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Last Modified : Tue, 22 Jan 19


  • Instructor: Jont Allen (jontalle@illinois.edu)
  • Class Time: 12:30-15:50 Tues/Thur, Place: 3081-ECEB; ECE, UIUC, UI Calendar
  • Lectures will be presented on Tuesdays and Labs on must Thursdays (see schedule for details). Lab teams will compete in small groups of 3-4 students.
  • Office hours: Mondays, Friday 2:30-4:00pm; ECEB-4034
  • Text: Beranek & Mellow (2012) UIUC-ebook; Buy; Browse; Reference text: Electroacoustics (pdf) **Topics: Transducer design & analysis: 2-port networks, loudspeakers, microphones; acoustic wave phenomena; acoustics of rooms and auditoriums; artificial reverberation and sound localization; Topics in digital audio.
  • Homeworks: There will be 5 homework assignments (HW A-E); Links to these assignments are available in the Daily Schedule below.
    Many of the problems are directly taken from the homework problems in anInvitation pdf.
  • Labs Labs always on Thur (but not every week: see schedule).
    Session 1: Thursdays 11:30AM-2:30PM
    Session 2: Thursdays 1:30AM-3:30PM. groups
    • Lab manual In preparation for each lab, please prepare by reading the corresponding TO DO section of the manual.
    • Lab location: 4022 ECE (you have ICard access). Four network-analyzers (MU boxes) in cabinet on right
      **Software for Labs: G7-software (runs on Octave and/or Matlab;Supports MS-Windows, MAC and Linux. See Lab Manual for details).
    • Tools: MATLAB, Octave, Latex GUI (Not sure you need to register)
  • Exam 1, Exam2, Final Report: Format for final report pdf, LaTeX example: zip
  • This week's schedule

Spring 2019 Daily Schedule

Part I: Basic Acoustics (Chaps. 1-2: 3 Lect)
M 1/14 First day of instruction, Spring 2019
1 3 T 1/15 *Lect: Introduction: We will study how loudspeakers work, both basic theory & hands-on lab experiments.
*Anatomy of a loudspeaker
*Review of Basic Acoustics (Pressure and Volume velocity, dB-SPL, etc.)
*Acoustic Intensity & Energy density, Level in Decibels [dB]
*Read Text: BeranekMellow, Ch 1, p. 1-17; History (pdf)
2 R 1/17 *Lect: Derivation of the wave equation & Webster Horn equation
*Impedance {$Z(s)$} and complex functions of complex frequency {$s$}; Example of a 1{$^{st}$}-order lowpass filter;
*Read Text: Ch 2, p. 21-28 (Wave Equation) and derivation pdf

3 4 T 1/22 *Lect: Solutions of the wave equation
*Impedance (i.e., Brune) as boundary conditions {$Z(s)=N(s)/D(s)$}: Residue expansions
*Inverse Laplace transform; Convolution of vectors {$\leftrightarrow$} product of polynomials
*Read Ch 2, p. 29-51
*Homework A (Discuss on Lect 5; DUE Lect 7)
Part II: Circuit Analysis (Chaps. 3-4: 4 Lect, 1 Lab)



R 1/24 *Lect: Mechanical impedance {$Z_m(s)=$} Force/Velocity: Mass, stiffness, resistance
*Applications of the Laplace transform {$h(t) \leftrightarrow H(s)$}: Fourier {$\cal F$} and Laplace {$\cal L$} Transforms;
[e.g.: {$\delta(t) \leftrightarrow 1$}, {$\delta(t-T) \leftrightarrow e^{-j\omega T}$}; {$1\leftrightarrow 2\pi\delta(\omega)$}, etc.]
*Notes on the Laplace {$\delta(t)$} function (i.e., is {$u(t) \equiv \int_{-\infty}^t\delta(t)dt$} a function?)
*Brune impedance and its properties: Network Postulates:Causal; stable; stable inverse; Conservation of Energy ({$\Re Z \ge 0$})
*What is a Network analyizer? (MU box Demo)
*Lab 0 (3081 ECEB): Define Lab partners
*Read Ch 3, p. 65-84; Integration in the complex {$s$} plane pdf
5 5 T 1/29 *Lect: Acoustic Impedance: {$Z_a(s)=$}Pressure/volume-velocity
*2-port Transmission Matrix {${\bf T}(s)$} (ABCD)
*Comparison of the step function {$u(t)$} for {$\cal F$} & {$\cal L$} transforms
*Inverse Laplace Transform {${\cal L}^{-1}$} definition: Residue Thm
*Discuss HW-A
*Read Ch 3, p. 84-94
6 R 1/31 *Lect: Electrical impedance: {$Z_e(s)=$}Voltage/Current
*Definition of, and conversion between Transmission matrix {${\bf T}(s)$} & Impedance matrix {${\bf Z}(s)$}
*Meaning of {$A(s), B(s), C(s), D(s)$}
*Brune impedance: Minimum phase (MP), positive real (PR)
*Review: Ch 3 Transmission {$\Leftrightarrow$} Matrix: VanValkenburg & Pipes (pdf) &
Network Postulates: Carlin, Kim et al
7 6 T 2/5 *Lect: Lumped approximations of Transmission lines and the {${\bf T}(s)$} (ABCD) method
*Transfer functions: all-pole (IIR), all-zero (FIR) and all-pass (pol-zero) functions
*Complex Functions of a complex variable
*Time vs frequency domain impedance
*Thevenin and Norton equivalence representation
*Homework B (EvalResp.m) (Discuss on Lect 9; DUE Lect 11)
*Read Ch 3, p.106-118

R 2/7 *Lab 1 (4022 ECEB): Setup of hardware; Learn how to make impedance measurements: Lab manual
*Install g7play software package
*Construct circuit board to measure loudspeaker impedance, and debug it by measuring a resistor in series with a capacitor having RC time constant of 2 ms and cutoff freq=1/2{$\pi RC$}.
*Read: Lab manual
Part III: Electrodynamic Loudspeakers (Chap. 6: 4 Lects, 2 Labs, Exam I)
9 7 T 2/12 *Lect: Analysis of the Twin-Tee network: How to put two Transmission networks in parallel
Discussion of the dB & Bode plots (log-log frequency response plots)
Review of lab setup with op-amp circuit & how to verify the setup is functional
*Discuss HW-B/Lab exercise (Due Lect 11)
*Read Ch 3 ABCD Matrix analysis of circuits

R 2/14 *Lab 2 (4022 ECEB):
*Measurement of 2-port RC (example from HWb) (EvalResp.m)
*Read Ch 6 Electrodynamic loudspeakers
11 8 T 2/19 *Lect: Hunt's 2-port impedance model of the loudspeaker
*2-port networks: Transformer, Gyrator and transmission lines
Moving coil vs. Balanced armature Loudspeaker Motional impedance (Hunt Chap. 2, p. 92-97 pdf)
*Faraday's Law of Induction: differential & integral form; Ampere's Law & Ampere's Force Law
*Reciprocity: PZT, Capacitance & Electrodynamic microphones
*Homework C (Discuss on Lect 13; due Lect 14), SpeakerModel.m
*Read Ch 3, p. 94-96 Speaker motor

R 2/21 *Lab 3 (4022 ECEB): Measure Mass-loaded speaker impedance {$Z_e(f)$}
*Speaker Faced-Up vs. Faced-Down; {$Z_{mot}$}
*First measurement of a loudspeaker input impedance
*Read 107-112 Transducer impedance + Lab 3 of Lab manual
13 9 T 2/26 *Lect: Reciprocal and reversible 2-port networks (T and Z forms)
*The Reciprocal calibrationmethod (i.e., cascaded loudspeakers)
*Forward, backward and reflected traveling waves
*Uniform Transmission lines & reflections at junctions
*Discuss Homework C (Due 3/2)
*Read Mason 1928; Text: 4.23, p.180-198
14 R 2/28 *Lect: Thevenin & Norton parameters of a loudspeaker: {$P_0(f), U_0(f), Z_0(s)$}
*Propagation in horns having viscous and thermal loss
*Review for Exam I for Lectures 1-12, HW-A,B,C
*Read p. 106-107

15 10 T 3/5 NO class: Exam I; You may use your final report during the exam; Tuesday March 5, @ 7-9PM Room: 3081 ECEB
Part IV: Horns with Viscous & Thermal loss; Reciprocity (Chaps. 9-4: 6 Lect, 3 Labs)
16 R 3/7 *Lect: Acoustic transmission lines
*Homework D: Acoustics & Transmission Lines (Discuss on Lect 17; due Lect 19)
*Read Sect. 17.19, p. 358-373
3/10-3/11 [Engineering Open House]
17 11 T 3/12 *Lect: Reciprocity calibration of a loudspeaker: How To.
*Discuss HW-D
*Read Lab 3-4, p. 14-19

R 3/14 *Lab 4 (4022 ECEB): Reciprocity calibration; verification with a probe microphone (Etymotic Research-7C)
12 M
3/16 Spring Break
19 13 T 3/26 *Lect: Speaker Acoustic Thevenin calibration using 2 or more acoustics loads
*Read: Thevenin model of source

R 3/28 *Lab 5 (4022 ECEB): Speaker Acoustic Thevenin calibration using 2 acoustics loads (Duct tape)
*Homework E (Discuss on Lect 23; DUE Lect 24); Starter files for middle ear simulation (txline.m, gamma.m)
*Read: ABCD for Thevenin source
21 14 T 4/2 *Lect: Spherical wave around a sphere; Radiation (wave) impedance of a sphere
*Spectral Analysis and random variables: Resistor thermal noise (4kT) Noise Theory, About Nyquist
*Wave equations and Newton's Principia (July, 1687); d'Alembert solutions in 1 and 3 dimensions of the wave equation
*Read Solution to spherical wave equation

22 R 4/4 *Lab 6 (4022 ECEB): Measure the speaker radiation impedance {$Z_{rad}(s)$} and compare to the spherical radiator
*Read: Radiation impedance of sphere


15 T 4/9 *Lect: How does the middle ear work? Ans: The Middle ear is a transmission line.
*Read: Rosowski, Carney, Peak (1988) The radiation impedance of the external ear of cat (pdf)
*Discuss HW-E
24 R 4/11 Lect: Topics in Audio
*Vacuum Tube guitar amplifiers pdf
*Transmission Lines discussion; Monster speaker cable
*Loudspeakers: lumped parameter models, waves on diaphragm
*Throat and Radiation impedance of horn
*Review for Exam II (HW-D,E)

25 16 T 4/16 NO Class: Exam II You may use your final report during the exam Thursday April 11, @ 7-9PM Room: 3081 ECEB
Part V: Topics in Audio Engineering (Chaps. 10-11: 3 Lects., 2 Labs)

26 R 4/18 *Lab 7 (4022 ECEB): Choice of 1) Earbud in ear simulator, 2) Horn baffle, 3) Acoustic suspension baffle (AR-3)
*Work on lab report (Example LaTeX)
17 T 4/23 *Lect: Baffling loudspeaker topics
*Read Ch7, p. 289-320
28 R 4/25 *Guest Lecture: ???Mead Killion??? CEO Etymotic Research, Elk Grove Village IL
29 18 T 4/30 *Last Lect in 4022; Open discussion of Lab report content; Class discussion: What did you learned?
W 5/1 Instruction ends
R 5/2 Reading Day
F 5/3 Group lab reports due by midnight: Please give me both a paper and pdf copy. NO DOC files
*Final Exams begin (Our final is the lab project oral presentation on loudspeakers)
W 5/8 Group presentations 1:30-4:30pm (during officially scheduled Final Exam


  • The primary text is Acoustics: Sound fields and transducers Beranek and Mellow; Academic Press 2012;
  • The reference textbook is Electroacoustics: The Analysis of Transduction, and Its Historical Background by Frederick V. Hunt. ISBN 0-88318-401-X.
    • Chapters 2+ of the reference textbook are available pdf.

Reading Assignments:

  • Part I: Beranek 1-17, 21-29, 37-48
  • Part II: Beranek 65-84, 84-94, 106-118, Kim et al, Carlin, VanValkenburg-Pipes)
  • Part III: Beranek 119-128, 94-96, ??
  • Part IV: ??
  • Part V: 289-320, Ch 11


  • HW-A, Assigned 1/22 (Lect 3), DUE Lect 7 : Acoustics and LT/FT
  • HW-B, Assigned 2/5 (Lect 7), DUE Lect 11: T, Z matrix + Transmission line theory
  • HW-C, Assigned Lect 11, DUE Lect 14: Electrodynamic ABCD model with Gyrator, Motional impedance & {$Z_A(s)$} TL load
  • HW-D, Assigned Lect 16, DUE Lect 19: Horns, reciprocity, Thevenin model of Johnson resistor noise
  • HW-E, Assigned Lect 20, DUE Lect 24: Middle ear model


  • Lab Lab Manual
  • Lab 0, Lect 4, Thurs 1/24, 3081 ECEB : a) Define teams; b) Define goals of Labs
  • Lab 1, Lect 8, Thurs 2/7, 4022 ECEB : a) Op-amp circuit construction; b) MU calibraton with a 1 kohm resistor
  • Lab 2, Lect 10, Thurs 2/14, 4022 ECEB : Measure 2-ports: (video)
    a) RC lowpass (EvalResp.m),
    b) Twin-Tee notch filter
  • Lab 3, Lect 12, Thurs 2/21, 4022 ECEB : Speaker electrical impedance:
    a) Loaded,
    b) Unloaded,
    c) Compute speaker motional impedance

(syms algebra: MassCal.m, calculation: calcHuntParams.m)

  • Lab 4, Lect 18, Thurs 3/14, 4022 ECEB : Reciprocity calibration with probe mic verification

(syms algebra: RecipCal.m)

  • Lab 5, Lect 20, Thurs 3/28, 4022 ECEB : Thevenin Equivalent circuit via 2 acoustic loads (Duct Tape cavities)
  • Lab 6, Lect 22, Thurs 4/4, 4022 ECEB : Measure speaker acoustic radiation impedance {$Z_{rad}$}
  • Lab 7, Lect 26, Thurs 4/18, 4022 ECEB : Optional lab (team's choice):
    a) earbud in ear simulator,
    b) Wave horn baffle,
    c) AR-3 Acoustic Supension baffle


  • Exam I Lect 1-12: Tuesday March 5, 7-9PM, 3081 ECEB
  • Exam II Lect 13-22: Thursday April 16, 7-9PM, 3081 ECEB

The final report:

  • Final written report DUE May 3; final group presentations Wed May 8, 1:30-4:30pm (UIUC Exam schedule)
    • The final report is broken down into 25 topics each worth 1 points, for a total of 25 points.
    • Individuals will be given points for their role in the presentation (up to 5 points each).
    • Up to 5 points of extra credit will be given to the team, if the report is properly formatted (e.g., using LaTeX with high quality figures and equations, etc.).
  • Each person should submit a copy of the final report, with a 1 page personal statement your role in the project, along with the role the other team members (i.e., include self- and team-evaluations).

Final grade distribution:

  • The final grades are computed as follows: Each homework counted for 5 points (25). The two exams were each worth 25 points, for a total of 50 points. The lab project is worth 25 points. This adds to 100 points.

Notes and References

  • Carlin Network postulates pdf
  • Conversion tables for 2-ports (page 1) and ABCD tables from Pipes (pages 2-3): pdf
  • Short table of various Fourier Transforms pdf

General interest

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