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Opening materials

.1 Preface

Once upon a time I went to McGill University to try to get into the Master’s program in sound recording at the Faculty of Music. In order to accomplish this task, students are required to do a “qualifying year” of introductory courses (although it felt more like obstacle courses...) to see who really wants to get in the program. Looking back, there is no question that I learned more in that year than in any other single year of my life. In particular, two memories stand out.

One was my professor – a guy named Peter Cook who now works at the CBC in Toronto as a digital editor. Peter is one of those teachers who doesn’t know everything, and doesn’t pretend to know everything – but if you ask him a question about something he doesn’t understand, he’ll show up at the next week’s class with a reading list where the answer to your question can be found. That kind of enthusiasm in a teacher cannot be replaced by any other quality. I definitely wouldn’t have gotten as much out of that year without him. A good piece of advice that I recently read for university students is that you don’t choose courses, you choose professors.

The second thing was a book by John Woram called the Sound Recording Handbook (the 1989 edition). This book not only proved to be the most amazing introduction to sound recording for a novice idiot like myself, but it continued to be the most used book on my shelf for the following 10 years. In fact, I was still using it as a primary reference when I was studying for my doctoral comprehensives 10 years later. Regrettably, that book is no longer in print – so if you can find a copy (remember – the 1989 edition... no other...) buy (or steal) it and guard it with your life.

Since then, I have seen a lot of students go through various stages of becoming a recording engineer at McGill and in other places and I’ve lamented the lack of a decently-priced but academically valuable textbook for these people. There have been a couple of books that have hit the market, but they’re either too thin, too full of errors, too simplistic or too expensive. (I won’t name any names here, but if you ask me in person, I’ll tell you...)

This is why I’m writing this book. From the beginning, I intended it to be accessible to anyone that was interested enough to read it. I can’t guarantee that it’s completely free of errors – so if you find any, please let me know and I’ll make the appropriate corrections as soon as I can. The tone of this book is pretty colloquial – that’s intentional – I’m trying to make the concepts presented here as accessible as possible without reducing the level of the content, so it can make a good introduction that covers a lot of ground. I’ll admit that it doesn’t make a great reference because there are too many analogies and stories in here – essentially too low a signal to noise ratio to make a decent book for someone that already understands the concepts.

Note that the book isn’t done yet – in fact, in keeping with everything else you’ll find on the web, it will probably never be finished. You’ll find many places where I’ve made notes to myself on what will be added where. Also, there’s a couple of explanations in here that don’t make much sense – even to me... so they’ll get fixed later. Finally, there are a lot of references missing. These will be added in the next update – I promise...

If you think that I’ve left any important subjects out of the Table of Contents, please let me know by email at

.2 Thanks

There are a lot of people to thank for helping me out with this project. I have to start with a big thanks to Peter Cook for getting me started on the right track in the first place. To Wieslaw Woszczyk for allowing me to teach courses at McGill back when I was still just a novice idiot – the best way to learn something is to have to teach it to someone else. To Alain Terriault, Gilbert Soulodre and Michel Lavoie for answering my dumb questions about electronics when I was just starting to get the hang of exactly what things like a capacitor or an op amp do in a circuit. To Brian Sarvis and Kypros Christodoulides who were patient enough to put up with my subsequent dumb questions regarding what things like diodes and transistors do in a circuit. To Jason Corey for putting up with me running down many a wrong track looking for answers to some of the questions found in here. To Mark Ballora for patiently answering questions about DSP and trying (unsuccessfully) to get me to understand Shakespeare. Finally to Philippe Depalle – once upon a time I was taking a course in DSP for dummies at McGill and, about two-thirds of the way through the semester, Philippe guest-taught for one class. In that class, I wound up taking more notes than I had for all classes in the previous part of the semester combined. Since then, Philippe came to be a full-time faculty at McGill and I was lucky enough to have him as a thesis advisor.

I also have to thank a number of people who have proofread some of the stuff you’ll find here and have offered assistance and corrections – either with or without being asked. In alphabetical order, these folks are Ronny Andersson, Bruce Bartlett, Peter Cook, Jakob Dyreby, Goran Finnberg, John La Grou, Brian Madsen, George Massenburg, Gert Munch, Bert Noeth, Ray Rayburn, Eberhard Sengpiel, Greg Simmons and Rowan Williams. One person in this group who deserves a special thanks is Maarten Laandzaat. Maarten read the entire book and sent me pages and pages of corrections and suggestions – he was as close to an editor as I’ll ever have for this thing...

Also on the list of thanks are people who have given permission to use their materials. Thanks to Claudia Haase and Thomas Lischker at RTW Radio-Technische ( for their kind permission to use graphics from their product line for the section on levels and meters. Also to George Massenburg ( for permission to duplicate a chapter from the GML manual on equalizers that I wrote for him.

There are also a large number of people who have emailed me, either to ask questions about things that I didn’t explain well enough the first time, or to make suggestions regarding additions to the book. I’ll list those people in a later update of the text – but thanks to you if you’re in that group.

Finally, thanks to Jonathan Sheaffer and The Jordan Valley Academic College ( for hosting the space to put this file back when it was a growing (and still free) online book. Now that I’m charging money for it, I can pay for my own bandwidth.

.3 Autobiography

Just in case you’re wondering “Who does this guy think he is?” I’ll tell you... This is the bio I usually send out when someone asks me for one. It’s reasonably up-to-date.

Originally from St. John’s, Newfoundland, Geoff Martin completed his Bachelor of Music in pipe organ at Memorial University of Newfoundland in 1990. He is a graduate of McGill University’s Masters of Music in Sound Recording and, in 2001, he completed his doctoral research in which he developed a method of using digital signal processing to simulate reflections from quadratic residue diffusers for multichannel acoustic environments.

Following completion of his doctorate, Geoff was a Faculty Lecturer for McGill’s Music Technology area, where he taught courses in new media, electronics, and electroacoustics. In addition, he was a member of the development team for McGill’s new Centre for Interdisciplinary Research in Music Media and Technology (CIRMMT). He taught electroacoustic music composition and conducted the contemporary music ensemble at the University of Ottawa. He has also been a regular member of the visiting faculty in the Music and Sound Department at the Banff Centre for the Arts in Alberta, Canada. In 2002, he was hired to work in the Automotive Audio division of Bang & Olufsen a/s in Denmark where he designed the audioflow and sound for the award-winning Advanced Sound System for the Audi A8. He continues to work at Bang & Olufsen in the acoustics R & D department where he is the Tonmeister and Technology Specialist in Sound Design.

Geoff has been a member of the Audio Engineering Society (AES) since 1990 and served on the executive for the Montreal Student Chapter for two years. He has published and presented numerous papers on microphone techniques, multichannel audio and virtual acoustics. In addition, he has been an invited presented to many AES conferences, speaking on subjects including recording studio practices, signal processing and automotive audio. Geoff served as the Papers Chair for the 24th International Conference of the AES titled ”Multichannel Audio: The New Reality” held at The Banff Centre. He was the chair of the Technical Committee on Microphones and Applications and was a member of the review board for the Journal of the AES.

He is very happily married, and he and lives in western Denmark with his wife and two sons.


Figure 1: What I look like these days.

.4 Recommended Reading

There are a couple of books that I would highly recommend, either because they’re full of great explanations of the concepts that you’ll need to know, or because they’re great reference books. Some of these aren’t in print any more

.4.1 General Information

Ballou, G., ed. (1987) Handbook for Sound Engineers: The New Audio Cyclopedia, Howard W. Sams & Company, Indianapolis.

Rane’s online dictionary of audio terms at

.4.2 Sound Recording

Woram, John M. (1989) Sound Recording Handbook, Howard W. Sams & Company, Indianapolis. (This is the only edition of this book that I can recommend. I don’t know the previous edition, and the subsequent one wasn’t remotely as good.)

Eargle, John (1986) Handbook of Recording Engineering, Van Nostrand Reinhold, New York.

Rumsey, Francis (2001) Spatial Audio, Focal Press, Oxford

.4.3 Analog Electronics

Jung, Walter G., IC Op-Amp Cookbook, Prentice Hall Inc.

Gayakwad, Ramakant A., (1983) Op-amps and Linear Integrated Circuit Technology, Prentice-Hall Inc.

.4.4 Psychoacoustics

Moore, B. C. J. (1997) An Introduction to the Psychology of Hearing, Academic Press, San Diego.

Blauert, J. (1997) Spatial Hearing: The Psychophysics of Human Sound Localization, MIT Press, Cambridge, Revised Edition.

Bregman, A. S. (1990) Auditory Scene Analysis : The Perceptual Organization of Sound, MIT Press. Cambridge.

Zwicker, E., & Fastl, H. (1999) Psychoacoustics: Facts and Models, Springer, Berlin.

.4.5 Acoustics

Morfey, C. L. (2001). Dictionary of Acoustics, Academic Press, San Diego.

Kinsler L. E., Frey, A. R., Coppens, A. B., & Sanders, J. V. (1982) Fundamentals of Acoustics, John Wiley & Sons, New York, 3rd edition.

Hall, D. E. (1980) Musical Acoustics: An Introduction, Wadsworth Publishing, Belmont.

Kutruff, K. H. (1991) Room Acoustics, Elsevier Science Publishers, Essex.

.4.6 Digital Audio and DSP

Roads, C., ed. (1996) The Computer Music Tutorial, MIT Press, Cambridge.

Strawn, J., editor (1985). Digital Audio Signal Processing: An Anthology, William Kaufmann, Inc., Los Altos.

Smith, Steven W. The Scientist and Engineers Guide to Digital Signal Processing (

Steiglitz, K. (1996) A DSP Primer : With Applications to Digital Audio and Computer Music, Addison-Wesley, Menlo Park.

Zölzer, U. (1997) Digital Audio Signal Processing, John Wiley & Sons, Chichester.

Anything written by Julius Smith

.4.7 Electroacoustic Measurements

Mezler, Bob (1993) Audio Measurement Handbook, Audio Precision, Beaverton (available at a very reasonable price from

Anything written by Julian Dunn

.5 Symbols and Abbreviations

Symbol    Meaning

A Amperes (Amps)

AC Alternating current

AES Audio Engineering Society

AES∕EBU IEC 958 Type 1 protocol for digital audio transmission

AIFF Audio interchange file format

AM Amplitude modulation

B Magnetic flux density

BW Frequency bandwidth

c2 Chi-Square

CMRR Common mode rejection ratio

dB decibel

DC Direct current

DFT Discrete Fourier transform

DRF Directivity factor of a microphone

DSF Distance factor of a microphone

DSP Digital signal processing

EFM Eight-to-Fourteen modulation

EIN Equivalent input noise

EMI Electromagnetic interference

f Frequency

fc Centre frequency

fcentre see fc

FFT Fast Fourier transform

FIR Finite impulse response

FM Frequency modulation

H Henries

H Magnetic coercivity

Hz Hertz (cycles per second)

HRT F Head-related transfer function

i Current

I Sound intensity

IACC Interaural cross correlation

IIR Infinite impulse response

IMD Intermodulation distortion

j   ---
√ - 1

LSB Least significant bit

m Metres

MLS Maximum length sequence

MOA Method of Adjustment

MOL Maximum output level

MSB Most significant bit

p Pressure

P Power

PDF Probability Distribution Function

pi Incident pressure wave

pr Reflected pressure wave

pt Transmitted pressure wave


Q Filter quality

Q1 First quartile

Q2 Second quartile

Q3 Third quartile

r Resistance

R Pressure reflection coefficient

REE Random energy efficiency of a microphone

RER Random energy response of a microphone

RMS Root mean square

RPDF Rectangular probability distribution function

RT 60 Reverberation time

s Standard deviation

s2 Variance

sxy Covariance of x and y

sx Standard deviation of x

sec Seconds

SNR Signal to Noise Ratio

S∕NR Signal to Noise Ratio

S-PDIF Sony-Philips digital interface format (IEC 958 Type 2)

T Pressure transmission coefficient

T HD Total harmonic distortion

T HD+N Total harmonic distortion plus Noise

T PDF Triangular probability distribution function

u Particle velocity

ui Incident particle velocity

ur Reflected particle velocity

ut Transmitted particle velocity

V Volts

W Watts

Wb Webers

X Sample mean

z Impedance

α Absorption coefficient

α Average absorption coefficient

λ Wavelength

μ Magnetic permeability

τ Time constant

ω Radian frequency

Ω Ohm (Electrical)