Industrial Noise Control and Acoustics (Dekker Mechanical Engineering)

535 Pages·2002·3.46 MB·English

by  Randall F. Barron

Industrial
Noise Control
and Acoustics
Randall F. Barron
Louisiana Tech University
Ruston, Louisiana, U.S.A.
Marcel Dekker, Inc. New York Basel
•
Copyright ©2001 by Marcel Dekker,Inc. All Rights Reserved.
Copyright © 2003 Marcel Dekker, Inc.
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Preface
Since the Walsh-Healy Act of 1969 was amended to include restrictions on
thenoiseexposureofworkers,therehasbeenmuchinterestandmotivation
in industry to reduce noise emitted by machinery. In addition to concerns
aboutairandwaterpollutionbycontaminants,effortshavealsobeendirec-
ted toward control of environmental noise pollution.
Inresponse tothese stimuli, facultyatmanyengineering schoolshave
developed and introduced courses in noise control, usually at the senior
design level. It is generally much more effective to design ‘‘quietness’’ into
aproductthantotryto‘‘fix’’thenoiseprobleminthefieldaftertheproduct
has been put on the market. Because of this, many engineering designs in
industry take into account the noise levels generated by a system.
Industrial Noise Control and Acoustics was developed as a result of
my 30 years of experience teaching senior-level undergraduate mechanical
engineering courses in noise control, directing graduate student research
projects, teaching continuing education courses on industrial noise control
to practicing engineers, and consulting on various industrial projects in
noise assessment and abatement. The book reflects this background,
including problems for engineering students to gain experience in applying
the principles presented in the text, and examples for practicing engineers
to illustrate the material. Several engineering case studies are included to
illustrate practical solutions of noise problems in industry. This book is
Copyright © 2003 Marcel Dekker, Inc.
designed to integrate the theory of acoustics with the practice of noise
control engineering.
Iwouldliketoexpressmymostsincereappreciationtothosestudents
in my classes who asked questions and made suggestions that helped make
the text more clear and understandable. My most heartfelt thanks are
reserved for my wife, Shirley, for her support and encouragement during
the months of book preparation, and especially during the years before I
even considered writing this book.
Randall F. Barron
Copyright © 2003 Marcel Dekker, Inc.
Contents
Prefaceiii
1Introduction1
1.1NoiseControl1
1.2HistoricalBackground3
1.3PrinciplesofNoiseControl7
1.3.1NoiseControlattheSource8
1.3.2NoiseControlintheTransmissionPath9
1.3.3NoiseControlattheReceiver9
References10
2BasicsofAcoustics12
2.1SpeedofSound12
2.2Wavelength,Frequency,andWaveNumber13
2.3AcousticPressureandParticleVelocity15
2.4AcousticIntensityandAcousticEnergyDensity17
2.5SphericalWaves21
2.6DirectivityFactorandDirectivityIndex24
2.7LevelsandtheDecibel27
2.8CombinationofSoundSources31
v
Copyright © 2003 Marcel Dekker, Inc.
2.9OctaveBands33
2.10WeightedSoundLevels34
Problems37
References40
3AcousticMeasurements41
3.1SoundLevelMeters42
3.2IntensityLevelMeters46
3.3OctaveBandFilters49
3.4AcousticAnalyzers50
3.5Dosimeter50
3.6MeasurementofSoundPower51
3.6.1SoundPowerMeasurementinaReverberant
Room52
3.6.2SoundPowerMeasurementinanAnechoicor
Semi-AnechoicRoom58
3.6.3SoundPowerSurveyMeasurements62
3.6.4MeasurementoftheDirectivityFactor66
3.7NoiseMeasurementProcedures69
Problems73
References76
4TransmissionofSound78
4.1TheWaveEquation78
4.2ComplexNumberNotation83
4.3WaveEquationSolution84
4.4SolutionforSphericalWaves88
4.5ChangesinMediawithNormalIncidence91
4.6ChangesinMediawithObliqueIncidence96
4.7SoundTransmissionThroughaWall101
4.8TransmissionLossforWalls107
4.8.1RegionI:Stiffness-ControlledRegion108
4.8.2ResonantFrequency111
4.8.3RegionII:Mass-ControlledRegion112
4.8.4CriticalFrequency113
4.8.5RegionIII:Damping-ControlledRegion113
4.9ApproximateMethodforEstimatingtheTL117
4.10TransmissionLossforCompositeWalls120
4.10.1ElementsinParallel121
4.10.2CompositeWallwithAirSpace122
4.10.3Two-LayerLaminate127
4.10.4Rib-StiffenedPanels131
Copyright © 2003 Marcel Dekker, Inc.
4.11SoundTransmissionClass134
4.12AbsorptionofSound139
4.13AttenuationCoefficient143
Problems153
References160
5NoiseSources162
5.1SoundTransmissionIndoorsandOutdoors162
5.2FanNoise164
5.3ElectricMotorNoise169
5.4PumpNoise171
5.5GasCompressorNoise173
5.6TransformerNoise177
5.7CoolingTowerNoise178
5.8NoisefromGasVents182
5.9ApplianceandEquipmentNoise185
5.10ValveNoise186
5.10.1SourcesofValveNoise186
5.10.2NoisePredictionforGasFlows188
5.10.3NoisePredictionforLiquidFlows190
5.11AirDistributionSystemNoise192
5.11.1NoiseAttenuationinAirDistribution
Systems193
5.11.2NoiseGenerationinAirDistributionSystem
Fittings195
5.11.3NoiseGenerationinGrilles198
5.12TrafficNoise207
5.13TrainNoise211
5.13.1RailroadCarNoise211
5.13.2LocomotiveNoise213
5.13.3CompleteTrainNoise214
Problems217
References222
6AcousticCriteria225
6.1TheHumanEar226
6.2HearingLoss229
6.3IndustrialNoiseCriteria231
6.4SpeechInterferenceLevel235
6.5NoiseCriteriaforInteriorSpaces238
6.6CommunityReactiontoEnvironmentalNoise243
6.7TheDay-NightLevel247
Copyright © 2003 Marcel Dekker, Inc.
6.7.1EPACriteria247
6.7.2EstimationofCommunityReaction250
6.8HUDCriteria253
6.9AircraftNoiseCriteria255
6.9.1PerceivedNoiseLevel256
6.9.2NoiseExposureForecast257
Problems262
References267
7RoomAcoustics269
7.1SurfaceAbsorptionCoefficients269
7.1.1ValuesforSurfaceAbsorptionCoefficients269
7.1.2NoiseReductionCoefficient270
7.1.3MechanismofAcousticAbsorption271
7.1.4AverageAbsorptionCoefficient274
7.2Steady-StateSoundLevelinaRoom274
7.3ReverberationTime281
7.4EffectofEnergyAbsorptionintheAir289
7.4.1Steady-StateSoundLevelwithAbsorptionin
theAir289
7.4.2ReverberationTimewithAbsorptioninthe
Air291
7.5NoisefromanAdjacentRoom293
7.5.1SoundSourceCoveringOneWall293
7.5.2SoundTransmissionfromanAdjacentRoom295
7.6AcousticEnclosures299
7.6.1SmallAcousticEnclosures300
7.6.2LargeAcousticEnclosures304
7.6.3DesignPracticeforEnclosures311
7.7AcousticBarriers312
7.7.1BarriersLocatedOutdoors313
7.7.2BarriersLocatedIndoors317
Problems321
References328
8SilencerDesign330
8.1SilencerDesignRequirements330
8.2LumpedParameterAnalysis332
8.2.1AcousticMass332
8.2.2AcousticCompliance335
8.2.3AcousticResistance338
8.2.4TransferMatrix339
Copyright © 2003 Marcel Dekker, Inc.
8.3TheHelmholtzResonator341
8.3.1HelmholtzResonatorSystem341
8.3.2ResonancefortheHelmholtzResonator342
8.3.3AcousticImpedancefortheHelmholtz
Resonator343
8.3.4Half-PowerBandwidth344
8.3.5SoundPressureLevelGain348
8.4SideBranchMufflers350
8.4.1TransmissionLossforaSide-BranchMuffler351
8.4.2DirectedDesignProcedureforSide-Branch
Mufflers357
8.4.3ClosedTubeasaSide-BranchMuffler361
8.4.4OpenTube(Orifice)asaSideBranch365
8.5ExpansionChamberMufflers368
8.5.1TransmissionLossforanExpansionChamber
Muffler368
8.5.2DesignProcedureforSingle-Expansion
ChamberMufflers371
8.5.3Double-ChamberMufflers373
8.6DissipativeMufflers377
8.7EvaluationoftheAttenuationCoefficient381
8.7.1EstimationoftheAttenuationCoefficient381
8.7.2EffectiveDensity383
8.7.3EffectiveElasticityCoefficient384
8.7.4EffectiveSpecificFlowResistance385
8.7.5CorrectionforRandomIncidenceEndEffects387
8.8CommercialSilencers389
8.9PlenumChambers391
Problems397
References405
9VibrationIsolationforNoiseControl406
9.1UndampedSingle-Degree-of-Freedom(SDOF)System407
9.2DampedSingle-Degree-of-Freedom(SDOF)System410
9.2.1CriticallyDampedSystem411
9.2.2Over-DampedSystem412
9.2.3Under-DampedSystem412
9.3DampingFactors413
9.4ForcedVibration419
9.5MechanicalImpedanceandMobility424
9.6Transmissibility427
9.7RotatingUnbalance431
Copyright © 2003 Marcel Dekker, Inc.