Sound reproduction : the acoustics and psychoacoustics of loudspeakers and rooms

Cover
Title
Copyright
Contents
Acknowledgments
Introduction
1 Sound Production vs. Sound Reproduction
	1.1 Live Classical Music Performances—Sound Production
	1.2 Live Popular Music Performances—Sound Production
	1.3 Reproduced Sound—The Audio Industry
	1.4 Preserving the Art—The Circle of Confusion
	1.5 Music and Movies—The State of Affairs
	1.6 The Role of Loudspeakers and Rooms
	1.7 Human Adaptation, a Reality That Cannot Be Ignored
	1.8 Human Suggestibility
2 A Scientific Perspective on Audio
	2.1 Requirements for Scientific Investigations
3 Subjective Measurements—Turning Opinion into Fact
	3.1 Is Blind Listening Necessary?
	3.2 Hearing Ability and Listener Performance
	3.3 Stress and Strain
	3.4 How Many Channels?
	3.5 Controlling the Variables in Subjective Evaluations
		3.5.1 Controlling the Physical Variables
			3.5.1.1 The Listening Room—Making Tests Blind
			3.5.1.2 Real-Time Loudspeaker Comparison Methods
			3.5.1.3 Binaural Record/Replay Loudspeaker Comparisons
			3.5.1.4 Listener Position and Seating
			3.5.1.5 Relative Loudness
			3.5.1.6 Absolute Loudness—Playback Sound Levels
			3.5.1.7 Choosing Program Material
			3.5.1.8 Power Amplifiers, Wire and So Forth
		3.5.2 Controlling the Psychological Variables
			3.5.2.1 Knowledge of the Products
			3.5.2.2 Familiarity with the Program
			3.5.2.3 Familiarity with the Room
			3.5.2.4 Familiarity with the Task
			3.5.2.5 Listening Aptitude and Training
			3.5.2.6 Culture, Age and Other Biases
			3.5.2.7 Hearing Ability
			3.5.2.8 Listener Interaction
			3.5.2.9 Recognition
		3.5.3 How to Do the Test
			3.5.3.1 Is It Preference or Accuracy That Is Evaluated?
4 The Perceptual and Physical Dimensions of Sound
	4.1 The Frequency Domain
	4.2 The Amplitude Domain
	4.3 Amplitude and Frequency Together: Frequency Response
	4.4 Amplitude and Frequency Together: Equal-Loudness Contours
		4.4.1 Loudness Controls and Tone Controls—Do They Work, Are They Necessary?
	4.5 The Boundaries of What We Can Hear
		4.5.1 What Is Acceptable Background Noise?
	4.6 Linear Distortions: Amplitude and Phase vs. Frequency
		4.6.1 Spectral Tilt
		4.6.2 Resonances Viewed in Frequency and Time
		4.6.3 Finding and Fixing Resonances
		4.6.4 A Persistent Problem: Differentiating between Evidence of Resonances and Acoustical Interference
		4.6.5 Critical Bands, ERBNs and the “Resolution” of the Hearing System
	4.7 Amplitude, Frequency and Time Together: Waterfall Diagrams
	4.8 Phase and Polarity—Do We Hear Waveforms?
		4.8.1 The Audibility of Phase Shift and Group Delay
		4.8.2 Phase Shift at Low Frequencies: A Special Case
		4.8.3 The Audibility of Absolute Polarity—Which Way Is “Up”?
	4.9 Non-linear Distortion
	4.10 Wavelength, the Key to Understanding Much in Audio
		4.10.1 Loudspeaker Directivity
		4.10.2 Room Resonance Basics
		4.10.3 Resistive/Porous Absorbers and Membrane/Diaphragmatic Absorbers
		4.10.4 Diffusers and Other Sound-Scattering Devices
5 Characterizing Loudspeakers—Can We Describe What Is Good?
	5.1 The Wisdom of the Ancients
	5.2 Identifying the Important Variables—What Do We Measure?
	5.3 Anechoic Measurements—The Spinorama Evolves
	5.4 Total Sound Power as a Measured Parameter
	5.5 Why Do We Measure What We Do? Are There Better Ways?
	5.6 Predicting Room Curves from Anechoic Data—An Exercise in Curve Matching
		5.6.1 A Message about Sound Absorption and Scattering
		5.6.2 Why Do We Care about Room Curves?
	5.7 Closing the Loop: Predicting Listener Preferences from Measurements
		5.7.1 The Olive Experiments—Part One
		5.7.2 The Olive Experiments—Part Two
		5.7.3 The Olive Experiments—Part Three
	5.8 Loudspeaker Resonances—Detection and Remedies
	5.9 Summary and Discussion
6 Loudspeaker/Room Systems—An Introduction
	6.1 One Room, Two Sound Fields—The Transition Frequency
	6.2 A Brief History of Loudspeaker/Room Interactions
	6.3 Timbral and Spatial Effects Attributable to Rooms
7 Above the Transition Frequency: Acoustical Events and Perceptions
	7.1 The Physical Variables: Early Reflections
		7.1.1 Problems with the Stereo Phantom Center Image
	7.2 The Physical Variables: Loudspeaker Directivity
	7.3 The Physical Variables: Acoustical Surface Treatments
		7.3.1 Absorbers
		7.3.2 Engineered Surfaces and Other Sound Scattering/Diffusing Devices
	7.4 Subjective Evaluations in Real-World Situations
		7.4.1 Side Wall Treatment: Reflecting or Absorbing—Kishinaga et al. (1979)
		7.4.2 The Effect of Loudspeaker Directivity—Toole (1985)
		7.4.3 Loudspeaker Directivity and Wall Treatment Together—Choisel (2005)
		7.4.4 The Nature of the Sound Field—Klippel (1990)
		7.4.5 Observations of an Audio Enthusiast—Linkwitz (2007)
		7.4.6 Observations of an Audio Enthusiast—Toole (2016)
		7.4.7 Floor Reflections: A Special Case?
	7.5 Professional Listening vs. Recreational Listening
		7.5.1 Hearing Loss Is a Major Concern
		7.5.2 Discussion
	7.6 Perceptual Effects of Room Reflections
		7.6.1 Adaptation and Perceptual Streaming
		7.6.2 The Effects of Rooms on Loudspeaker Sound Quality
		7.6.3 The Effect of Rooms on Speech Intelligibility
		7.6.4 Sound Localization in Reflective Spaces— The Precedence (Haas) Effect
		7.6.5 Bringing the Precedence Effect into the Real Acoustical World
			7.6.5.1 Ceiling vs. Wall Reflections
			7.6.5.2 Real vs. Phantom Images
			7.6.5.3 Speech vs. Various Musical Sounds
	7.7 Meaningful Measurements of Reflection Amplitudes
8 Below the Transition Frequency: Acoustical Events and Perceptions
	8.1 The Basics of Room Resonances and Standing Waves
		8.1.1 Optimizing Room Dimensions—Does an “Ideal” Room Exist?
		8.1.2 Are Non-rectangular Rooms the Answer?
	8.2 Solutions for the Real World
		8.2.1 Deliver Energy to the Modes and Dissipate Some of That Energy with Absorbers
		8.2.2 Deliver Energy to the Modes and Reduce the Coupling of That Energy to the Listener by Optimizing the Listening Location—“Positional” Equalization
		8.2.3 Reduce the Energy Delivered to a Bothersome Mode by Optimizing the Loudspeaker/Subwoofer Location
		8.2.4 Reduce the Energy Delivered to a Bothersome Mode by Using Parametric Equalization
		8.2.5 Reduce the Energy Delivered to a Bothersome Mode by Using Simple Mode-Manipulation Techniques
		8.2.6 Selective Mode Activation in Rectangular Rooms Using Passive Multiple-Subwoofer Mode Manipulation
		8.2.7 Mode Manipulation for Rectangular Rooms Using Multiple Subwoofers and Signal Processing
		8.2.8 Mode Manipulation for Any Room Using Multiple Subwoofers and Signal Processing: Sound Field Management (SFM)
		8.2.9 Revisiting Room Resonances in Time and Space
	8.3 Do We Hear the Spectral Bump, the Temporal Ringing or Both?
	8.4 Stereo Bass: Little Ado about Even Less
	8.5 Bass Management Makes It All Possible
	8.6 Summary and Discussion
9 Adjacent-Boundary and Loudspeaker Mounting Effects
	9.1 The Effects of Solid Angles on the Radiation of Sound by Omnidirectional Sources
	9.2 Classic Adjacent-Boundary Effects
		9.2.1 Alleviating Adjacent-Boundary Effects
	9.3 Loudspeaker Mounting Options and Effects
		9.3.1 An Example of Adjacent-Boundary Interference
	9.4 “Boundary-Friendly” Loudspeaker Designs
	9.5 Array Loudspeakers—Other Ways to Manipulate Boundary Interactions
	9.6 Listeners Also Have Boundaries
10 The Sound Fields in Sound Reproduction Spaces
	10.1 Reverberation
		10.1.1 Measuring Reverberation Time
		10.1.2 Calculating Reverberation Time
		10.1.3 Is There a More Useful Metric for Our Purposes?
	10.2 Diffusion
	10.3 Direct Sound and Early Reflections
	10.4 Near and Far Fields of Rooms—Sound Level vs. Distance
	10.5 Near and Far Fields of Sound Sources
		10.5.1 Point Sources and Real Loudspeakers
		10.5.2 Line Sources
	10.6 Air Absorption at High Frequencies
	10.7 Screen Loss in Home Theaters and Cinemas
	10.8 The Directivities of Common Sound Sources
11 Sound in Cinemas
	11.1 The Closed Loop of Cinema Sound
	11.2 Sound Fields in Cinemas
		11.2.1 A Loudspeaker in a Cinema
		11.2.2 Adding a Screen and Applying the X-curve
	11.3 The Origins of the X-curve
	11.4 A Recent Study Adds Confirmation and Clarity
	11.5 Flat, Direct Sound Is an Enduring Favorite
	11.6 Alternative Targets—Is It Time to Move On?
		11.6.1 Compatibility with the Rest of the Audio World
		11.6.2 Compatibility within the Cinema World
	11.7 The Effects of Room Size and Seats
	11.8 Cinema Sound—Where to Next?
12 Sound in Home Listening Rooms, Home Theaters and Recording Control Rooms
	12.1 Good Sound Starts with Good Loudspeakers
		12.1.1 Typical Loudspeaker Specifications—Part of the Problem
	12.2 Loudspeakers in Small Rooms: The Meaning of Room Curves
		12.2.1 The Effect of Loudspeaker Directional Configuration
		12.2.2 Looking Back 42 Years: the Møller/Brüel and Kjaer Experiments
		12.2.3 Room Curves and Equalization
	12.3 Subjective Preferences for Sound Spectra in Listening Rooms
	12.4 Dialog Intelligibility in Home Theaters
	12.5 Recording Control Rooms
		12.5.1 Old-School Monitoring
		12.5.2 Modern Monitoring
13 A Rational Approach to Designing, Measuring and Calibrating Sound Reproducing Systems
	13.1 Low Frequencies—The Universal Problem
	13.2 Sound above the Transition Frequency
		13.2.1 Thirty Years—Some Things Change, Some Don’t
		13.2.2 The Wrong Room Curve Target?
		13.2.3 “Room Correction” and “Room Equalization” Are Misnomers
		13.2.4 Automotive Audio
		13.2.5 Headphones
		13.2.6 Cinemas
	13.3 Is There a Common Factor—A Generalizable Target?
14 Measurement Methods
	14.1 Alternative Views of Frequency Response
		14.1.1 Prediction of the Direct Sound and Room Curves from Anechoic Data
		14.1.2 In-Situ Measurement of the Direct Sound
		14.1.3 The Steady-State Room Curve
	14.2 Measures of Loudness and System-Level Calibrations
		14.2.1 Evaluating Relative Program Loudness Levels
		14.2.2 Multichannel Sound System-Level Calibration
		14.2.3 The Effect of Propagation Distance— A Side-Channel Challenge
	14.3 Measurement Microphones
15 Multichannel Audio
	15.1 A Few Definitions
	15.2 The Birth of Multichannel Audio
	15.3 Stereo—An Important Beginning
		15.3.1 Loudspeakers as Stereo Image Stabilizers
	15.4 Quadraphonics—Stereo Times Two
	15.5 Multichannel Audio—Cinema to the Rescue
	15.6 Multichannel Audio Comes Home
		15.6.1 THX Embellishments
	15.7 How Many Loudspeakers and Where?
		15.7.1 Optimizing the Delivery of “Envelopment”
		15.7.2 Summary
	15.8 Surround System Layouts
		15.8.1 Loudspeaker Directivity Requirements
		15.8.2 Mission-Oriented Acoustical Treatments
		15.8.3 Surround Loudspeaker Options
	15.9 The Ambisonics Alternative
	15.10 Upmixer Manipulations: Creativity at Work
	15.11 Multichannel Audio Goes Digital, Discrete and Compressed
	15.12 Three-Dimensional Sound—Immersive Audio
		15.12.1 The Perception of Elevation
16 Loudspeakers and Power Amplifiers
	16.1 Consequences of Loudspeaker Impedance Variations
	16.2 The Damping Factor Deception
	16.3 Loudspeaker Sensitivity Ratings and Power Amplifiers
	16.4 The Audibility of Clipping
17 Hearing Loss and Hearing Conservation
	17.1 Occupational Noise Exposure Limits
	17.2 Non-occupational Noise Exposure
	17.3 Binaural Hearing Is Also Affected
	17.4 Some Obsession Can Be a Good Thing
18 Fifty Years of Progress in Loudspeaker Design
	18.1 My Introduction to the Real World
	18.2 Two Decades of Domestic Loudspeakers
	18.3 Some Early Professional Monitor Loudspeakers
		18.3.1 A “Toole” Monitor Loudspeaker
	18.4 Looking Around and Looking Ahead
	18.5 The End
References
Index