ONLINE QIP Short Term Course on Muffler Acoustics for Automotive Engine Noise Control

14-19 March 2021

Course Objective

To familiarize teachers and practicing mechanical engineers to different aspects of engineering noise control as well as fundamentals of acoustics.


Dr. Akhilesh Mimani
Department of Mechanical Engineering
Indian Institute of Technology Kanpur

Overview of the Course

Engine exhaust noise being one of the major contributors towards environmental noise pollution, the design and analysis of exhaust mufflers has been a crucial area of research in the field of engineering noise control. Additionally, there exists a significant literature towards designing silencers for reducing fan noise in ventilation and air-conditioning systems. This QIP course presents a set of dedicated lectures on the theory of exhaust mufflers used for reciprocating internal combustion engines as well as ventilation ducts, and so on. While a basic background in Acoustics is desirable, the course begins with fundamentals including concepts on noise control engineering, detailed derivation of the 1-D wave equation and planar wave solutions, boundary conditions and impedance concept. This is followed by an introduction to the terminologies common in mufflers as well as the basic elements constituting acoustic filters including elctro-acoustic circuit analogies and 1-D or plane-wave analysis. Next, considering planar wave propagation, the flow-acoustic analysis of perforated duct mufflers, and network analysis of multiply-connected complex muffler systems is explained. Advanced three-dimensional analytical methods for evaluating the acoustic attenuation performance of reactive mufflers are presented. Following this, the theory of Dissipative and Parallel Baffle Mufflers are taken up. The course ends with presentation of, and emphasizing important design concepts and topics to be covered for future courses.

Course Content



Noise-Control Strategies (Sound source modification, control of transmission path, modification of receiver path, Airborne and structure-borne noise)

Acoustic Field Variables: pressure and velocity fields, sound speed, acoustic potential

Wave equation and its solution: Plane and spherical waves, Progressive and Standing waves

Concepts of time and frequency-domain representations

Open and closed-end boundary conditions, resonances in 1-D ducts,

Acoustic Impedance, Near- and Far-field, Intensity and Sound Power

Units: Sound Pressure, Intensity and Power levels

Combining Sound Pressures: Adding of coherent and incoherent sound pressures, Beating phenomenon, Subtracting sound pressure levels


Analytical solution of plane wave propagation in 1-D ducts

Radiation impedance at a pipe end with and without flange

Lumped System Analysis: Inertance and Compliance

Lumped Analysis of a uniform pipe closed/open at an end, concept of end-correction

Helmholtz Resonator, Quarter-wave resonators, Extended-tube resonators, Concentric Hole-Cavity Resonators,

Electro-Acoustic Analogy and Layout of a typical engine exhaust system, Thevenin and Norton forms

Classification of muffling devices: Reactive dissipative, and hybrid mufflers,

Muffler Performance Measures: Insertion Loss, Transmission Loss & Level Difference


Simple Area Discontinuity & Transfer Matrices (Four-pole parameters)

Impedance matrix characterization

Expression for Transmission Loss performance

Simple Expansion chamber analysis using Transfer Matrix method

Extended-Inlet and Extended-Outlet Muffler Analysis

Side-Inlet and Side-Outlet Muffler using Transfer Matrix method

Extended-Inlet and Side-Outlet Analysis using Transfer Matrix method

Wave propagation in gradually varying area ducts: Webster’s horn equation

Exponential and Conical ducts, Segmentation and Matrizant approaches


Aeroacoustic state variables Transfer Matrix for a Tubular Element (Uniform pipe)

Transfer matrix for Extended-Inlet and Outlet element & Use of perforated elements in commerical mufflers

Two-interacting duct configurations: Concentric Tube Resonators (Fully and partially perforated)

Review of Perforate impedance expressions

Cross-Flow elements of expansion- and contraction-type, Plug-mufflers and Three-pass perforated tube mufflers

Multiply-connected mufflers: Herschel-Quincke (HQ) Tubes

Network analysis and Integrated transfer matrix method for complex muffler configurations, Conical Concentric Tube Resonators (CCTRs)


3-D Acoustic Wave Equation in Rectangular and Circular Waveguides: Derivation, Modal Solution and Concept of Cut-on Frequency

Three-dimensional muffler analysis: Necessity, Overview of different analytical methods

Green's function or Point-Source Model, Piston-driven model - Expansion and Flow-Reversal chambers, Side-inlet and side-outlet systems

Analytical mode-matching method for extended-inlet and extended-outlet muffler element


Dissipative mufflers: Local and bulk reaction type, lined duct silencers, flow effects, hybrid or combination type silencers, parallel baffle silencers, Pod silencers

Pressure-Drop considerations

Requirements & Practical considerations of an Engine Exhaust Muffler including guidelines on design of muffler shell and end-plates

Topics for future courses: Experimental method in muffler acoustics and engine source characteristics, Numerical techniques such as Finite-Element Analysis, Break-out noise considerations

Assignment problems

Learning Outcomes

The participant should be able to technically converse with practicing noise consultants and acoustic engineers across the country.

Will be able to teach a basic course in their parent organization

Will be able to understand and relate the acoustic and noise control concepts in daily applications, especially in relation to silencer design

It is anticipated a few interested participants can take up a career in Noise control engineering – possibly by pursuing a higher degree in these fields.

Registration Procedure

Attendance is mandatory to receive Course Certificate.

1. Faculty from AICTE Institutes coming under QIP program
(maximum 30)
No Registration fees
2. Faculty from private/autonomous Institutions:
Non IITK Faculty
Rs. 7,080/- (Including GST)
3. Students of IITK
IITK Student
Rs. 2,000/-
4. Students from other Educational Institutions:
Non IITK Students
Rs. 4,130/- (Including GST)
5. Participant from Industry and R&D labs:
Industrial Participant
Rs. 14,160/- (Including GST)
Only faculties from AICTE approved institues will be allowed
Only 30 faculy members are allowed under QIP category
No Registration fee is required

Step 1: Make Payment according to your category

Instructions, How to Pay? Click Here

Online Payment Link: Click Here

Details to be filled during payment:

Course Code 2020/22
Course Title Engineering and Environmental Noise Control
Course Duration 14/03/2021 to 19/03/3021
Participants Category
Course Fees + 18% GST
IITK Students needs to pay only course FEE
IITK Student (Rs. 2,000/-)
Non IITK Student (Rs. 4,130/-)
Non IITK Faculty (Rs. 7,080/-)
Industrial Participants (Rs. 14,160/-)

Step 2: Fill out the registration form:

Registrations have been closed

In case of any query You can contact to QIP Office: 0512-259-7795

Contact Person

Contact to following person in case of any query related to registration...

Vinay Kumar
QIP IIT Kanpur
Phone: 0512-259-7795

Yogendra Singh
QIP IIT Kanpur
Phone: 0512-259-7795