Digital Sound & Music: Concepts, Applications, and Science

This book, originally developed under National Science Foundation grant support, was written to bridge academic disciplines and areas of practice that include music production, audio engineering for theatre and film, and computer science. Apart from the first and the last chapters, each chapter is divided into three sections. The first section covers general concepts, the second discusses applications, and the third delves into the mathematics and algorithms that underpin digital audio processing.

It is not intended that a single course would cover all the material in this book. Rather, portions of the book could be used in college-level courses such as the following:

•          theatre or film sound design and production
•          digital music production
•          a course covering sound in a New Media or Digital Media or Digital Arts program (particularly in programs that are interdisciplinary between computer science and music)
•          a computer science course introducing digital signal processing
•          a computer science course which engages students in programming through audio applications

The special value of this book is that it provides a broad context for students. In academic programs that emphasize applications, students are still able to "look under the hood" to have a deeper understanding of audio processing at a lower level of abstraction. For students of computer science, physics, or mathematics, the relationship between science and applications provides interest and motivation.

The book also serves as a reference for anyone interested in digital audio processing. This includes hobbyists, those who are "self-taught" in music production, and even those already in the audio processing or music production industry who want a deeper understanding of their art and craft.

This book is available in an online format at http://digitalsoundandmusic.com/.

Table of Contents:

CHAPTER 1: GETTING READY
1.1 SOUNDS LIKE FUN!
1.2 HOW THIS BOOK IS ORGANIZED
1.3 A BRIEF HISTORY OF DIGITAL SOUND
1.4 BASIC TERMINOLOGY
1.5 SETTING UP YOUR WORK ENVIRONMENT
1.6 LEARNING SUPPLEMENTS
1.7 WHERE TO GO FROM HERE
1.8 REFERENCES

CHAPTER 2: SOUND WAVES
2.1 CONCEPTS
    2.1.1 Sound Waves, Sine Waves, and Harmonic Motion
    2.1.2 Properties of Sine Waves
    2.1.3 Longitudinal and Transverse Waves
    2.1.4 Resonance
    2.1.5 Digitizing Sound Waves
2.2 APPLICATIONS
    2.2.1 Acoustics
    2.2.2 Sound Synthesis
    2.2.3 Sound Analysis
    2.2.4 Frequency Componentsof Non-Sinusoidal Waves
    2.2.5 Frequency, Impulse, and Phase Response Graphs
    2.2.6 Ear Testing and Training
2.3 SCIENCE, MATHEMATICS, AND ALGORITHMS
    2.3.1 Modeling Sound in Max
    2.3.2 Modeling Sound Waves in Pure Data (PD)
    2.3.3 Modeling Sound in MATLAB
    2.3.4 Reading and Writing WAV Files in MATLAB
    2.3.5 Modeling Sound in Octave
    2.3.6 Transforming from One Domain to Another
    2.3.7 The Discrete Fourier Transform and Its Inverse
    2.3.8 The Fast Fourier Transform (FFT)
    2.3.9 Applying the Fourier Transform in MATLAB
    2.3.10 Windowing the FFT
    2.3.11 Windowing Functions to Eliminate Spectral Leakage
    2.3.12 Modeling Sound in C++ under Linux
    2.3.13 Modeling Sound in Java

CHAPTER 3: MUSICAL SOUND
3.1 CONCEPTS
    3.1.1 Context
    3.1.2 Tones and Notes
    3.1.3 Music vs. Noise
    3.1.4 Scales
    3.1.5 Musical Notation
    3.1.6 Musical Composition
    3.1.7 Dynamics and Articulation
3.2 APPLICATIONS
    3.2.1 Piano Roll and Event List Views
    3.2.2 Tablature
    3.2.3 Chord Progression
    3.2.4 Guitar Chord Grid
3.3 SCIENCE, MATHEMATICS, AND ALGORITHMS
    3.3.1 The Mathematics of Music
    3.3.2 Equal Tempered vs. Just Tempered Intervals
    3.3.3 Experimenting with Music in Max
    3.3.4 Experimenting with Music in MATLAB
    3.3.5 Experimenting with Music in C++
    3.3.6 Experimenting with Music in Java

CHAPTER 4: SOUND PERCEPTION AND ACOUSTICS
4.1 CONCEPTS
    4.1.1 Acoustics
    4.1.2 Psychoacoustics
    4.1.3 Objective and Subjective Measures of Sound
    4.1.4 Units for Measuring Electricity and Sound
    4.1.5 Decibels
    4.1.6 Sound Perception
    4.1.7 The Interaction of Sound with its Environment
4.2 APPLICATIONS
    4.2.1 Working with Decibels
    4.2.2 Acoustic Considerations for Live Performances
    4.2.3 Acoustical Considerations for the Recording Studio
4.3 SCIENCE, MATHEMATICS, AND ALGORITHMS
    4.3.1 Deriving Power and Voltage Changes in Decibels
    4.3.2 Working with Critical Bands
        4.3.3 A MATLAB Program for Equal Loudness Contours
    4.3.4 The Mathematics of the Inverse Square Law and PAG Equations
    4.3.5 The Mathematics of Delays, Comb Filtering, and Room Modes

CHAPTER 5: DIGITIZATION
5.1 CONCEPTS
    5.1.1 Analog vs. Digital
    5.1.2 Digitization
    5.1.3 Audio Data Streams and Transmission Protocols
    5.1.4 Signal Path in an Audio Recording System
    5.1.5 CPU and Hard Drive Considerations
    5.1.6 Digital Audio File Types
5.2 APPLICATIONS
    5.2.1 Choosing an Appropriate Sampling Rate
    5.2.2 Input Levels, Output Levels, and Dynamic Range
    5.2.3 Latency and Buff ers
    5.2.4 Word Clock
5.3 SCIENCE, MATHEMATICS, AND ALGORITHMS
    5.3.1 Reading and Writing Audio Files in MATLAB
    5.3.2 Raw Audio Data in C++
    5.3.3 Reading and Writing Formatted Audio Files in C++
    5.3.4 Mathematics and Algorithms for Aliasing
    5.3.5 Simulating Sampling and Quantization in MATLAB
    5.3.6 Simulating Sampling and Quantization in C++
    5.3.7 The Mathematics of Dithering and Noise Shaping
    5.3.8 Algorithms for Audio Companding and Compression

CHAPTER 6: MIDI AND SOUND SYNTHESIS
6.1 CONCEPTS
    6.1.1 The Beginnings of Sound Synthesis
    6.1.2 MIDI Components
    6.1.3 MIDI Data Compared to Digital Audio
    6.1.4 Channels, Tracks, and Patches in MIDI Sequencers
    6.1.5 A Closer Look at MIDI Messages
    6.1.6 Synthesizers vs. Samplers
    6.1.7 Synthesis Methods
    6.1.8 Synthesizer Components
6.2 APPLICATIONS
    6.2.1 Linking Controllers, Sequencers, and Synthesizers
    6.2.2 Creating Your Own Synthesizer Sounds
    6.2.3 Making and Loading Your Own Samples
    6.2.4 Data Flow and Performance Issues in Audio/MIDI Recording
    6.2.5 Non-Musical Applications for MIDI
6.3 SCIENCE, MATHEMATICS, AND ALGORITHMS
    6.3.1 MIDI SMF Files
    6.3.2 Shaping Synthesizer Parameters with Envelopes and LFOs
    6.3.3 Types of Synthesis
    6.3.4 Creating a Block Synthesizer in Max

CHAPTER 7: AUDIO PROCESSING
7.1 CONCEPTS
    7.1.1 It’s All Audio Processing
    7.1.2 Filters
    7.1.3 Equalization
    7.1.4 Graphic EQ
    7.1.5 Parametric EQ
    7.1.6 Reverb
    7.1.7 Flange
    7.1.8 Vocoders
    7.1.9 Autotuners
    7.1.10 Dynamics Processing
7.2 APPLICATIONS
    7.2.1 Mixing
    7.2.2 Applying EQ
    7.2.3 Applying Reverb
    7.2.4 Applying Dynamics Processing
    7.2.5 Applying Special Eff ects
7.3 SCIENCE, MATHEMATICS, AND ALGORITHMS
    7.3.1 Convolution and Time Domain Filtering
    7.3.2 Low-Pass, High-Pass, Bandpass, and Bandstop Filters
    7.3.3 The Z-Transform
    7.3.4 Filtering in the Time and Frequency Domains
    7.3.5 Defi ning FIR and IIR Filters with Z-Transforms, Filter Diagrams, and Transfer Functions
    7.3.6 Graphing Filters and Plotting Zero-Pole Diagrams
    7.3.7 Comb Filters and Delays
    7.3.8 Flanging
    7.3.9 The Digital Signal Processing Toolkit in MATLAB
    7.3.10 Experiments with Filtering: Vocoders and Pitch Glides
    7.3.11 Real-Time vs. Off -Line Processing

CHAPTER 8: GETTING TO WORK
8.1 SOUND FOR ALL OCCASIONS
8.2 WORKFLOW IN SOUND AND MUSIC PRODUCTION
    8.2.1 Workflow in Sound and Music Production
    8.2.2 Pre-production
    8.2.3 Production
    8.2.4 Post-production
    8.2.5 Live Sound