Principal Concepts in Acoustics and Noise Engineering is a comprehensive textbook offering both fundamental and advanced insights into acoustics and noise control. It presents a balanced approach between theoretical foundations and real-world applications. The content is organized to systematically address sound propagation, measurement, and control.
The book begins with basic acoustic principles and terminology, gradually progressing to advanced topics such as the acoustic wave equation, spherical wave behaviour, sound radiation, and transmission through different media. It also explores the human auditory system, covering hearing mechanisms, loudness perception, and hearing impairment.
Detailed coverage is provided on noise measurement methods, evaluation standards, and regulatory guidelines relevant to industrial, environmental, and occupational noise. The text discusses various noise control techniques implemented at the source, along the transmission path, and at the receiver, with emphasis on solutions for machinery noise including acoustic enclosures, passive mufflers, and active noise control systems.
The final section addresses room acoustics, focusing on sound reflection, absorption, reverberation, and acoustic design principles for spaces such as classrooms, studios, and auditoriums, offering guidance on enhancing acoustic quality in built environments.
Each chapter presents key concepts clearly, supported by illustrations and solved examples that link theory to practical problems. To support learning and review, every chapter includes practice questions, suggested readings, and case-based insights where applicable, Principal Concepts in Acoustics and Noise Engineering serves as a thorough resource for developing a deep understanding of acoustics and noise engineering.
This book is particularly useful for UG and PG students in mechanical, civil, and environmental engineering. It also serves as a valuable reference for engineers, consultants, and researchers working in acoustic design, noise mitigation, and related areas.
Here is an excerpt from the book:
3.4 INTRODUCTION TO POLAR COORDINATES AND POLAR GRID
Two-dimensional polar coordinates
In the Cartesian coordinate system, points are plotted using horizontal and vertical movements. However, there is an alternative system for graphing points in a plane known as the polar system. In this system, points are determined by their distance from the origin and their angle from the positive x-axis.
The two-dimensional polar coordinate system defines each point on a plane in terms of its distance from a reference point (r) and its angle from a reference direction (θ) (Fig. 3.3). In the polar coordinate system, the origin is called a pole which is the reference point. The polar axis refers to the line that serves as the reference direction in the polar coordinate system, extending from the pole in the specified direction.
We can express the point on a plane as a polar coordinate (r, θ) rather than using the cartesian coordinates (x, y) (Fig. 3.3).
In Fig. 3.3, x = r cos θ and y = r sin θ and
x2 + y2 = r2(cos2 θ + sin2 θ)
x2 + y2 = r2 → r = √x2 + y2
y/x = (r sin θ)/(r cos θ) → tan θ = y/x → θ = tan-1(y/x)
Polar grid
A polar grid is a coordinate system used to represent points in a plane using polar coordinates. Instead of using Cartesian coordinates (x, y), which measure distance along horizontal and vertical axes, polar coordinates represent a point by its distance from the origin (r) and the angle (θ) it forms with the reference direction (usually the positive x-axis). A polar grid consists of concentric circles (representing different values of r) and radial lines (representing different values of θ), providing a way to visualize and locate points in the plane using these coordinates.
Example for graphing the polar coordinates (3, 45°) in a polar grid
To plot the point (3, 45°), start by facing down the positive x-axis from the origin, as if you are standing at the origin looking east. Then, rotate 45° counterclockwise and move 3 units away from the origin (Fig. 3.4).
Three-dimensional polar coordinates
The spherical coordinates are defined by three parametres: the distance from the origin and two angles. The position of a given point in space is specified by three numbers, (r, θ, φ). Here, r is the distance of from the origin; θ is called polar angle which is measured between the z-axis and the radial line r; φ is called the azimuthal angle which is measured between the orthogonal projection of the radial line r onto the reference x-y-plane and the fixed x-axis (Fig. 3.5).
The spherical coordinates (r, θ, φ) are related to the Cartesian coordinates (x, y, z) by
r = √(x² + y² + z²)
φ = tan-1(y/x)
θ = cos-1(z/r)
In terms of Cartesian coordinates:
x = r cos φ sin θ
y = r sin φ sin θ
z = r cos θ
To read more about Principal Concepts in Acoustics and Noise Engineering, click here for complete details, chapter breakdowns, and author information.
This will guide you through its key features, content highlights, and how the book supports study and practice in acoustics and noise control.
