Engineering Noise Control

by Bies, David A.; Hansen, Colin H.

• ISBN13: 9780415267144
• ISBN10: 0415267145
• Edition: 3rd
• Format: Paperback
• Copyright: 2003-09-29
• Publisher: Spon Press

Summary

The third edition ofEngineering Noise Controlhas been thoroughly revised, updated and extended. Each chapter contains new material, much of which is not available elsewhere. The result is a comprehensive discussion of the theoretical principles and concepts of acoustics and noise control, a detailed discussion of the hearing mechanism, noise measuring instrumentation and techniques, noise criteria, sound source characterization and emission, outdoor sound propagation, sound in rooms, sound transmission through partitions, enclosure design, dissipative and reactive mufflers, vibration isolation, equipment sound power emission calculations and active noise cancellation. The book is an excellent text for advanced undergraduate or graduate students of acoustic and noise control, and it also contains the necessary information and prediction techniques that make it an invaluable resource for the practitioner.

Author Biography

David Bies is and Honorary Research Fellow at the University of Adelaide's Department of Mechanical Engineering. He has previously worked as a senior consultant in industry.

Table of Contents

Preface	xvii
Acknowledgements	xx
CHAPTER ONE Fundamentals and basic terminology	1	(53)
1.1 INTRODUCTION	1	(2)
1.2 NOISE-CONTROL STRATEGIES	3	(9)
1.2.1 Sound Source Modification	5	(3)
1.2.2 Control of the Transmission Path	8	(1)
1.2.3 Modification of the Receiver	8	(1)
1.2.4 Existing Facilities	8	(2)
1.2.5 Facilities in the Design Stage	10	(1)
1.2.6 Airborne Versus Structure-borne Noise	11	(1)
1.3 ACOUSTIC FIELD VARIABLES AND THE WAVE EQUATION	12	(8)
1.3.1 Variables	12	(1)
1.3.2 The Acoustic Field	13	(1)
1.3.3 Magnitudes	14	(1)
1.3.4 The Speed of Sound	15	(3)
1.3.5 Dispersion	18	(1)
1.3.6 Acoustic Potential Function and the Wave Equation	19	(1)
1.4 PLANE AND SPHERICAL WAVES	20	(9)
1.4.1 Plane Wave Propagation	20	(4)
1.4.2 Spherical Wave Propagation	24	(3)
1.4.3 Wave Summation	27	(1)
1.4.4 Plane Standing Waves	28	(1)
1.4.5 Spherical Standing Waves	29	(1)
1.5 MEAN SQUARE QUANTITIES	29	(1)
1.6 ENERGY DENSITY	30	(1)
1.7 SOUND INTENSITY	31	(5)
1.7.1 Definitions	32	(2)
1.7.2 Plane Wave and Far Field Intensity	34	(1)
1.7.3 Spherical Wave Intensity	35	(1)
1.8 SOUND POWER	36	(1)
1.9 UNITS	36	(3)
1.10 SPECTRA	39	(5)
1.10.1 Frequency Analysis	41	(3)
1.11 COMBINING SOUND PRESSURES	44	(7)
1.11.1 Coherent and Incoherent Sounds	44	(1)
1.11.2 Addition of Coherent Sound Pressures	45	(1)
1.11.3 Beating	45	(2)
1.11.4 Addition of Incoherent Sounds (Logarithmic Addition)	47	(2)
1.11.5 Subtraction of Sound Pressure Levels	49	(1)
1.11.6 Combining Level Reductions	49	(2)
1.12 IMPEDANCE	51	(1)
1.12.1 Mechanical Impedance, Zm	51	(1)
1.12.2 Specific Acoustic Impedance, Z	51	(1)
1.12.3 Acoustic Impedance, ZA	52	(1)
1.13 FLOW RESISTANCE	52	(2)
CHAPTER TWO The human ear	54	(38)
2.1 BRIEF DESCRIPTION OF THE EAR	54	(10)
2.1.1 External Ear	54	(1)
2.1.2 Middle Ear	55	(1)
2.1.3 Inner Ear	56	(3)
2.1.4 Cochlear Duct or Partition	59	(1)
2.1.5 Hair Cells	60	(1)
2.1.6 Neural Encoding	61	(1)
2.1.7 Linear Array of Uncoupled Oscillators	62	(2)
2.2 MECHANICAL PROPERTIES OF THE CENTRAL PARTITION	64	(13)
2.2.1 Basilar Membrane Travelling Wave	64	(4)
2.2.2 Energy Transport and Group Speed	68	(1)
2.2.3 Un-damping	69	(1)
2.2.4 The Half Octave Shift	70	(4)
2.2.5 Frequency Response	74	(1)
2.2.6 Critical Frequency Band	74	(2)
2.2.7 Frequency Resolution	76	(1)
2.3 NOISE INDUCED HEARING LOSS	77	(1)
2.4 SUBJECTIVE RESPONSE TO SOUND PRESSURE LEVEL	78	(14)
2.4.1 Masking	79	(3)
2.4.2 Loudness	82	(1)
2.4.3 Comparative Loudness and the Phon	83	(3)
2.4.4 Relative Loudness and the Sone	86	(3)
2.4.5 Pitch	89	(3)
CHAPTER THREE Instrumentation for noise measurement and analysis	92	(31)
3.1 MICROPHONES	92	(8)
3.1.1 Condenser Microphone	93	(2)
3.1.2 Piezoelectric Microphone	95	(1)
3.1.3 Pressure Response	96	(1)
3.1.4 Microphone Sensitivity	96	(1)
3.1.5 Field Effects and Calibration	97	(3)
3.2 WEIGHTING NETWORKS	100	(2)
3.3 SOUND LEVEL METERS	102	(2)
3.4 GRADES OF SOUND LEVEL METER	104	(1)
3.5 SOUND LEVEL METER CALIBRATION	104	(1)
3.5.1 Electrical Calibration	104	(1)
3.5.2 Acoustical Calibration	104	(1)
3.6 NOISE MEASUREMENTS USING SOUND LEVEL METERS	105	(2)
3.6.1 Microphone Mishandling	105	(1)
3.6.2 Sound Level Meter Amplifier Mishandling	105	(1)
3.6.3 Microphone and Sound Level Meter Response Characteristics	106	(1)
3.6.4 Background Noise	106	(1)
3.6.5 Wind Noise	106	(1)
3.6.6 Temperature	106	(1)
3.6.7 Humidity and Dust	107	(1)
3.6.8 Reflections From Nearby Surfaces	107	(1)
3.7 TIME-VARYING SOUND	107	(1)
3.8 NOISE LEVEL MEASUREMENT	108	(2)
3.9 STATISTICAL ANALYSERS	110	(1)
3.10 NOISE DOSIMETERS	110	(1)
3.11 TAPE RECORDING OF NOISE	111	(2)
3.12 SPECTRUM ANALYSERS	113	(1)
3.13 INTENSITY METERS	114	(7)
3.13.1 Sound Intensity by the p-u Method	115	(1)
3.13.2 Sound Intensity by the p-p Method	116	(3)
3.13.3 Frequency Decomposition of the Intensity	119	(4)
3.13.3.1 Direct Frequency Decomposition	119	(1)
3.13.3.2 Indirect Frequency Decomposition	119	(2)
3.14 ENERGY DENSITY SENSORS	121	(2)
CHAPTER FOUR Criteria	123	(51)
4.1 INTRODUCTION	123	(5)
4.1.1 Noise Measures	124	(4)
4.1.1.1 A-weighted Equivalent Continuous Noise Level, LAeq	124	(1)
4.1.1.2 A-weighted Sound Exposure	124	(1)
4.1.1.3 A-weighted Sound Exposure Level, LAE or SEL	125	(1)
4.1.1.4 Day-Night Average Sound Level, Ldn or DNL	126	(1)
4.1.1.5 Community Noise Equivalent Level, Lden or CNEL	126	(1)
4.1.1.6 Effective Perceived Noise Level, LPNE	127	(1)
4.1.1.7 Other Descriptors	128	(1)
4.2 HEARING LOSS	128	(3)
4.2.1 Threshold Shift	128	(1)
4.2.2 Presbyacusis	129	(1)
4.2.3 Hearing Damage	130	(1)
4.3 HEARING DAMAGE RISK	131	(13)
4.3.1 Requirements for Speech Recognition	132	(1)
4.3.2 Quantifying Hearing Damage Risk	132	(2)
4.3.3 International Standards Organization Formulation	134	(3)
4.3.4 Alternative Formulations	137	(2)
4.3.4.1 Bies and Hansen Formulation	137	(1)
4.3.4.2 Dresden Group Formulation	138	(1)
4.3.5 Observed Hearing Loss	139	(2)
4.3.6 Some Alternative Interpretations	141	(3)
4.4 NEARING DAMAGE RISK CRITERIA	144	(4)
4.4.1 Continuous Noise	144	(1)
4.4.2 Impulse Noise	145	(1)
4.4.3 Impact Noise	146	(2)
4.5 IMPLEMENTING A HEARING CONSERVATION PROGRAM	148	(2)
4.6 SPEECH INTERFERENCE CRITERIA	150	(2)
4.6.1 Broadband Background Noise	150	(1)
4.6.2 Intense Tones	151	(1)
4.7 PSYCHOLOGICAL EFFECTS OF NOISE	152	(1)
4.7.1 Noise as a Cause of Stress	152	(1)
4.7.2 Effect on Behaviour and Work Efficiency	152	(1)
4.8 AMBIENT NOISE LEVEL SPECIFICATION	152	(13)
4.8.1 Noise Weighting Curves	154	(9)
4.8.1.1 NR Curves	154	(2)
4.8.1.2 NC curves	156	(1)
4.8.1.3 RC curves	157	(2)
4.8.1.4 NCB curves	159	(2)
4.8.1.5 RNC curves	161	(2)
4.8.2 Comparison of Noise Weighting Curves with dB(A) Specifications	163	(1)
4.8.3 Speech Privacy	164	(1)
4.9 ENVIRONMENTAL NOISE LEVEL CRITERIA	165	(4)
4.9.1 A-weighting Criteria	166	(2)
4.9.2 Noise Rating Criteria	168	(1)
4.10 ENVIRONMENTAL NOISE SURVEYS	169	(5)
4.10.1 Measurement Locations	171	(1)
4.10.2 Duration of the Measurement Survey	171	(1)
4.10.3 Measurement Parameters	172	(1)
4.10.4 Noise Impact	172	(2)
CHAPTER FIVE Sound sources and outdoor sound propagation	174	(71)
5.1 INTRODUCTION	174	(1)
5.2 SIMPLE SOURCE	175	(3)
5.2.1 Pulsating Sphere	175	(3)
5.2.2 Fluid Mechanical Monopole Source	178	(1)
5.3 DIPOLE SOURCE	178	(7)
5.3.1 Pulsating Doublet (Far-field Approximation)	179	(3)
5.3.2 Vibrating Sphere	182	(2)
5.3.3 Fluid Mechanical Dipole Source	184	(1)
5.4 QUADRUPOLE SOURCE (FAR-FIELD APPROXIMATION)	185	(3)
5.4.1 Lateral Quadrupole	187	(1)
5.4.2 Longitudinal Quadrupole	187	(1)
5.4.3 Fluid Mechanical Quadrupole Source	187	(1)
5.5 LINE SOURCE	188	(4)
5.5.1 Infinite Line Source	188	(3)
5.5.2 Finite Line Source	191	(1)
5.6 PISTON IN AN INFINITE BAFFLE	192	(8)
5.6.1 Far Field	192	(3)
5.6.2 Near Field On-axis	195	(2)
5.6.3 Radiation Load of the Near Field	197	(3)
5.7 INCOHERENT PLANE RADIATOR	200	(4)
5.7.1 Single Wall	200	(4)
5.7.2 Several Walls of a Building or Enclosure	204	(1)
5.8 DIRECTIVITY	204	(1)
5.9 REFLECTION EFFECTS	205	(3)
5.9.1 Simple Source Near a Reflecting Surface	205	(1)
5.9.2 Observer Near a Reflecting Surface	206	(1)
5.9.3 Observer and Source Both Close to a Reflecting Surface	207	(1)
5.10 REFLECTION AND TRANSMISSION AT A PLANE/TWO MEDIA INTERFACE	208	(9)
5.10.1 Porous Earth	208	(1)
5.10.2 Plane Wave Reflection and Transmission	209	(4)
5.10.3 Spherical Wave Reflection at a Plane Interface	213	(3)
5.10.4 Effects of Turbulence	216	(1)
5.11 SOUND PROPAGATION OUTDOORS, GENERAL CONCEPTS	217	(28)
5.11.1 Methodology	217	(1)
5.11.2 Limits to Accuracy of Prediction	218	(1)
5.11.3 Outdoor Sound Propagation Prediction Schemes	219	(1)
5.11.4 Geometrical Spreading	220	(1)
5.11.5 Directivity Index	221	(1)
5.11.6 Excess Attenuation Factor	221	(4)
5.11.7 Air Absorption	225	(1)
5.11.8 Shielding by Barriers, Houses and Process Equipment/Industrial Buildings	225	(2)
5.11.9 Attenuation Due to Forests and Dense Foliage	227	(1)
5.11.10 Ground Effects	228	(5)
5.11.10.1 CONCAWE Method	229	(1)
5.11.10.2 Simple Method (Hard or Soft Ground)	230	(1)
5.11.10.3 Plane Wave Method	230	(1)
5.11.10.4 ISO 9613-2 (1996) Method	230	(2)
5.11.10.5 Detailed, Accurate and Complex Method	232	(1)
5.11.11 Image Inversion and Increased Attenuation at Large Distance	233	(1)
5.11.12 Meteorological Effects	234	(10)
5.11.12.1 Attenuation in the Shadow Zone (Negative Sonic Gradient)	237	(1)
5.11.12.2 Excess Attenuation Calculated According to Tonin (1985)	238	(1)
5.11.12.3 Excess Attenuation Calculated According to CONCAWE	239	(5)
5.11.12.4 Excess Attenuation Calculated According to ISO 9613-2 (1996)	244	(1)
5.11.13 Combined Excess Attenuation Model	244	(1)
CHAPTER SIX Sound power, its use and measurement	245	(28)
6.1 INTRODUCTION	245	(1)
6.2 RADIATION IMPEDANCE	246	(2)
6.3 RELATION BETWEEN SOUND POWER AND SOUND PRESSURE	248	(1)
6.4 RADIATION FIELD OF A SOUND SOURCE	249	(3)
6.4.1 Free-field Simulation in an Anechoic Room	250	(2)
6.4.2 Sound Field Produced in an Enclosure	252	(1)
6.5 DETERMINATION OF SOUND POWER USING INTENSITY MEASUREMENTS	252	(1)
6.6 DETERMINATION OF SOUND POWER USING CONVENTIONAL PRESSURE MEASUREMENTS	253	(16)
6.6.1 Measurement in Free or Semi-free Field	254	(4)
6.6.2 Measurement in a Diffuse Field	258	(3)
6.6.2.1 Substitution Method	260	(1)
6.6.2.2 Absolute Method	260	(1)
6.6.3 Field Measurement	261	(10)
6.6.3.1 Semi-reverberant Field Measurements by Method One	261	(2)
6.6.3.2 Semi-reverberant Field Measurements by Method Two	263	(1)
6.6.3.3 Semi-reverberant Field Measurements by Method Three	263	(2)
6.6.3.4 Near-field Measurements	265	(4)
6.7 DETERMINATION OF SOUND POWER USING SURFACE VIBRATION MEASUREMENTS	269	(2)
6.8 SOME USES OF SOUND POWER INFORMATION	271	(2)
6.8.1 The Far Free Field	271	(1)
6.8.2 The Near Free Field	272	(1)
CHAPTER SEVEN Sound in enclosed spaces	273	(62)
7.1 INTRODUCTION	273	(3)
7.1.1 Wall-Interior Modal Coupling	274	(1)
7.1.2 Sabine Rooms	274	(1)
7.1.3 Flat and Long Rooms	275	(1)
7.2 LOW FREQUENCIES	276	(5)
7.3 BOUND BETWEEN LOW-FREQUENCY AND HIGH-FREQUENCY BEHAVIOUR	281	(3)
7.3.1 Modal Density	282	(1)
7.3.2 Modal Damping and Bandwidth	282	(1)
7.3.3 Modal Overlap	283	(1)
7.3.4 Cross-over Frequency	284	(1)
7.4 HIGH FREQUENCIES, STATISTICAL ANALYSIS	284	(5)
7.4.1 Effective Intensity in a Diffuse Field	285	(2)
7.4.2 Energy Absorption at Boundaries	287	(1)
7.4.3 Air Absorption	287	(1)
7.4.4 Steady-state Response	288	(1)
7.5 TRANSIENT RESPONSE	289	(8)
7.5.1 Classical Description	290	(1)
7.5.2 Modal Description	291	(3)
7.5.3 Empirical Description	294	(2)
7.5.4 Mean Free Path	296	(1)
7.6 MEASUREMENT OF THE ROOM CONSTANT	297	(2)
7.6.1 Reference Sound Source Method	297	(1)
7.6.2 Reverberation Time Method	298	(1)
7.7 POROUS SOUND ABSORBERS	299	(7)
7.7.1 Measurement of Absorption Coefficients	299	(4)
7.7.2 Noise Reduction Index (NRI)	303	(1)
7.7.3 Porous Liners	303	(1)
7.7.4 Porous Liners with Perforated Panel Facings	304	(1)
7.7.5 Sound Absorption Coefficients of Materials in Combination	305	(1)
7.8 PANEL SOUND ABSORBERS	306	(4)
7.8.1 Empirical Method	306	(2)
7.8.2 Analytical Method	308	(2)
7.9 FLAT AND LONG ROOMS	310	(17)
7.9.1 Flat Room with Specularly Reflecting Floor and Ceiling	312	(2)
7.9.2 Flat Room with Diffusely Reflecting Floor and Ceiling	314	(6)
7.9.3 Flat Room with Specularly and Diffusely Reflecting Boundaries	320	(2)
7.9.4 Long Room with Specularly Reflecting Walls	322	(2)
7.9.5 Long Room with Circular Cross-section and Diffusely Reflecting wall	324	(2)
7.9.6 Long Room with Rectangular Cross-Section	326	(1)
7.10 APPLICATIONS OF SOUND ABSORPTION	327	(1)
7.10.1 Relative Importance of the Reverberant Field	327	(1)
7.10.2 Reverberation Control	327	(1)
7.11 AUDITORIUM DESIGN	328	(7)
7.11.1 Reverberation Time	328	(2)
7.11.2 Early Decay Time (EDT)	330	(1)
7.11.3 Clarity(C80)	331	(1)
7.11.4 Envelopment	331	(1)
7.11.5 Interaural Cross Correlation Coefficient, JACC	331	(1)
7.11.6 Background Noise Level	332	(1)
7.11.7 Total Sound Level or Loudness, G	332	(1)
7.11.8 Diffusion	332	(1)
7.11.9 Speech Intelligibility	333	(1)
7.11.10 Estimation of Parameters for Occupied Concert Halls	333	(1)
7.11.11 Optimum Volumes for Auditoria	334	(1)
CHAPTER EIGHT Partitions, enclosures and barriers	335	(71)
8.1 INTRODUCTION	335	(1)
8.2 SOUND TRANSMISSION THROUGH PARTITIONS	336	(30)
8.2.1 Bending Waves	336	(5)
8.2.2 Transmission Loss	341	(4)
8.2.3 Impact Isolation	345	(2)
8.2.4 Panel Transmission Loss (or Sound Reduction Index)	347	(9)
8.2.5 Sandwich Panels	356	(1)
8.2.6 Double Wall Transmission Loss	356	(9)
8.2.6.1 Staggered Studs	364	(1)
8.2.6.2 Panel Damping	365	(1)
8.2.7 Triple Wall Sound Transmission Loss	365	(1)
8.2.8 Common Building Materials	366	(1)
8.2.9 Sound-absorptive Linings	366	(1)
8.3 COMPOSITE TRANSMISSION LOSS	366	(9)
8.4 ENCLOSURES	375	(12)
8.4.1 Noise Inside Enclosures	375	(1)
8.4.2 Noise Outside Enclosures	375	(3)
8.4.3 Personnel Enclosures	378	(3)
8.4.4 Enclosure Windows	381	(1)
8.4.5 Enclosure Leakages	382	(1)
8.4.6 Access and Ventilation	383	(1)
8.4.7 Enclosure Vibration Isolation	384	(1)
8.4.8 Enclosure Resonances	384	(2)
8.4.9 Close-fitting Enclosures	386	(1)
8.4.10 Partial Enclosures	386	(1)
8.5 BARRIERS	387	(16)
8.5.1 Diffraction at the Edge of a Thin Sheet	388	(3)
8.5.2 Outdoor Barriers	391	(11)
8.5.2.1 Thick Barriers	394	(4)
8.5.2.2 Shielding by Terrain	398	(1)
8.5.2.3 Effects of Wind and Temperature Gradients on Barrier Attenuation	398	(2)
8.5.2.4 ISO 9613-2 Approach to Barrier Insertion Loss Calculations	400	(2)
8.5.3 Indoor Barriers	402	(1)
8.6 PIPE LAGGING	403	(3)
8.6.1 Porous Material Lagging	403	(1)
8.6.2 Impermeable Jacket and Porous Blanket Lagging	404	(2)
CHAPTER NINE Muffling devices	406	(67)
9.1 INTRODUCTION	406	(1)
9.2 MEASURES OF PERFORMANCE	406	(1)
9.3 DIFFUSERS AS MUFFLING DEVICES	407	(1)
9.4 CLASSIFICATION OF MUFFLING DEVICES	408	(1)
9.5 ACOUSTIC IMPEDANCE	409	(2)
9.6 LUMPED ELEMENT DEVICES	411	(9)
9.6.1 Impedance of an Orifice or a Short Narrow Duct	411	(8)
9.6.1.1 End Correction	414	(3)
9.6.1.2 Acoustic Resistance	417	(2)
9.6.2 Impedance of a Volume	419	(1)
9.7 REACTIVE DEVICES	420	(24)
9.7.1 Acoustical Analogs of Kirchhoffs Laws	420	(1)
9.7.2 Side Branch Resonator	421	(4)
9.7.3 Resonator Mufflers	425	(2)
9.7.4 Expansion Chamber	427	(4)
9.7.5 Small Engine Exhaust	431	(2)
9.7.6 Lowpass Filter	433	(5)
9.7.7 Pressure Drop Calculations for Reactive Muffling Devices	438	(4)
9.7.8 Flow-generated Noise	442	(2)
9.8 LINED DUCTS	444	(18)
9.8.1 Locally Reacting and Bulk Reacting Liners	445	(1)
9.8.2 Liner Specification	446	(2)
9.8.3 Lined Duct Silencers	448	(12)
9.8.3.1 Flow Effects	455	(1)
9.8.3.2 Higher Order Mode Propagation	456	(4)
9.8.4 Cross-sectional Discontinuities	460	(2)
9.8.5 Pressure Drop Calculations for Dissipative Mufflers	462	(1)
9.9 DUCT BENDS	462	(1)
9.10 UNLINED DUCTS	463	(1)
9.11 EFFECT OF DUCT END REFLECTIONS	463	(1)
9.12 DUCT BREAK-OUT NOISE	463	(3)
9.12.1 Break-out Sound Transmission	463	(3)
9.12.2 Break-in Sound Transmission	466	(1)
9.13 LINED PLENUM ATTENUATOR	466	(2)
9.14 WATER INJECTION	468	(1)
9.15 DIRECTIVITY OF EXHAUST DUCTS	469	(4)
CHAPTER TEN Vibration control	473	(37)
10.1 INTRODUCTION	473	(2)
10.2 VIBRATION ISOLATION	475	(15)
10.2.1 Single-degree-of-freedom Systems	476	(6)
10.2.2 Four-isolator Systems	482	(2)
10.2.3 Two-stage Vibration Isolation	484	(2)
10.2.4 Practical Isolator Considerations	486	(4)
10.2.4.1 Lack of Stiffness of Equipment Mounted on Isolators	488	(1)
10.2.4.2 Lack of Stiffness of Foundations	488	(2)
10.2.4.3 Superimposed Loads on Isolators	490	(1)
10.3 TYPES OF ISOLATORS	490	(4)
10.3.1 Rubber	490	(1)
10.3.2 Metal Springs	491	(2)
10.3.3 Cork	493	(1)
10.3.4 Felt	493	(1)
10.3.5 Air Springs	493	(1)
10.4 VIBRATION ABSORBERS	494	(3)
10.5 VIBRATION MEASUREMENT	497	(7)
10.5.1 Acceleration Transducers	497	(5)
10.5.1.1 Sources of Measurement Error	500	(1)
10.5.1.2 Sources of Error in the Measurement of Transients	500	(1)
10.5.1.3 Accelerometer Calibration	501	(1)
10.5.1.4 Accelerometer Mounting	501	(1)
10.5.1.5 Piezo-resistive Accelerometers	502	(1)
10.5.2 Velocity Transducers	502	(1)
10.5.3 Instrumentation Systems	503	(1)
10.5.4 Units of Vibration	504	(1)
10.6 DAMPING OF VIBRATING SURFACES	504	(3)
10.6.1 When Damping is Effective and Ineffective	504	(2)
10.6.2 Damping Methods	506	(1)
10.7 MEASUREMENT OF DAMPING	507	(3)
CHAPTER ELEVEN Sound power and sound pressure level estimation procedures	510	(60)
11.1 INTRODUCTION	510	(1)
11.2 FAN NOISE	511	(4)
11.3 AIR COMPRESSORS	515	(4)
11.3.1 Small Compressors	515	(1)
11.3.2 Large Compressors (Noise Levels Within the Inlet and Exit Piping)	516	(2)
11.3.2.1 Centrifugal Compressors (Interior Noise Levels)	516	(1)
11.3.2.2 Rotary or Axial Compressors (Interior Noise Levels)	516	(2)
11.3.2.3 Reciprocating compressors (interior noise)	518	(1)
11.3.3 Large Compressors (Exterior Noise Levels)	518	(1)
11.4 COMPRESSORS FOR REFRIGERATION UNITS	519	(1)
11.5 COOLING TOWERS	519	(4)
11.6 PUMPS	523	(1)
11.7 JETS	524	(5)
11.7.1 General Estimation Procedures	524	(4)
11.7.2 Gas and Steam Vents	528	(1)
11.7.3 General Jet Noise Control	528	(1)
11.8 CONTROL VALVES	529	(16)
11.8.1 Internal Sound Power Generation	530	(6)
11.8.2 Internal Sound Pressure Level	536	(3)
11.8.3 External Sound Pressure Level	539	(4)
11.8.4 High Exit Velocities	543	(1)
11.8.5 Control Valve Noise Reduction	543	(1)
11.8.6 Control Valves for Liquids	543	(2)
11.8.7 Control Valves for Steam	545	(1)
11.9 PIPE FLOW	545	(1)
11.10 BOILERS	546	(1)
11.11 TURBINES	547	(1)
11.12 DIESEL AND GAS-DRIVEN ENGINES	548	(3)
11.12.1 Exhaust Noise	549	(1)
11.12.2 Casing Noise	549	(2)
11.12.3 Inlet Noise	551	(1)
11.13 FURNACE NOISE	551	(2)
11.14 ELECTRIC MOTORS	553	(1)
11.14.1 Small Electric Motors (Below 300 kW)	553	(1)
11.14.2 Large Electric Motors (Above 300 kW)	554	(1)
11.15 GENERATORS	554	(1)
11.16 TRANSFORMERS	554	(2)
11.17 GEARS	556	(1)
11.18 TRANSPORTATION NOISE	557	(13)
11.18.1 Road Traffic Noise	557	(6)
11.18.1.1 UK DoT model (CoRTN)	557	(4)
11.18.1.2 United States FWHA Traffic Noise Model (TNM)	561	(1)
11.18.1.3 Other Models	562	(1)
11.18.2 Rail Traffic Noise	563	(5)
11.18.3 Aircraft Noise	568	(2)
CHAPTER TWELVE Active noise control	570	(26)
12.1 INTRODUCTION	570	(3)
12.2 ACTIVE CONTROL OF SOUND PROPAGATION IN DUCTS	573	(9)
12.2.1 Active Control of Plane Wave Propagation	573	(1)
12.2.2 Active Control of Higher Order Mode Propagation	573	(1)
12.2.3 Periodic Feedforward Controller	574	(2)
12.2.4 Random Noise Feedforward Controller	576	(3)
12.2.5 Feedback Controller	579	(1)
12.2.6 Control Sound Sources	580	(2)
12.2.7 Microphones	582	(1)
12.3 ACTIVE CONTROL OF SOUND RADIATION FROM VIBRATING STRUCTURES	582	(4)
12.3.1 Physical Control Mechanisms	583	(2)
12.3.2 Control Actuators and Error Sensors	585	(1)
12.4 SOUND TRANSMISSION INTO ENCLOSED SPACES	586	(5)
12.5 ACTIVE VIBRATION ISOLATION	591	(1)
12.6 ELECTRONIC CONTROLLER DESIGN	592	(4)
CHAPTER THIRTEEN Survey of analytical techniques for the estimation of sound power levels	596	(6)
13.1 INTRODUCTION	596	(1)
13.2 LOW-FREQUENCY REGION	597	(3)
13.2.1 Helmholtz Method	598	(1)
13.2.2 Rayleigh Method	599	(1)
13.2.3 Simple Acoustic Modelling	600	(1)
13.3 HIGH-FREQUENCY REGION	600	(2)
APPENDIX A Wave equation derivation	602	(7)
A.1 CONSERVATION OF MASS	602	(1)
A.2 EULER'S EQUATION	603	(1)
A.3 EQUATION OF STATE	604	(1)
A.4 WAVE EQUATION (LINEARIZED)	605	(4)
APPENDIX B Properties of materials	609	(2)
APPENDIX C Acoustical properties of porous materials	611	(17)
C.1 FLOW RESISTANCE AND RESISTIVITY	611	(2)
C.2 SOUND PROPAGATION IN POROUS MEDIA	613	(2)
C.3 SOUND REDUCTION DUE TO PROPAGATION THROUGH A POROUS MATERIAL	615	(1)
C.4 MEASUREMENT AND CALCULATION OF ABSORPTION COEFFICIENTS	616	(12)
C.4.1 Porous Materials with a Backing Cavity	624	(1)
C.4.2 Porous Liner Covered with a Limp Impervious Layer	625	(1)
C.4.3 Porous Liner Covered with a Perforated Sheet	626	(1)
C.4.4 Porous Liner Covered with a Limp Impervious Layer and a Perforated Sheet	626	(2)
APPENDIX D Frequency analysis	628	(17)
D.1 DIGITAL FILTERING	628	(1)
D.2 DIGITAL FOURIER ANALYSIS	629	(12)
D.2.1 Power Spectrum	634	(3)
D.2.2 Sampling Frequency and Aliasing	637	(2)
D.2.3 Uncertainty Principle	639	(1)
D.2.4 Real-time Frequency	639	(1)
D.2.5 Weighting Functions	639	(2)
D.2.6 Zoom Analysis	641	(1)
D.3 IMPORTANT FUNCTIONS	641	(4)
D.3.1 Cross-spectrum	642	(1)
D.3.2 Coherence	643	(1)
D.3.3 Frequency Response (or Transfer) Function	643	(2)
References	645	(17)
List of acoustical standards	662	(20)
Glossary of symbols	682	(27)
Index	709