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  • Instructor: Jont Allen (jontalle@illinois.edu); Office hours: By Appointment
  • TA: Sarah Robinson (srrobin2@illinois.edu); Office hours: Mondays 2:30-3:30pm & By Appointment (2137 Beckman Institute)
  • Class Time: 12:30 T/R (Tues/Thur), Place: 3081-ECEB: ECE, UIUC, UI Calendar
  • Lectures will be presented on Tuesdays & Labs on most Thursdays (see schedule). Labs will be completed in small teams of 3-5 students.
  • Text: Beranek & Mellow (2012) UIUC-ebook; Buy; Browse; Reference text: Electroacoustics (pdf) TOC, Preface, Preface1
    • 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 (a-e); Links to these assignments are available in the Daily Schedule below.
  • Labs (Section 1: Thursdays 12:30-1:50pm (class time); Section 2: Fridays 9:30-10:50am; Labs do not occur every week, please check the schedule. If there is no lab, there will be a regular Thursday lecture) groups
    • Lab manual (check back for regular updates each time we have a new lab). In preparation for each lab, please read the corresponding section of the manual BEFORE coming to lab!
    • Lab location: 5072 ECE (you have ICard access). Four network-analyzers (MU boxes) in cabinet on right
      NOTE: This lab is OCCUPIED Monday 3-5pm, Tuesday 2-5pm, Wednesday 1-5pm, Thursday 2-5pm, and Friday 12-5pm by ECE 420 students, who have priority during these times (their labs and office hours).
    • Software for Labs: G7-software (runs in Matlab or Octave); All 403 Files
    • Tools: MATLAB, Octave, playrec: alternate audio software, Github playrec; Latex
  • Exam 1, Exam2, Final Report: Format for final report pdf, LaTeX example: zip
  • This week's schedule

If the LaTeX math does not render properly (e.g., Chrome), update the browser extension: google store

Spring 2017 Daily Schedule

Part I: Basic Acoustics (Ch 1) (3 Lect)
M 1/16 MLK Day
1 3 T 1/17 *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 Ch 1, p. 1-17
2 R 1/19 *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 Ch 2, p. 21-29 (Wave Equation)
3 4 T 1/24 *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. 37-48
*Homework A (Discuss on Lect 5; due on Tues 2/7 (Lect 7))
Part II: Circuit Analysis (Ch 3-4) (5 Lect, 1 Lab)



R 1/26 *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? pdf)
*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
5 5 T 1/31 *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 2/2 *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: Kim et al, Carlin;
7 6 T 2/7 *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 on Tues 2/21 (Lect 11))
*Read Ch 3, p.106-118

R 2/9 *Lab 1 (5072 ECEB): Setup of hardware; Learn how to make impedance measurements: Circuit Schematic
*Install g7play software package
*Construct circuit board to measure loudspeaker impedance, and debug it.
*Read Lec 36, pp 87-90: An Invitation ... (pdf)
Part III: Electrodynamic Loudspeakers (Ch 6)
9 7 T 2/14 *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 Feb 21, in 1 week)
*Read: Lab manual

R 2/16 *Lab 2 (5072 ECEB):
*Measurement of 2-port RC (example from HWb) (EvalResp.m)
*Read Ch 3, p. ??
11 8 T 2/21 *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 on Thurs 3/2 (Lect 14)), SpeakerModel.m
*Read Ch 3, p. 94-96

R 2/23 *Lab 3 (5072 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+ Lab 3 of Lab manual
13 9 T 2/28 *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 ??
14 R 3/2 *Lect: Sarah Robinson: Thevenin & Norton parameters of a loudspeaker: \(P_0(f), U_0(f), Z_0(s)\)
*Review for Exam I, which covers Lectures 1-12, HW-A,B,C
*Read ??

15 10 T 3/7 NO class: Exam I Tuesday March 7, @ 7-9PM Room: 3081 ECEB
Part IV: Horns with Viscous & Thermal loss; Reciprocity (6 Lect, 2 Labs)
16 R 3/9 *Lect: Acoustic transmission lines
*Homework D: Acoustics & Transmission Lines (Discuss on Lect 17; due on Tues 3/28 (Lect 19))
*Read ??
3/10-3/11 [Engineering Open House]
17 11 T 3/14 *Lect: Reciprocity calibration of a loudspeaker
*Discuss HW-D
*Read Lab 3-4, p. 14-19

R 3/16 *Lab 4 (5072 ECEB): Reciprocity calibration; verification with a probe microphone (Etymotic Research-7C)
12 M
3/18 Spring Break
19 13 T 3/28 *Lect: Speaker Acoustic Thevenin calibration using 2 or more acoustics loads
*Read: Thevenin model of source

R 3/30 *Lab 5 (5072 ECEB): Speaker Acoustic Thevenin calibration using 2 acoustics loads (Duct tape)
*Homework E (Discuss on Lect 23; due on Tues 4/13 (Lect 24)); Starter files for middle ear simulation (txline.m, gamma.m)
*Read: ABCD for Thevenin source

21 14 T 4/4 *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 4/6 *Lab 6 (5072 ECEB): Measure the speaker radiation impedance \(Z_{rad}(s)\) and compare to the spherical radiator
*Read: Radiation impedance of sphere


15 T 4/11 *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 4/13 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 4/18 NO Class: Exam II Tuesday April 18, @ 7-9PM Room: 3081 ECEB
Part V: Topics in Audio Engineering

26 R 4/20 *Lab 7 (5072 ECEB): Choice of 1) Earbud in ear simulator, 2) Horn baffle, 3) AR-3 Acoustic suspension baffle
*Work on lab report (Example LaTeX)
17 T 4/25 *Lect: Baffling loudspeaker topics
*Read Ch7, p. 289-320
28 R 4/27 *Guest Lecture: Mead Killion CEO Etymotic Research, Elk Grove Village IL
29 18 T 5/2 *Lab; Last class; Open discussion of Lab report content; what you learned this semester
W 5/3 Instruction ends
R 5/4 Reading Day
F 5/5 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 presentation on loudspeakers)
M 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 1/24 (Lect 3), DUE Tues 2/7 (Lect 7): Acoustics and LT/FT
  • HW-B, Assigned 2/7 (Lect 7), DUE Tues 2/21 (Lect 11): T, Z matrix + Transmission line theory
  • HW-C, Assigned 2/21 (Lect 11), DUE Thurs 3/2 (Lect 14): Electrodynamic ABCD model with Gyrator, Motional impedance & \(Z_A(s)\) TL load
  • HW-D, Assigned 3/9 (Lect 16), DUE Tues 3/28 (Lect 19): Horns, reciprocity, Thevenin model of Johnson resistor noise
  • HW-E, Assigned 2/28 (Lect 19), DUE Tues 4/13 (Lect 24): Middle ear model


  • Lab manual
  • Lab 0, Thurs 2/2, 3081 ECEB (Lect 6): a) Define teams; b) Define goals of Labs
  • Lab 1, Thurs 2/9, 5072 ECEB (Lect 8): a) Op-amp circuit construction; b) MU calibraton with a 1 kohm resistor
  • Lab 2, Thurs 2/16, 5072 ECEB (Lect 10): Measure 2-ports: (video) a) RC lowpass (EvalResp.m), b) Twin-Tee notch filter
  • Lab 3, Thurs 2/23, 5072 ECEB (Lect 12): Speaker electrical impedance: a) Loaded, b) Unloaded, c) Compute speaker motional impedance

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

  • Lab 4, Thurs 3/16, 5072 ECEB (Lect 18): Reciprocity calibration with probe mic verification

(syms algebra: RecipCal.m)

  • Lab 5, Thurs 3/30, 5072 ECEB (Lect 20): Thevenin Equivalent circuit via 2 acoustic loads (Duct Tape cavities)
  • Lab 6, Thurs 4/6, 5072 ECEB (Lect 22): Measure speaker acoustic radiation impedance \(Z_{rad}\)
  • Lab 7, Thurs 4/20, 5072 ECEB (Lect 26): 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 7, 7-9PM, 3081 ECEB
  • Exam II Lect 13-22: Tuesday April 18, 7-9PM, 3081 ECEB

The final report:

  • Final written report DUE May 5; final group presentations Monday May 8, 1:30-4:30pm (UIUC policy)
    • 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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