This has led to a dearth of available knowledge regarding traffic noise exposure and health impacts in the context of developing countries. However, the research studies from the developed countries have provided ample evidence that the nonauditory effects are equally significant. The reason for assigning high importance to nonauditory effects is because such effects do not require the cognitive perception of the noise by the exposed population and that the effects can occur without any notice of significant changes in the physiological systems. The traffic environment in developed countries being homogeneous varies from the traffic scenario of developing countries like India. The risks associated with traffic noise exposure can differ both in magnitude and severity due to the prevalent heterogeneous traffic conditions. It was realized that the limited literature available under the context of developing countries mostly dealt with the auditory outcomes. To augment this deficiency, this chapter presents the effects of road traffic noise on the nonauditory outcomes like cardiovascular outcomes, metabolic disorders, cancers, sleep disturbances, etc., based on the studies carried out in developed countries.

This chapter highlights the significance of addressing the problem of growing traffic noise pollution and the use of traffic noise assessment and modelling in this much-needed endeavor. High traffic noise levels have adverse health effects like cardiovascular disorders, speech interference, sleep disturbance, etc. The traffic noise measurements are done for environmental studies, design of buildings, and barrier design, to decide compensation cases in case of litigation by residents and protecting resident population from high traffic noise levels by the pollution control boards and regulatory agencies. The different sources of road traffic noise and contributors to individual vehicle noise have been discussed. The vehicle noise sources include propulsion noise, tire-road interaction noise, aerodynamic noise, gearbox noise, brake noise, and rattle noise. The fundamentals related to traffic noise modelling like traffic noise descriptors, parameters, standard traffic noise measuring equipment, and procedure have been described. A brief description of the statistical pass-by test for vehicle noise has been given. A classification of the diverse traffic noise models (deterministic, statistical, machine learning based, country specific, static, and dynamic) has been presented. Some of the latest traffic noise models like the CNOSSOS-EU model have been discussed. A simple selection criterion to choose a relevant modelling approach based on the regional concerns, geographical requirements, constraints, and availability of tools and skills has been outlined.

The accurate and reliable operation of medical devices is of utmost importance, as any reduction in their quality may lead to fatal consequences or cause injury. In this context, Electromagnetic Interference (EMI) and Signal Integrity (SI) are critical factors that must be taken into consideration during the design process of medical devices. This chapter discusses the noise source in printed circuit boards (PCBs), which can adversely affect the performance of medical devices. The chapter also provides insights on how to reduce the impact of noise, including the use of a clear return path toward the ground plane and a hybrid configuration for high-frequency signals. By understanding the physical behavior of SI problems from an EM perspective, medical device designers can address these issues and ensure the reliable operation of medical devices.

The chapter describes multi-criteria decision-making (MCDM) models in the selection of optimal noise action plans. The study utilizes the Fuzzy TOPSIS (Technique for Order Preference by Similarity to an Ideal Solution) decision model and PROMETHEE II (Preference ranking organization method for enrichment evaluation) in determination of the ranking order of the various alternatives for aircraft noise control in comparison to the various criteria is considered. The application of both the approach can be instrumental in prioritizing the selection of noise action plans utilizing the fuzzy linguistic variables when precise values are not easily obtainable. It is envisaged that both the approach can find an immense utility for the selection of noise action plans for the task force committees responsible for project noise evaluation and control. The uncertainty in developed decision-making model can be reduced by including the precise data of ratings of alternatives w.r.t each criteria or by inviting the opinion of various field experts.

The chapter reviews the various approaches carried out for noise modeling and mapping in recent times. Noise modeling and mapping is a very vital tool for understanding and evaluating the noise scenario in urban environments and has been used aggressively in European continents to promote sustainable and quieter environment. In the Indian scenario, this exercise has been now widely used in order to understand the noise scenario and devise suitable mitigation strategies for noise pollution prevention and control. However, the major bottleneck arises in terms of having a countrywide validated noise model. The present chapter presents a case study of noise mapping and simulation of the control strategies on a specialized commercially available noise mapping software package. The chapter is very helpful for planning and devising appropriate control measures for reducing the noise exposure to the community and promotion of quieter environment in urban scenario.

This study demonstrates the lockdown affected the ambient auditory environment of Nagpur city, India. It reveals the noise scenario for the lockdown and post-lockdown phases of the pandemic. The condition during the COVID-19 epidemic was extremely negative and undesirable for traditional noise monitoring. The study selected a famous alternate approach to noise monitoring. Crowdsourcing was used to collect noise data from over 67 places throughout the city using the Android smartphone application “Noise Tracker.” The data analysis demonstrates a considerable reduction in ambient noise levels during the lockdown time, with the noise level at maximum places ranging within the safer side. It was observed that ambient noise levels were reduced by an average of 7.04 dB during the day (06:00 am to 10:00 pm) and 4.67 dB at night (10:00 pm to 06:00 am). The study used noise maps to illustrate lockdown and post-lockdown noise scenarios. The total study found a considerable drop in ambient noise levels during lockdown conditions, which can be attributed to reduced road, rail, and aviation traffic movements. The study also verifies the crowdsourcing strategy and the usage of smartphones for environmental science experiments. Such a study was never undertaken in Nagpur, where citizens contributed to the research.

The continuous expansion of urbanization and rapid technological progress propel our societies forward, but they also give rise to an escalating concern: environmental noise pollution. This pervasive issue has profound implications for human well-being. Currently, the intensifying need and aspiration for noise control have escalated owing to the expansion of highways, enhancements in existing road networks and traffic volumes, and the proliferation of residential communities and other noise-sensitive developments. A frequently used approach to noise control involves managing the transmission path, which in certain situations may represent the most viable solution. Noise barriers or acoustic enclosures and structural modifications (such as building design alterations) are classified as path-control measures, where the propagation path of noise is either intercepted or absorbed, or a combination of both. Interception involves phenomena like reflection and diffraction, while certain materials also facilitate sound absorption. The chapter focuses on the concept of controlling the transmission path of noise pollution.

The chapter discusses the various traffic noise prediction models developed in India with an objective of traffic noise predictions and forecasting. These models had been developed based on various techniques such as Multiple Linear regression approach, Artificial Neural Networks, calibration of foreign models such as RLS90, FHWA, etc. and based on machine learning techniques. However, there is a need for a validated and reliable model suitable for carrying out the Environmental Impact Assessment (EIA) studies w.r.t noise that is also recognized by the state/central pollution control agency integrated with a GIS interface and suitable for devising the noise control measures. The study also discusses the various attributes of an efficacious model that can be indispensable for urban planning in order to optimize the road layouts and minimize noise impacts on residential and silence zone areas. The major point of debate among the scientific fraternity arises in developing either a source-specific model, or a regression-based model or using the advanced time-series techniques for traffic noise modeling.

Noise pollution is a growing concern in urban environments, significantly impacting residents’ health and well-being. Extensive research has highlighted the detrimental effects of exposure to higher noise levels for a longer period of time, linking it to cardiovascular issues, sleep disturbances, and increased stress (Hänninen et al. 2014). Noise pollution in urban areas arises from different sources such as transportation which mainly include road traffic, railways, and aircraft, various industrial activities, and different recreational events (Bala and Verma 2020). The WHO Environmental Noise Guidelines for the European Region highlight that the main contributors to urban noise pollution are road traffic, followed by railway and aircraft noise, which collectively impact millions of people (Jarosińska et al. 2018). India has seen a dramatic rise in traffic over recent decades, with a significant surge in the number of motor vehicles. This increase has resulted in severe congestion and pollution in urban areas. Factors such as rising personal incomes and the growing desire for enhanced mobility and convenience have fueled this growth (Mehta 2011). The resulting surge in traffic imposes tremendous pressure on the existing infrastructure, leading to frequent traffic jams and prolonged travel times. Additionally, the increased traffic has significantly elevated noise levels, contributing to heightened annoyance and stress among urban communities​, leading to widespread annoyance among residents (Schreckenberg et al. 2010). Julie Méline et al. (2013) reported that individuals exposed to higher levels of road traffic noise experienced greater levels of annoyance, even after considering socioeconomic factors (Méline et al. 2013). Noise annoyance characterized by negative reactions such as displeasure, disturbance, and stress can escalate into severe health issues like anxiety, depression, and cardiovascular problems (Gilani and Mir 2021). Persistent noise disturbance disrupts daily activities and sleep, compounding stress. These disturbances often result in chronic stress responses, affecting both mental and physical health over time. Studies indicate that individuals exposed to higher traffic noise levels report greater annoyance and are more likely to develop health issues related to prolonged stress and disturbed sleep patterns (Kroesen et al. 2008; Emin and Uslu 2015).

Vibration measurement technology is less than 100 years old. It started with sensing earthquakes and aerospace applications. In machines, vibration measurements are important from their condition monitoring point of view and also for controlling their vibrations. There are both contact and noncontact types of vibration measuring systems available. Basically, the measuring system consists of a transducer, a signal conditioner, and a display (analog or digital) to display the vibration level. Vibration transducers giving signal output proportional to vibration acceleration, velocity, or displacement are used. The working of accelerometers, velometer (and laser-based instruments), different types of proximity probes, and LVDT is described. They all have their advantages and limitations and are to be selected as per the application. It is also useful to get a frequency spectrum of the vibration signal giving information about the frequency contents of the vibrating object. This information is obtained with the help of FFT analyzers and is required for monitoring the condition of machines as well as for vibration control work. Theory behind these analyzers and details of facilities provided in them have been covered. Finally, instrumentation for modal testing to obtain natural frequencies of structures is described.

The present chapter introduces vibrations, establishing a robust basis for comprehending this significant facet of physics and engineering. This chapter examines the phenomenon of vibrations in various natural and artificial systems to ascertain its underlying causes. The following part elucidates pivotal historical occurrences in the realm of vibrations, facilitating our comprehension of these phenomena. This chapter’s primary emphasis is the mathematical modelling of systems with a single degree of freedom. The study aims to investigate the complexities associated with these systems, including both damping and non-damping scenarios. This study’s objective is to comprehensively examine harmonic stimulation’s impact on vibrating systems. The primary aim of this study is to elucidate the intricate relationship between external factors and the corresponding reactions of a given system. This chapter encompasses many scholarly materials for anyone interested in furthering their knowledge. This research analyzes vibrating systems with several degrees of freedom, exhibit continuous (distributed) behavior, and display nonlinearity. These disciplines provide a captivating insight into the realm of vibrational dynamics. This chapter establishes a fundamental framework for comprehending vibrations and their many scientific and engineering utilizations.

There is tremendous increase in the number of line frequency powered electronic equipment since last five decades. About 60–70% of electric power is processed through electronic power converters in the rapid expansion of industrial, commercial, transport, residential, and military, and will eventually be 100% by next decade. The technology of power converter has brought revolution in the utility scenarios globally. The use of these power processors is not limited to automation and control but has impact on communication and information technology. All active and passive power electronic equipment employed to process power electronically basically generates unwanted electrical signals, in the form of electromagnetic noise called pollution. This electromagnetic pollution leads to performance degradation and electromagnetic interference (EMI) with other equipment or systems. Undoubtedly, this EMI would ever increase, unless EMC standards are enforced mandatory to follow major compatibility limits. The first part of the chapter reviews the mechanisms that lead to the generation of EMI signals through power electronic equipment and introduces the various noise types along with their propagation mechanisms. Also, the problems caused by the various noise types are presented. An overview of the standards will follow. Further, a brief discussion about various noise mitigation techniques and their evaluation has been presented with emphasis on line harmonics reduction.

This study investigates the vibrational behavior of palm leaflets submerged under varying conditions in water, focusing on flexible cantilever beams made from a coke can material. The beams, with dimensions including a thickness of 0.102 mm, a density of 850 kg/m3, and a Young’s modulus of 5 GPa, were subjected to controlled sinusoidal motion using a shaker. Laser Doppler vibrometry was employed to analyze the vibration characteristics. The experiments were conducted within a 150-l fluid tank to minimize wall effects, ensuring accurate flow dynamics near the oscillating structure. Standard room temperature conditions prevailed, with assumed fluid properties of density and dynamic viscosity. The results demonstrate that increasing the submerged length of the beam in water significantly reduced both its first mode frequency and quality factor. These changes primarily stemmed from fluid loading effects and heightened damping within the submerged environment. The surrounding fluid added mass and viscous resistance to the beam, altering its natural frequency and decreasing its ability to sustain high-quality vibrations. This research underscores the pivotal role of fluid-structure interaction in influencing the vibrational dynamics of submerged cantilever beams, highlighting implications for various engineering applications where such interactions are critical.

This chapter provides a comprehensive study about the aircraft engine condition monitoring for predictive maintenance. Aircraft engines are among the most critical components of an aircraft, and their reliable performance is paramount to flight safety and operational efficiency. To ensure the continued airworthiness of these engines, maintenance practices have evolved from reactive to proactive approaches, with predictive maintenance emerging as a crucial strategy. This chapter explores the concept of aircraft engine condition monitoring for predictive maintenance, covering the key principles, technologies, methodologies, challenges, and benefits associated with this approach. It also provides aircraft noise and vibration measurement principle and its suppression technique. Aircraft condition monitoring using noise and vibration signals is a proactive approach to maintenance that enables early detection of faults, reduces downtime, enhances safety, and optimizes the operational efficiency of aircraft systems.

The chapter describes the various forms of periodic structures, i.e., sonic crystal, metamaterials, locally resonant structures, etc. Since the last few decades, periodic structures have been widely used by researchers as wave attenuators for particular frequencies. As the name suggests, periodic structures are those in which an object is embedded with a regular interval into another material. The shape of the object, type of periodicity, density ratio, periodic constant, etc., may vary according to the application. This chapter involves the various applications of periodic structures and acoustic panels when these are subjected to audible waves and elastic waves. The chapter also discusses the various numerical techniques, i.e., plane wave expansion method, the Webster horn method, finite element method, and analytical methods to compute the sound attenuation properties of periodic structures and panels. The chapter discusses the combined behavior of sonic crystal with acoustic panels. It includes various recent research findings and the future scope of periodic structures and panels.

The acoustic properties of the material are defined by the reflection coefficient, absorption coefficient, and transmission coefficient. The experimental setup follows the ASTM-2611 standard of four-microphone impedance tubes with two load boundary conditions to measure these coefficients. The setup consists of four microphones around a brass tube with the speaker at one end and termination at the other. Raw data from the four microphones is obtained through a Virtual Instrument (VI) program developed in LabView. The mathematical equations involved in estimating acoustical properties is solved in MATLAB 2019a. The reflection and absorption coefficient data of ephony fibbrette of 15 mm thickness are compared with the data provided by an accredited laboratory. This material is used in the auditorium, and theaters, for hearing comfort. Further, two new samples of ephony fibbrette along with wood fiber cement and damper have been analyzed.

This chapter presents a modal analysis of the electric motor automotive component. Using the finite element approach, the frequency responses for the electric motor’s rotor component were calculated. The results of the modal analysis of the electric motor’s overall deformation frequency are compared between the stator and rotor parts. The electric motor components are designed using CATIA V5, which also made it simpler to assemble complex pieces. Using ANSA, which turns the domain into a mesh and immediately shows the failure part, the electric motor is refuted. Modal vibrations are calculated using a numerical method. To prevent resonance, rigid body and natural frequencies are computed and shown in various modes. The system is investigated using the ANSYS finite element (FE) code.

The modern era of urbanization and technological advancements has witnessed a substantial increase in noise levels, making it paramount to understand and innovate in the field of sound insulation. This chapter explores the critical and continually evolving field of sound insulation, addressing major public health concerns associated with noise pollution. It highlights the prevalence of noise pollution in urban environments and its diverse detrimental health effects, such as hearing loss, stress, cardiovascular diseases, and cognitive impairment. Consequently, the discussion delves into noise control strategies, distinguishing between active and passive noise control mechanisms. Active noise control involves using electronic means to cancel out sound waves, while passive noise control relies on materials and designs to absorb or reflect sound energy. Moreover, a significant section focuses on sound insulation materials, which are essential for passive noise control, as they reflect sound waves. It also elaborates on these materials by detailing their performance metrics, typical sound transmission loss (STL) curve, factors affecting STL, and their effectiveness in mitigating noise pollution. Additionally, it discusses experimental methods for measuring STL and predictive models for assessing STL in materials. A comprehensive review of commercially available sound insulation materials introduces traditional materials alongside recent advancements such as metamaterials, perforated panels, and polymer composites. Furthermore, the potential of using recycled or waste-derived materials in sound insulation is thoroughly discussed, spotlighting their practical applications and future research prospects. In conclusion, the chapter reviews sound insulators and their integral role in noise control strategies, thereby contributing to improvements in public health. Through a detailed review of materials, strategies, and experimental methods, this chapter offers valuable insights into the current state and future directions of sound insulation technology.

Sound pressure is the measurand of acoustic quantity. Acoustic instruments are used to determine the quantity value of sound pressure. Calibration of the instrument is required to ensure the accuracy of the measurement results. The metrological traceability linked the instrument measurement result to the primary standard through an unbroken calibration chain by the secondary lab to the National Metrology Institute. This chapter overviews acoustical measurement instruments such as microphones, acoustic calibrators, and sound level meters. The working principles of these instruments and their calibration procedures, aligned with the applicable IEC standards, will be briefly explained.

Low-frequency noise control is always a challenging issue for an NVH (Noise, Vibration and Harshness) engineer. Acoustic metamaterials are a newly invented class of materials that exploit interesting wave phenomena to control and manipulate sound waves beyond the capability of naturally occurring materials. They are finding increasing use in the field of low-frequency noise control, acoustic super lensing, wave guiding, frequency filtering, and acoustic subwavelength imaging. Space coiling metamaterials and sonic crystals are among the most widely used metamaterials for noise control. They display interesting wave manipulations that lead to extraordinary phenomena such as extreme positive, negative, or zero values of refractive index, wave speed and bulk elastic properties, Fabry-Perot type resonances, spectral band gap formation, local resonances, and Bragg’s scattering. Advancements are ongoing to improve their performance and reduce their limitations. This chapter describes these acoustic metamaterials, particularly, in the context of noise control.

Traffic noise exposure in Indian cities is a major environmental stressor, leading to psychological and physiological health impacts, including annoyance, stress, cardiovascular issues, sleep deprivation, and cognitive impairment. These impacts are primarily assessed using subjective health surveys, which can lead to high ambiguity. This chapter presents an alternative approach to assessing the effect of traffic noise exposure by analyzing psychophysiological signals collected during a listening experiment. This chapter is explained in the form of an experiment which was conducted with 30 participants (15 males and 15 females) exposed to 30 traffic noise stimuli, clustered into silent, active, and loud scenarios. Psychophysiological signals such as EEG, ECG, and SCR were collected in response to noise exposure. The Spearman correlation analysis showed a significant reduction in Alpha band amplitude, especially in the frontal regions, with an increase in loudness level (r = −0.43, p < 0.05), suggesting increased stress and potential implications for cognitive functioning and emotional well-being. The HRV analysis revealed a significant increase in heart rate with an increase in loudness (r = 0.37, p < 0.05). A significant relationship was also observed between skin conductance response and loudness (r = 0.42, p < 0.05), indicating an increase in stress. These changes in psychophysiological signals were also assessed alongside changes in perceived affective qualities (PAQs) and the developed noise clusters. These findings emphasize the complex interplay between noise perceptions and the autonomic nervous system’s response to auditory stimuli, strengthening our understanding of how noise pollution affects health.

In this chapter, an intrinsic damping coefficient is being calibrated by mapping the experimental data with the simulation results, and it is further utilized for dynamic analysis of composite shafts. The experimental impact hammer response of shafts with different compositions of 6061 Al/ Al2O3 is being extracted through a digital vibration analyzer OROS36®. Computational results are obtained by a multiscale modeling approach where effective material properties are predicted through the mean-field homogenization. These properties are utilized as parameters for computing the vibration response of these shafts through a multi-energy domain bond graph approach. Microscopic parameters such as the size of particles, average aspect ratio and compositions are determined by image processing of SEM images of different composite shafts. The experimental investigation clearly depicts the effect of increasing reinforcement in the composite. The amplitudes of vibration are reduced, and the natural frequency of the shafts is increased as the volume percentage of the reinforcement increases. The calibrated parameters provided congruent results with the experimental data.

A study on the acoustic behavior of boards produced from lignocellulosic materials is very important from the point of view of their usage in modern buildings and constructions. Lignocellulosic materials such as wood, natural fibers, etc. are available abundantly and are being processed to produce panels for various applications. In applications such as lecture halls, cinema halls, auditoriums, class rooms, opera halls, etc., the information regarding acoustic properties such as sound absorption coefficient (SAC), noise reduction coefficient (NRC), and sound transmission loss (STL) are essential to evaluate the acoustic performance of the panel products and to enable the required design calculations. The acoustical performance of wood and panel products made from lignocellulosics was described for their use as sound-absorbing material. Using the standing wave method, the acoustic properties, viz. SAC of panel products, are determined, which can be used by the engineers and architects as an input in deriving acoustic efficiency of the room/buildings where these materials are used and also for designing enclosures/buildings for acoustic applications. The chapter includes the SAC and NRC values of the panels of different thickness and density at frequencies ranging from 125 Hz to 4000 Hz assessed in a third-octave band. It is detected that boards with low-density possess high SAC and NRC values when compared to high-density boards. SAC values were also found to increase with a decrease in the board density and vice versa.

In the field of natural language processing (NLP), noise estimation and removal play a critical role in refining and purifying textual data. Noise, which has the potential to obscure the true meaning of text, poses challenges for NLP algorithms. The procedure of NLP pipeline begins by identifying various types of noise in NLP applications. Tokenization, a fundamental step in preprocessing, involves breaking down text into tokens. Additionally, text preprocessing encompasses techniques such as part-of-speech tagging, parsing, stemming, stop word removal, and lemmatization. Modern NLP models necessitate text data to be presented in a vector format, a transformation achieved through feature extraction. Artificial intelligence (AI) driven NLP models harness the power of AI to autonomously remove noise within text, making them indispensable for enhancing quality of text in NLP applications.

A comprehensive overview of seismic signals, waves, instrumentation, and their diverse applications is discussed in this chapter. Natural seismic signals including tectonic earthquakes, volcanic eruptions, landslides, and glacial seismic activity are discussed alongside artificial seismic signals such as collapse earthquakes, excavation-induced signals, and those generated by scientific experiments. The characteristics of seismic waves are examined, focusing on body waves (P and S waves) and surface waves (Love and Rayleigh waves), elucidating their nature and properties emanating from earthquakes. Seismic instrumentation is thoroughly explored, encompassing various sensors like seismometers, accelerometers, geophones, etc. The working principles of different seismometers including broadband, long-period, short-period, borehole, surface, and ocean-bottom variants are detailed, alongside discussions on geophones and the frequency responses of different sensors. A comparative analysis of seismic sensor manufacturers is presented in a tabular format. The components of seismic recorders, including signal sensing, data acquisition, time stamping, power supply, seismic trigger techniques, viz. amplitude and frequency-based triggers, STA over LTA, etc., and communication interfacing, are delineated, with a detailed examination of data formats associated with seismic signals. The chapter delves into the myriad applications of seismic signals and instrumentation, ranging from structural health monitoring to earthquake early warning systems, border intrusion detection, and animal movement tracking for human-animal conflict avoidance. Various seismic research software tools are discussed, underscoring their significance in seismic analysis and research. A brief overview of moonquakes, the cause and types of moonquakes, and the discoveries made by space agencies around the world are presented, adding an extra-terrestrial dimension to the seismic discourse. This comprehensive examination serves as a valuable resource for researchers, engineers, and practitioners involved in seismic studies and applications across diverse fields.

Environmentalists have been more worried about the effects of increasing traffic in recent decades, particularly about the release of greenhouse gases and the widespread problem of noise pollution caused by vehicles on the road. The state of our health and happiness has been profoundly affected by these difficulties. Implementation is still unclear despite massive international studies on noise mapping and possible solutions. Reducing background noise is a critical step in creating long-lasting communities. However, it will be an in-depth understanding of noise’s spatial and temporal dynamics. A noise prediction model to evaluate the Leq on a monthly and daily basis is hence the goal of this work. Using actual traffic data that includes a variety of traffic characteristics, we explore the use of deep learning for traffic noise modeling. To train the LSTM model, 2020 Delhi area noise data from the Central Pollution Control Board was randomly split into 80% training, 10% validation, and 10% testing sets. The LSTM model outperformed the suggested regression model and the existing classical approaches in a head-to-head comparison. The research confirmed that noise pollution is quite common in the region under consideration, urging for immediate action. In line with the expanding data resources of smart cities, the trained model offers real-time forecasts of traffic noise by utilizing data from traffic monitors. This reflects well for future smart city projects. Early decision-making by policymakers is made possible by proactive noise exposure forecasts, which open the door to solutions for reducing noise levels.

The chapter discusses the various factors influencing the sound absorption characteristics of the acoustical materials. The methodology of testing the sound absorption characteristics in the reverberation chamber as per the ISO 354 method is described. The study also discusses the effect of perforation, air gap, density, and thickness of the absorptive material on the sound absorption characteristics of acoustical materials. The chapter also tabulates the large database of sound absorption characteristics of acoustical materials tested in the reverberation chamber as per ISO 354 method to provide insight and understanding to the researchers and engineers about the Sound Absorption Characteristics (SAC) of various acoustical materials. The study shall provide valuable data for architects, engineers, and designers to select appropriate materials for noise control and shall be helpful in the design and development of acoustical materials of enhanced sound absorption characteristics for noise control applications and acoustic comfort in various environments such as offices, auditoriums, classrooms, theaters, convention halls, and industrial spaces.

Building acoustics plays a crucial role in determining the acoustic comfort and functionality of indoor spaces. This chapter provides an introductory overview of key principles and considerations in building acoustics, focusing on both airborne and impact sound transmission. Effective noise mitigation techniques are discussed, encompassing architectural design strategies, material selection, and structural solutions aimed at reducing sound transmission between spaces. The importance of adhering to regulatory standards and guidelines for noise control in various building types is emphasized. By understanding these fundamentals, architects and engineers can design and construct buildings that prioritize acoustic comfort, enhancing overall occupant satisfaction and well-being.

This chapter explores the unique characteristics of acoustic metamaterials, emphasizing their potential for noise control applications. Acoustic metamaterials are at the cutting edge of material science and engineering, utilizing structural design to manipulate sound waves, transcending the capabilities of traditional materials. Their innovative nature lies in offering unprecedented control over sound waves, which facilitates groundbreaking applications and continuous progress in both theoretical and practical domains. The chapter provides an overview of the different types of acoustic metamaterials and their applications. As research increasingly focuses on the sound insulation and absorption properties of these materials, they are becoming crucial for developing novel noise control solutions that surpass conventional technologies.

This study examines the airborne sound insulation properties of various lightweight acoustical materials and masonry constructions, tested in reverberation chambers for use in ceilings, doors, partition walls, noise barriers, and enclosures for traffic, domestic, and machinery noise control. It offers an extensive database of sound transmission loss characteristics measured across the frequency range of 100 Hz to 5 kHz, a resource that is seldom available in existing literature. Additionally, the study outlines the measurement methodology for sound transmission loss, which is widely used in building acoustics. By providing a comprehensive database, this study supports the application of different acoustical materials for noise mitigation and control. It also aids in the design and development of sandwich constructions that offer enhanced sound insulation across the entire frequency range.

Ultrasound has been extensively used in healthcare settings for imaging various internal organs for disease diagnosis and treatment of soft tissue injuries over the past many years. Ultrasound’s usefulness in diagnosing and treating musculoskeletal disorders such as arthritis, tendinitis, shoulder and neck pain, etc., is the primary focus of the present investigation. The investigation elucidates the key differences between diagnostic and therapeutic ultrasound equipment and then summarizes and provides conclusions from the investigations done by previous researchers in the field.

This chapter presents a broad outline of the fundamentals of acoustics, covering the basic principles and concepts that form the foundation of the field. The chapter begins with an introduction to the nature of sound and its propagation, including the fundamental properties of waves and the mechanisms by which sound is generated and transmitted. The chapter then delves into the principles of acoustical measurement, including the various parameters and metrics used to quantify sound and the instruments and techniques used for measurement. The chapter also discusses the behavior of sound in different environments, including the principles of reflection, absorption, and diffraction, as well as the factors affecting the transmission of sound through different media and weak interaction between suspended particles and dispersion medium. Finally, the chapter explores the applications of acoustics in various fields, including music, architecture, and engineering, highlighting the importance of understanding the fundamentals of acoustics in these and other areas. Overall, this chapter serves as a comprehensive introduction to the fundamental principles of acoustics, providing a solid foundation for further study and exploration in the field.

Sound communication plays a crucial role in the animal kingdom, enabling various species to transmit information, establish social bonds, and coordinate complex behaviors. The present chapter overviews sound communication’s diverse mechanisms and functions across different taxonomic categories, highlighting its significance in shaping ecological interactions and evolutionary processes. The physical and physiological aspects of sound production and reception in nature’s species, including the resonating calls of birds to the low-frequency vibrations of elephants, specialized anatomical structures and behaviors to generate and perceive sound waves, effective long-distance communication, overcoming environmental challenges, and enhancing survival strategies. Furthermore, the chapter delves into the multifaceted functions of sound communication in the animal kingdom. In many species, vocalizations serve as a means of intraspecific communication, allowing individuals to attract mates, establish territories, assert dominance within social hierarchies, and establish an important alarm system for rapid response to potential threats. Vocalizations among social mammals alert conspecifics and facilitate collective defense mechanisms as a communication means for parental care and kin recognition, enabling individuals to locate offspring, coordinate feeding efforts, and reinforce familial bonds.Finally, it touches upon the evolutionary implications of sound communication. The diversity of vocalizations, complexity, and cultural transmission within certain species highlight the potential for sound-based communication to shape social structures and promote genetic diversity. Furthermore, selective pressures and ecological factors have influenced the evolution of specialized sound-producing and sound-receiving organs, underscoring the importance of sound as an adaptive trait. Therefore, sound communication is fundamental to animal behavior, facilitating interactions within and between species. Through an exploration of the mechanisms, functions, and evolutionary implications of sound communication, it underscores the significance of acoustic signals in shaping the ecology and behavior of nature’s diverse species. The way forward for futuristic studies in sound communication is also briefly outlined.

Acoustic studies in biological media have emerged as a dynamic and interdisciplinary field of research, offering profound insights into the intricate relationships between sound and living organisms. This chapter provides a concise overview of the multifaceted investigations within this burgeoning domain, shedding light on the fundamental principles, cutting-edge methodologies, and promising applications that define its significance. It covers the interaction of acoustic waves with biological tissues, imaging modalities, and emerging advancements in the field. In the realm of biological media, the use of acoustic waves as a probing tool has uncovered a multitude of revelations. These studies delve into the diverse mechanisms by which organisms generate, perceive, and interact with sound. Moreover, the field of acoustic studies in biological media leverages advanced techniques such as ultrasound imaging, sonar systems, and underwater acoustics to explore the anatomical and physiological aspects of living organisms. This has profound implications for medical diagnostics, non-invasive monitoring of health, and the preservation of endangered species, among other applications.Biological media, whether in the form of biological tissues, aquatic environments, or terrestrial ecosystems, present unique challenges and opportunities for acoustic exploration. Researchers employ a variety of tools, ranging from state-of-the-art hydrophones and transducers to computational models and artificial intelligence algorithms, to unravel the secrets concealed within these complex acoustic landscapes. In a nut shell, acoustic studies in biological media offer a captivating journey into the sonic world of nature, where scientists unravel the mysteries of communication, navigation, and adaptation in living organisms. The ever-evolving methodologies and applications in this field hold great promise for enhancing our understanding of the natural world, improving healthcare, and advancing environmental conservation efforts. As the frontier of acoustic research in biology continues to expand, its potential to transform our knowledge of life on Earth remains boundless.

The world of acoustics has seen remarkable advancements in recent years, thanks in large part to disruptive metrology techniques. These innovations have not only improved our understanding of sound but have also paved the way for groundbreaking developments in various fields, from healthcare to entertainment. Through an in-depth analysis of disruptive metrology methods, we aim to shed light on the exciting possibilities that lie ahead for acoustical innovations. The field of acoustics has witnessed remarkable progress in recent years, thanks to disruptive metrology techniques that have revolutionized the way we measure and understand sound. This chapter provides an overview exploring the significance, applications, and potential societal impact of these innovative measurement methods. Furthermore, the chapter discusses several disruptive metrology techniques, including near-field acoustic holography, acoustic metamaterials, acoustic tomography, and computational acoustics, emphasizing their contributions to the evolution of acoustical innovations. By pushing the boundaries of traditional measurement practices, disruptive metrology opens new avenues for research and development, promising a future where sound can be harnessed in ways previously unimaginable.

This comprehensive chapter discusses the historic evolution, forms, and advancements of sound navigation and ranging (SONAR) sensors. Straddling from its start during World War I to its current advanced capabilities, the chapter highlights how SONAR technology has transmuted from basic acoustic hearing devices to erudite systems critical for underwater navigation, research, defense, and environmental conservation. It examines various types of modern SONAR sensors, including single-beam, multibeam, side-scan, forward-looking, Doppler, and synthetic aperture SONAR, clarifying their varied applications in underwater exploration, mapping, object detection, and current measurement. Furthermore, the chapter discusses the continuous innovations driving SONAR technology forward, emphasizing the integration of artificial intelligence, advancements in signal processing, and the potential for underwater communication networks. It underlines the concerted exertions among academia, industry, and government entities as key issues in pushing research and development in this field. The chapter also highlights the role of SONAR technology in untying the secrecies of the oceans, supporting scientific findings, endorsing safe navigation, contributing to environmental conservation, and nurturing advancements across various industries reliant on underwater exploration.

Ultrasonics, a branch of acoustics dealing with sound waves beyond the frequency range of human hearing, plays a crucial role in the non-destructive evaluation and characterization of materials at elevated temperatures. In materials science and engineering, ultrasonic techniques provide valuable insights into the internal structure, mechanical properties, structural transformations/phase transitions, and overall integrity of materials. High-temperature material’s characterization using in-situ ultrasonic parameter measurement is a valuable technique in materials science and engineering, and metallurgy. The temperature-dependent ultrasonic velocity and attenuation are the key parameters for the high-temperature material’s characterization. This approach involves monitoring the changes in ultrasonic velocity and attenuation of materials at elevated temperatures, providing insights into their mechanical and structural properties under desired conditions. The velocity of ultrasound measured as the function of temperature can be influenced by temperature-induced changes in the material’s properties. The changes in attenuation can reveal information about material microstructure and defects. In the pursuit of developing materials for high-temperature applications, understanding their behavior under systematic thermal conditions is paramount. The in-situ ultrasonic velocity and attenuation measurement emerge as a powerful tool, offering real-time insights into the structural and mechanical transformations materials undergo at elevated temperatures. This chapter covers the significance, advantages, experimental set-up, and key components of employing in-situ ultrasonic techniques for characterizing materials in high-temperature environments. This chapter also outlines the characterization of temperature-dependent phase/structural changes existing in the functional materials such as perovskite, ferrites, and bio-glasses.

Noise pollution is a significant environmental issue, leading to various auditory and nonauditory health problems. Traffic noise, particularly in urban areas of developing nations like India, is a major contributor to this pollution. The heterogeneous transportation system and prevalent honking have significantly altered the noise climate in these countries. This chapter explores the conventional and psychoacoustical approach to assess the traffic noise scenario in these countries. It examines conventional methods of traffic noise assessment, including traffic noise modeling, noise mapping, and noise annoyance modeling. Additionally, the chapter introduces the “soundscape” approach, which is based on the psychoacoustic approach focused on perception of sound by receivers. It is observed that noise levels in India are considerably higher on the Indian urban street typically ranging between 73 and 86 dB. There is a need to reconsider European noise mitigation standards when applying it to the Indian context. The noise annoyance model is an effective way to understand the impact of traffic noise exposure, which also needs to consider the noise sensitivity and other sociodemographic details of the listeners. Furthermore, the psychoacoustic and soundscape approaches are identified as more human-centric methods for assessing the impact of these noise levels on the community.

Sound Absorption Coefficient (SAC) evaluation at various frequencies in 1/3rd octave band is very important for passive noise control. Reverberation Chamber and Sound Impedance Tube facility is widely used for measurement of SAC of acoustical materials. However, both these methods are time-consuming and need rigorous experimentation in order to evaluate and analyze the SAC of acoustical materials. The analytical models thus prove to be very helpful in simulation and devising newer acoustical materials of enhanced SAC. The analytical models also sometimes suffer from disadvantages of high prediction errors. The present chapter thus explores the use of Artificial Neural Network (ANN) in order to predict the SAC of acoustical materials based on the input values of some nonacoustical parameters. The prediction model so developed and tested for its performance using some statistical tests. The study concludes that ANN can be used as a reliable tool for SAC prediction of acoustical materials.

The use of ultrasonics in materials synthesis offers a versatile and powerful approach to synthesis nanomaterials with unique properties. Sonochemical synthesis is a method that employs high-frequency ultrasound waves to drive chemical reactions, resulting in the creation of nanomaterials. This approach binds the physical and chemical impacts of ultrasound-induced cavitation, which involves the formation, expansion, and explosive collapse of bubbles in a liquid medium. The asymptomatic conditions generated by ultrasonic cavitation in appropriate chemical precursors open new pathways for material development, with significant implications across various fields, from catalysis and energy to medicine and environmental science. The sonochemistry controls the physical effects of ultrasonic cavitation—specifically, the formation, growth, and implosive collapse of bubbles in a liquid medium—to create localized extreme conditions that facilitate unique chemical reactions. These conditions, characterized by high temperatures and pressures, promote the efficient formation of nanomaterials with controlled size, shape, and composition. The book chapter on ultrasound-based sonochemical synthesis of nanomaterials is crucial for advancing the field of nanotechnology. It not only provides a comprehensive review of the principles, techniques, and applications of sonochemical synthesis but also addresses the current challenges and future directions.This chapter begins with an overview of the basic principles of ultrasound and cavitation, followed by a detailed discussion on the selection of precursor materials and solvents, and the various parameters influencing the synthesis process. The key advantages of sonochemical methods, such as mild reaction conditions, scalability, versatility, and enhanced reactivity, are highlighted. Further, the chapter covers a wide range of applications for sonochemically synthesized nanomaterials, including catalysis, biomedical uses, energy storage, and environmental remediation. Finally, the chapter addresses the current challenges in the field, such as achieving uniform size and shape distribution, optimizing large-scale production, and managing energy consumption. Future directions and potential advancements in ultrasound-based sonochemical synthesis are also discussed, emphasizing the ongoing research efforts to overcome these challenges and fully harness the potential of this innovative technique.

This chapter investigates the advanced application of non-destructive technique like ultrasonic techniques for detecting defects in lithium-ion batteries, with a focus on state of health (SOH) estimation, state of charge (SOC) estimation, and battery temperature detection. Through a comprehensive analysis, we demonstrate that ultrasonic methods offer noninvasive, precise, and reliable monitoring solutions that are essential for ensuring the integrity and performance of lithium-ion batteries. Ultrasonic SOH estimation enables early detection of internal structural changes and degradation, ensuring timely preventive maintenance and enhancing battery safety and long-lasting nature. For SOC estimation, ultrasonic techniques provide accurate real-time measurements by analyzing changes in acoustic properties, improving charge management, and extending battery life. Additionally, ultrasonic temperature detection offers detailed assessments of internal temperature variations, preventing overheating and optimizing thermal management systems. The integration of these ultrasonic methods significantly advances battery management systems, supporting the increasing demand for dependable energy storage solutions that spans over different applications viz electric vehicles, portable electronics, and large-scale energy storage systems.

This chapter explores the different factors influencing the impact of noise on human health. Noise pollution has the potential to diminish the overall quality of life within a community. Reducing background noise, particularly in urban environments, can significantly enhance individual physical and mental health as well as their social welfare. The chapter discusses a concise overview of noise regulations and laws, both domestic and worldwide. Excessive noise exposure can lead to detrimental health impacts such as heightened stress levels, disrupted sleep patterns, and diminished hearing abilities. Prolonged exposure to loud noise can lead to many health issues, as is evident in recent studies, such as hypertension, etc. Ensuring good health necessitates the effective control of noise levels in both residential and professional settings. The study also presents various national and international standards, regulations, guidelines, and best practices pertaining to noise pollution, assessment, and control.

Data quality, especially in underwater scenarios, is the ultimate factor in deciding the success or failure of the measurement system. Transducers are performing out of their intended specification requirements, leading to false data being measured. Data quality must be established categorically before it is used for any analysis application. The calibration is fundamental for accurate measurements and to estimate the characteristics of hydrophones. Calibration establishes the relationship between the measured values and those realized by the reference standard under specified conditions. This chapter outlines the methods used for underwater electroacoustic transducer/hydrophone calibration. It is also describing about the underwater acoustic terminologies and preconditioning of transducers before being calibrated. The sources of uncertainties pertaining to each method are also explained in this chapter. Absolute uncertainty can never be achieved, and hence the uncertainty range is estimated with a traceability chain with a reference to national or international standards. The procedure described here is on the basis of the IEC 60565 standard and the basis of any quality assurance program and complements the essential requirements for accreditation.