Project Studio Acoustics

ProjectProject StudioStudio AcousticsAcoustics

SolutionsSolutions forfor betterbetter soundingsounding roomsrooms

HousekeepingHousekeeping

•• PleasePlease turnturn offoff cellcell phonesphones •• WeWe havehave lotslots toto cover!cover! •• PleasePlease keepkeep questionsquestions onon tracktrack

1 IntroductionIntroduction

•• WeWe WILLWILL talktalk aboutabout thethe acousticsacoustics ofof projectproject studiosstudios •• WeWe willwill NOTNOT talktalk aboutabout concertconcert hall or churchchurch acousticsacoustics •• ShortenedShortened versionversion ofof AESAES T3T3 andand T5T5 TutorialsTutorials •• 4:14:1 compressioncompression !!!!

ProjectProject StudioStudio StatisticsStatistics

• 350,000 project studios worldwide • 93% of A titles go through project studio at some phase of production • In homes, in studios, in post- production facilities • Translation to the outside world at issue!

2 22 TypesTypes ofof roomsrooms

• Sound Production – Acoustics of room contribute to the character of the recorded sound • Sound Reproduction – Acoustics of room provide a neutral environment to audition pre-recorded sound – Let’s talk about this

IntroductionIntroduction

•• WhyWhy talktalk aboutabout acoustics?acoustics? •• AcousticsAcoustics areare audible!audible! •• ContributeContribute toto overover 50%50% ofof qualityquality •• AcousticsAcoustics areare fixablefixable

3 What’sWhat’s Acoustics?Acoustics?

• It’s about the speaker/room/listener interface • It’s what separates “Major” studios from “Project” studios • It’s today’s key issue!

TheThe AcousticAcoustic InterfaceInterface

Source Power Amplifiers

Console Equalizers

•• ElectronicsElectronics InterfaceInterface isis underunder controlcontrol • Take control of the acoustic interface

4 WarningWarning !!

RoomRoom acousticsacoustics willwill messmess youyou upup !!

AcousticalAcoustical IssuesIssues

1.1. RoomRoom reflectionsreflections 2.2. RoomRoom echoesechoes 3.3. ReverberationReverberation timetime 5.5. StandingStanding waveswaves 6.6. RattlesRattles 7.7. BackgroundBackground noisenoise 8.8. SoundSound IsolationIsolation

5 AcousticAcoustic

TheThe DesignDesign ProcessProcess

1.1.Dimension Dimension thethe roomroom 7.7.Determine Determine 2.2.Sound Sound isolationisolation diffusiondiffusion areaarea 8. Determine 3.3.Noise Noise controlcontrol 8. Determine treatmenttreatment 4.4.Vibration Vibration controlcontrol locationslocations 5.5.Model Model decaydecay timetime 9.9.Treat Treat echoesechoes 6.6.Determine Determine absorptionabsorption 10.10.Place Place listenerlistener areaarea 11.11.Place Place soundsound systemsystem 12.12.Tune Tune itit allall

6 ……But But FirstFirst aa BitBit ofof TheoryTheory

•• SoundSound isis –– VibratingVibrating airair –– ChangingChanging pressurepressure –– PerceivedPerceived by our earear-brain-brain –– FrequencyFrequency of pressure changeschanges determinesdetermines pitchpitch

AcousticAcoustic WavelengthWavelength

Sound Propagates at 1.13ft/msec A 1 kHz Signal +

Air 0 Ft. Pressure 1.13 2.26 -

+ A 500 Hz Signal

7 RoomRoom DimensioningDimensioning

StandingStanding WavesWaves

RoomRoom DimensioningDimensioning

•• HowHow muchmuch roomroom dodo youyou have?have? –– II cantcant helphelp you!you! •• StandingStanding waveswaves –– II cancan help!help!

8 StandingStanding WavesWaves a.k.a.a.k.a. RoomRoom ModesModes

•• StandingStanding waveswaves happen Loudspeaker whenwhen roomroom dimensiondimension isis equalequal toto soundsound wavelengthwavelength •• AlsoAlso atat 0.5,0.5, 1.5,1.5, 2,2, 2.5,2.5, Listener 3,3, etc.etc. timestimes wavelengthwavelength

StandingStanding WavesWaves

•• StandingStanding waveswaves causecause –– ResonancesResonances –– UnevenUneven frequencyfrequency response –– PoorPoor bassbass impactimpact –– DifferentDifferent bassbass atat eacheach seatseat –– CommonCommon problems are in the 30 Hz to 150150 HzHz rangerange

9 AA ResonantResonant frequencyfrequency

•• NoNo wall;wall; nono reflectionreflection

AA ResonantResonant frequencyfrequency

•• AfterAfter reflection,reflection, signalsignal nullsnulls overlapoverlap

10 AA ResonantResonant frequencyfrequency

•• AfterAfter reflection,reflection, signalsignal nullsnulls overlapoverlap

AA NonNon-Resonant-Resonant frequencyfrequency

•• NoNo wall;wall; nono reflectionreflection

11 AA NonNon-Resonant-Resonant frequencyfrequency

•• NoNo nullnull overlapsoverlaps

StandingStanding WavesWaves

•• StandingStanding waveswaves areare aa productproduct ofof thethe roomroom dimensionsdimensions –– AllAll roomsrooms willwill havehave somesome standingstanding waveswaves

–– ResonanceResonance overlapsoverlaps areare thethe resultresult ofof thethe ratioratio ofof thethe roomroom dimensionsdimensions •• IntensityIntensity ofof roomroom modesmodes isis determineddetermined byby thethe wallwall densitydensity andand stiffnessstiffness

12 StandingStanding WavesWaves (continued)(continued)

•• StandingStanding wavewave modesmodes areare –– AxialAxial – The most important ones •• BetweenBetween twotwo oppositeopposite wallswalls –– TangentialTangential – Not importantimportant •• BetweenBetween twotwo pairspairs ofof wallswalls –– ObliqueOblique – Not importantimportant •• BetweenBetween allall roomroom surfacessurfaces

StandingStanding WavesWaves AA SecondSecond HarmonicHarmonic LengthLength AxialAxial StandingStanding WaveWave

SUB

Low Relative Pressure Low Relative Pressure

13 StandingStanding WavesWaves PressurePressure RepresentationRepresentation forfor 11stst,, 22ndnd,, 33rdrd,, 44thth HarmonicsHarmonics

1st Harmonic 2nd Harmonic

11 11 33 22 44 44 3rd Harmonic 4th Harmonic

11 11 55 11 33 55 77 66 22 66 88 88 88 88

StandingStanding WavesWaves PressurePressure PolarityPolarity

1st Harmonic

•• TheThe acousticacoustic polaritypolarity changeschanges + _ aroundaround thethe nullnull

1/2

14 StandingStanding WavesWaves PressurePressure PolaritiesPolarities

1st Harmonic 2nd Harmonic

_ _ + ++

1/2 1/4 3/4

3rd Harmonic 4th Harmonic

_ _ _ _ + + + + +

1/6 1/2 5/6 1/8 3/8 5/8 7/8

StandingStanding WavesWaves ModalModal decaydecay

•• ExampleExample ofof roomroom modalmodal decaydecay plotplot •• LongLong decaydecay •• MostMost audible effecteffect ofof roomroom modesmodes

15 WaysWays toto DealDeal WithWith StandingStanding WavesWaves ((RoomRoom ModesModes CanCan NeverNever BeBe Eliminated)Eliminated)

•• ChangeChange oneone oror moremore dimensionsdimensions –– MinimizesMinimizes resonanceresonance pilepile-ups-ups

–– AimAim forfor eveneven modalmodal distributiondistribution (>5%(>5% difference)difference) •• MoveMove subwoofersubwoofer locationlocation –– DriveDrive modemode outout-of-phase-of-phase to reduce relative amplitudeamplitude •• UseUse bassbass absorptionabsorption oror absorptiveabsorptive wallswalls •• MoveMove seatingseating locationlocation –– MovesMoves thethe listenerlistener outout ofof peakspeaks andand dipsdips •• EqualizeEqualize

StandingStanding WavesWaves ResonanceResonance FrequenciesFrequencies

Equation:

F = n1130/2D (in ft) F = n345/2D (in m)

Where F is frequency n is the harmonic D is the distance between walls

16 SolutionsSolutions toto StandingStanding WavesWaves RoomRoom DimensionsDimensions

•• DetermineDetermine roomroom dimensionsdimensions •• DetermineDetermine modesmodes (F=n1130/2d)(F=n1130/2d) •• FindFind modalmodal overlapsoverlaps •• LocateLocate dipsdips forfor 11stst,, 22ndnd,, 33rdrd,, 44thth harmonicsharmonics

SolutionsSolutions toto StandingStanding WavesWaves RoomRoom DimensionsDimensions (continued)(continued)

•• CalculationCalculation programsprograms –– RPGRPG RoomRoom OptimizerOptimizer –– CARACARA –– THXTHX RoomRoom ModeMode CalcCalc –– StereophileStereophile GuideGuide toto HomeHome TheatreTheatre –– PMIPMI modelingmodeling programprogram

17 Home Theater Go To ROOM MODES Performance Media Industries Diaphragm atic Absorber

ROOM DIMENSIONS (ft.) Modal Frequencies Length: 19.690 feet new 143.47 5 187.21 287.09 Width: 15.090 feet new 114.78 Height: 9.840 feet new 4 149.77 229.67 86.08 Speed Of Sound in ft./sec 1130 3 112.33 172.26 AXIAL M ODAL FREQUENCIES OF EACH DIM ENSION 57.39 2 74.88 114.84

Modal Har m onics Length Width Height 28.69 Harmonic 1 37.44 57.42 1 28.69 37.44 57.42 0 2 57.39 74.88 114.84 0.00 50.00 100.00 150.00 200.00 250.00 300.00 350.00 3 86.08 112.33 172.26 Frequency (Hz) 4 114.78 149.77 229.67 5 143.47 187.21 287.09 Length Width He ight

Length Width Length He ight Width Length Width Length He ight Length Width Height Width He ight He ight 28.69 37.44 57.39 57.42 74.88 86.08 112.33 114.78 114.84 143.47 149.77 172.26 187.21 229.67 287.09 23.36% 34.76% 0.05% 23.32% 13.01% 23.36% 2.14% 0.05% 19.96% 4.20% 13.06% 7.99% 18.49% 20.00% Warning! Warning! Warning! Warning!

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260 270 280 290 300 310

SolutionsSolutions toto StandingStanding WavesWaves RoomRoom DimensionsDimensions

•• ForFor roomroom dimensionsdimensions that are “useable” this guidelineguideline isis handyhandy •• 1.1w/h1.1w/h ≤≤ l/hl/h ≤≤ 4.54.5 w/hw/h- -4 4 andand ww << 3h3h andand ll << 3h3h •• WhereWhere ll == length,length, ww == wiwidth,dth, andand hh == heightheight •• l,l, w,w, andand hh whichwhich areare wiwithinthin ±5%±5% ofof integerinteger valuesvalues shouldshould bebe avoidedavoided

Source:Source: RobertRobert Walker,Walker, BBC,BBC, “EBU“EBU TechnicalTechnical Bulletin”Bulletin” 32763276-E-E

18 SolutionsSolutions toto StandingStanding WavesWaves RoomRoom ShapesShapes

Loudspeaker •• ComplicatesComplicates AcousticAcoustic modelingmodeling andand computationscomputations •• Doesn’tDoesn’t getget ridrid ofof standingstanding waveswaves or reflectionsreflections • Not recommended Listener • Not recommended

SolutionsSolutions toto StandingStanding WavesWaves SubwooferSubwoofer andand SpeakerSpeaker PlacementPlacement

Loudspeaker •• DrivingDriving roomroom standingstanding waveswaves inin cancellationcancellation areasareas cancan improveimprove responseresponse

19 SolutionsSolutions toto StandingStanding WavesWaves PlacementPlacement ——1 1 SubwooferSubwoofer

•• HowHow toto improveimprove aa 2nd2nd orderorder standingstanding Original Modes wavewave –– TheThe subwoofersubwoofer drivesdrives thethe ++ andand -- areas equally, + – + areas equally, resultingresulting inin reductionreduction ofof resonanceresonance SubwooferSubwoofer Resulting Modes

SolutionsSolutions toto StandingStanding WavesWaves PlacementPlacement ——2 2 SubwoofersSubwoofers

•• ImprovingImproving aa 2nd2nd orderorder standingstanding wavewave Original Modes –– ConnectConnect thethe 22 subwooferssubwoofers togethertogether asas “in“in-phase”-phase” –– TheThe 22 subwooferssubwoofers drivedrive + – + thethe ++ andand --areas areas equally,equally, resultingresulting inin Subwoofer reductionreduction ofof resonanceresonance Output Subwoofer 1 SubwooferSubwoofer 22 Subwoofer 1 From –– Experiment a lot Controller Experiment a lot Resulting Modes

20 SubwooferSubwoofer PlacementPlacement ReducingReducing StandingStanding WavesWaves --A A goodgood solutionsolution

• 4 subwoofers • They can be small and hidden • It’s the latest research findings • Todd Welti et al.

SubwooferSubwoofer PlacementPlacement AnotherAnother goodgood solutionsolution

• 2 subwoofers • More SPL • More standing waves

21 SolutionsSolutions toto StandingStanding WavesWaves “Fuzz”“Fuzz” AbsorptionAbsorption atat StandingStanding WaveWave

Original Modes •• PlacePlace absorberabsorber panelpanel atat nullnull (high(high velocity,velocity, lowlow pressurepressure area)area) •• PVPV = nRT ! !

AbsorberAbsorber PanelPanel Resulting Modes

SolutionsSolutions toto StandingStanding WavesWaves DiaphragmaticDiaphragmatic AbsorptionAbsorption

•• AbsorberAbsorber unitsunits areare resonatingresonating materialmaterial tunedtuned toto problemproblem frequenciesfrequencies •• AbsorberAbsorber boxbox isis filledfilled withwith “fuzz”“fuzz” Diaphragm •• WorksWorks upup toto 150Hz150Hz •• DesignDesign ofof bassbass absorberabsorber isis complexcomplex ——Use Use anan acousticalacoustical consultantconsultant

22 SolutionsSolutions toto StandingStanding WavesWaves HelmholtzHelmholtzAbsorption Absorption

•• HelmholtzHelmholtzunits units areare tunedtuned toto problemproblem frequencyfrequency •• AbsorberAbsorber boxbox isis filledfilled withwith fuzzfuzz •• WorksWorks downdown toto 80Hz80Hz •• DesignDesign ofof HelmholtzHelmholtz absorberabsorber isis extremelyextremely complexcomplex

SolutionsSolutions toto StandingStanding WavesWaves TheThe SpringTrapSpringTrap

•• CombinationCombination PistonicPistonicresonator resonator andand HelmholtzHelmholtz absorberabsorber

•• FF00 determineddetermined byby MassMass ––Spring Spring ––Air Air •• ReliableReliable andand predictablepredictable

23 SolutionsSolutions toto StandingStanding WavesWaves TheThe SpringTrapSpringTrap

•• CombinationCombination PistonicPistonicresonator resonator andand HelmholtzHelmholtz absorberabsorber

•• FF00 determineddetermined byby MassMass ––Spring Spring ––Air Air

SolutionsSolutions toto StandingStanding WavesWaves TheThe SpringTrapSpringTrap

•• CombinationCombination PistonicPistonicresonator resonator andand HelmholtzHelmholtz absorberabsorber

•• FF00 determineddetermined byby MassMass ––Spring Spring ––Air Air

24 SolutionsSolutions toto StandingStanding WavesWaves TheThe SpringTrapSpringTrap

•• FrontFront panelpanel suspendedsuspended onon springssprings •• PortPort onon bottombottom ofof cabinetcabinet

SolutionsSolutions toto StandingStanding WavesWaves TheThe SpringTrapSpringTrap

•• MineralMineral woolwool insideinside cavitycavity toto widenwiden resonanceresonance

25 SolutionsSolutions toto StandingStanding WavesWaves TheThe SpringTrapSpringTrap

•• SecondSecond chamberchamber resonatingresonating portport onon bottombottom ofof cabinetcabinet •• PortPort extendsextends upup toto middlemiddle ofof cabinetcabinet •• OptimizedOptimized byby PAMPAM ((WhiseWhise / / HuonHuonLabs) Labs)

SolutionsSolutions toto StandingStanding WavesWaves TheThe SpringTrapSpringTrap

•• TwoTwo fundamentalfundamental equationsequations •• PortedPorted resonantresonant enclosure:enclosure: –– FF == (c/2pi)(A/L’V)(c/2pi)(A/L’V)1/21/2 •• SpringSpring loadedloaded panelpanel resonance:resonance: –– FF == (1/2pi(1/2pi )(k/m))(k/m)1/21/2 •• PaperPaper presentedpresented atat AESAES 114114thth Convention,Convention, Amsterdam,Amsterdam, MarchMarch 20032003 •• PatentPatent PendingPending

26 SolutionsSolutions toto StandingStanding WavesWaves ResilientResilient WallsWalls

•• ResilientResilient wallswalls don’tdon’t RSIC Hat-Channel DW reflectreflect bass well SB or Vinyl Sheet DW •• SoundSound energyenergy isis absorbedabsorbed byby thethe PACPAC Bass to wall RSICRSIC rubberrubber isolatorisolator •• AddAdd SoundboardSoundboard oror LoadedLoaded VinylVinyl toto spreadspread Bass thethe resonanceresonance frequencyfrequency from wall •• YouYou getget isolationisolation too!too! Wall with PAC RSCI-1 Isolators

SolutionsSolutions toto StandingStanding WavesWaves ResilientResilient WallsWalls PACPAC RSIC1RSIC1

27 SolutionsSolutions toto StandingStanding WavesWaves ResilientResilient WallsWalls PACPAC RSIC1RSIC1

.8 *L .68 *L.55 *L .45 *L .32 *L .2 *L SolutionsSolutions .8 *H .68 *H .55 *H toto StandingStanding .45 *H .32 *H WavesWaves .2 *H SeatingSeating 63 251 314 188 126 27 PlacementPlacement 54 81 108 135 71 35 106 141 176

.2 *W

.32 *W

.45 *W

.55 *W

.68 *W

.8 *W

28 SolutionsSolutions toto StandingStanding WavesWaves EqualizationEqualization

•• AnalysisAnalysis Loudspeaker shouldshould bebe 1/3 Octave Equalization spatiallyspatially andand temporallytemporally averagedaveraged Pink Noise Multiplexer Microphone 3 Generator •• UseUse GoldGold Microphone 2 LineLine DSP30DSP30

Microphone 4 Analyzer,Analyzer, oror

Microphone 1 equivalentequivalent

SoundSound IsolationIsolation

29 SoundSound IsolationIsolation ––2 2 processesprocesses

•• SoundSound leakageleakage –– IsolateIsolate doors,doors, windows,windows, andand plumbingplumbing –– Isolate,Isolate, sealseal andand caulkcaulk allall leakageleakage pathspaths •• MechanicalMechanical TransmissionTransmission –– SpecialSpecial wall structuresstructures –– FloatingFloating floorfloor –– FloatingFloating ceilingceiling

IsolateIsolate FlankingFlanking PathsPaths

FullFull FlankingFlanking OffsetOffset OffsetOffset andand IsolatedIsolated

30 IsolateIsolate FlankingFlanking PathsPaths

Office BAD

InIn-Line-Line DoorsDoors AllowAllow aa Hallway Path Sound DirectDirect PathPath forfor NoiseNoise

Studio

Offset Doors Reduce Hallway Sound Offset Doors Reduce Path SoundSound TransmissionTransmission

Bedroom GOOD

NoiseNoise TransmissionTransmission DetectionDetection

Listen! Detect! Fix It!

Weather Strip Pink Noise Bursts

AC Outlet Expand

31 IsolationIsolation SolutionsSolutions

WallWall ConstructionConstruction

TheThe MechanismMechanism ofof SoundSound TransmissionTransmission

SoundSound WavesWaves SomeSome EnergyEnergy FromFrom SourceSource ReflectedReflected

Wall

SomeSome EnergyEnergy AbsorbedAbsorbed

SomeSome EnergyEnergy TransmittedTransmitted

32 WallWall ConstructionConstruction ResonanceResonance

SoundSound transmissiontransmission Wall atat resonanceresonance frequencyfrequency

•• AllAll wallwall surfacessurfaces havehave aa resonantresonant frequencyfrequency wherewhere theythey transmittransmit lotslots ofof energyenergy

Sound Transmission ½”½” DrywallDrywall ExampleExample

WallWall ConstructionConstruction DampedDamped ResonanceResonance

Wall

LoadedLoaded VinylVinyl barrierbarrier oror SoundSound boardboard

Sound Transmission With Dampener

33 WallWall ConstructionConstruction ConstrainedConstrained LayerLayer DampingDamping

Wall ViscoVisco-Elastic-Elastic polymer

Sound Transmission With Visco Elastic

WallWall ConstructionConstruction SpreadSpread ResonanceResonance

•• UnequalUnequal thicknessthickness

5/8”5/8” DWDW 1/2”1/2” DWDW

5/8”5/8” 1/2”1/2” Sound Transmission

Frequency

34 IsolationIsolation StrategiesStrategies

•• MoreMore MassMass •• DampDamp resonanceresonance •• DecoupleDecouple •• LargerLarger airgapairgap

WallWall ConstructionConstruction DecouplingDecoupling

RC1 DW DW DW SB or SoundCor DW

Single Stud RC1 Resilient Channel Warning:This is hard to make work!

35 WallWall ConstructionConstruction DecouplingDecoupling (continued)(continued)

DW DW DW DW

Staggered Stud Double Wall

StudwallStudwall IsolationIsolation

dB SPL NoiseNoise TransmissionTransmission CoefficientsCoefficients Isolation 80 Double Stud, 5/8” 70 Double Drywall, double 3” insulation 60 Double Stud, 5/8” 50 Drywall, 3” and 6” insulation 40 Staggered Stud, 5/8” drywall 30 Double ½” drywall, 20 studs 16” OC ½” drywall on studs 10 16” on center 0 100 1000 10000

36 StaggeredStaggered StudStud ConstructionConstruction

OriginalOriginal 22 xx 44 Retrofit Top Plate Retrofit Top Plate AdditionalAdditional 22 xx 22 TopTop OriginalOriginal 22 xx 44 PlatePlate 1616 inin

AddedAdded 22 inin 22 xx 44 StudStud 1616 inin

AddedAdded 22 xx 44

AdditionalAdditional Original 2 x 4 Original 2 x 4 22 xx 22 SoleSole Sole Plate Sole Plate PlatePlate

SuspendedSuspended WallWall ConstructionConstruction PACPAC RSCIRSCI-1-1 “The“The littlelittle Miracle”Miracle”

RSIC Hat-Channel DW DW DW SB or Vinyl Sheet DW

Single Stud PAC RSCI-1 Isolators STC40 STC 56 ! !

37 WallWall ConstructionConstruction StaggeredStaggered SeamsSeams

5/8” Sheetrock

½” Sheetrock

½” USG RC-1 Resilient Channel

1” fiberglass insulation (6 lbs/sq ft)

IsolatingIsolating thethe ceilingceiling andand floorfloor

–– FloatingFloating floorfloor constructionconstruction Carpet + pad

3/4" T&G Plywood Existing concrete floor Isolation Pads

–– FloatingFloating ceilingceiling consconstructiontruction (PAC(PAC RSCIRSCI--1 1 Isolators)Isolators)

Joist RSIC Vinyl barrier or ½” soundboard Hat Channel 5/8” sheetrock

38 BackgroundBackground NoiseNoise

BackgroundBackground NoiseNoise

•• InterferesInterferes withwith loudnessloudness perceptionperception •• MasksMasks lowlow levellevel signalssignals andand detaildetail •• TransientTransient noisenoise isis distractingdistracting

39 SourcesSources ofof BackgroundBackground NoiseNoise

•• LocalLocal sourcessources –– HVACHVAC

–– PlumbingPlumbing

–– FansFans

–– Pumps/CompressorsPumps/Compressors

–– Washer/DryersWasher/Dryers

–– GarageGarage doordoor openersopeners

–– ProjectorsProjectors

SourcesSources ofof BackgroundBackground NoiseNoise (continued)(continued)

•• ExternalExternal sourcessources –– TrafficTraffic –– AirplanesAirplanes –– WindWind –– NeighborsNeighbors

40 100

CURRENT (1979) Noise PERMISSIBLE NOISE EXPOSURE Noise PERMISSIBLE NOISE EXPOSURE 90 FOR 8 HOUR DURATION (U.S. DEPT. OF LABOR OSHA) -90 CriteriaCriteria ) ) 2 2 POSSIBLE HEARING POSSIBLE DAMAGE 80 POSSIBLE HEARING DAMAGE N/M N/M Curves (NC)

5 Curves (NC) 5 - - NC-75 -80 NC-70 70 -77 NC-65

-71 Targets: NC-60 -71 Targets: 60 VERY NOISY VERY VERY NOISY VERY NC-55 -66

-61 50 NC-50 -56 NC25NC25 forfor basicbasic NC-45 NOISY NOISY -52 40 NC-40 roomroom NC-35 -47 MODERATE -42 MODERATE 30 NC-30

NC-25 -38 EXPECTED SUBJECTIVE RESPONSE OF RESPONSE SUBJECTIVE EXPECTED TYPICAL BUILDING OCCUPANTS TO THE ENVIRONMENT NOISE EXPECTED SUBJECTIVE RESPONSE OF RESPONSE SUBJECTIVE EXPECTED BUILDINGTYPICAL OCCUPANTS THE TO ENVIRONMENT NOISE QUIET QUIET NC15NC15 forfor HighHigh 20 NC-20 -34 End room NC-15 -30 End room OCTAVE BAND SOUND PRESSURE LEVEL (IN dB RE 2x10 OCTAVE BAND SOUND PRESSURE LEVEL (IN dB RE 2x10 APPROXIMATE THRESHOLD OF NC-10 10 HEARING -26 VERY QUIET VERY FOR CONTINUOUS QUIET VERY NOISE -21 0 63 125 250 500 1000 2000 4000 8000 (IN Dba) OCTAVE BAND CENTER FREQUENCIES (IN HZ) (IN Dba) EQUIVALENT EQUIVALENT EQUIVALENT SOUND LEVEL SOUND LEVEL

MeasuringMeasuring BackgroundBackground NoiseNoise

•• UseUse spectrumspectrum analyzeranalyzer •• UseUse aa lowlow noisenoise microphonemicrophone •• TakeTake aa timetime andand spacespace averageaverage •• UseUse NCNC weightingweighting •• PlugPlug youryour ears,ears, waitwait,, unplugunplug andand listenlisten –– UseUse Earplugs,Earplugs, oror fingersfingers

41 SolutionsSolutions toto BackgroundBackground NoiseNoise

•• LargeLarge airair ductsducts forfor lowerlower airair velocityvelocity •• LongerLonger ductsducts withwith severalseveral turnsturns •• PlenumPlenum silencerssilencers •• LinedLined ductworkductwork •• “Whistle“Whistle Free”Free” airair grillesgrilles •• IsolateIsolate motorsmotors onon suspensionsuspension oror movemove •• CompletelyCompletely sealseal windows,windows, doors,doors, etc.etc.

BackgroundBackground NoiseNoise SummarySummary

•• BackgroundBackground noisenoise degradesdegrades dynamicdynamic range,range, detaildetail clarity,clarity, andand intelligibilityintelligibility •• NoiseNoise cancan bebe detecteddetected withwith testtest instrumentsinstruments oror earplugsearplugs andand earsears •• TreatmentsTreatments includeinclude seals,seals, betterbetter walls,walls, slowerslower air,air, quieterquieter airair handlers,handlers, etc.etc.

42 VibrationVibration ControlControl

RattlesRattles

RattleRattle DetectionDetection

Rattle !!

43 RattlesRattles (continued)(continued)

•• Method:Method: useuse slowslow varyingvarying frequencyfrequency sweepsweep •• CheckCheck –– FurnitureFurniture –– WallsWalls andand DoorsDoors –– GlassGlass SurfacesSurfaces –– FixturesFixtures –– TrackTrack LightsLights –– HVACHVAC DuctsDucts andand VentsVents –– HungHung PicturesPictures –– VentilationVentilation SystemSystem

DecayDecay TimeTime

AkaAkaReverberation Reverberation

44 ReverberationReverberation

•• ReverberationReverberation isis thethe resultresult ofof multiplemultiple reflectionsreflections •• DecayDecay timetime andand spectrumspectrum havehave toto bebe justjust rightright

ReverberationReverberation

•• WhenWhen thethe soundsound hashas bouncedbounced aroundaround thethe roomroom severalseveral timestimes •• NoNo netnet directiondirection oror timetime cuescues remainremain •• SmallSmall roomroom reflectionsreflections diedie outout beforebefore completecomplete reverberationreverberation isis achievedachieved •• WeWe callcall itit decaydecay timetime

45 DecayDecay TimeTime

Decay of an impulse sound LevelLevel

DirectDirect 11stst reflectionsreflections 0dB0dB 22ndnd reflectionsreflections

--30dB30dB

ReverbReverb --60dB60dB

0.10.1 0.20.2 0.30.3 0.40.4 TimeTime

DecayDecay GuidelinesGuidelines

•• DecayDecay timetime shouldshould bebe .2.2 toto .4.4 secondsseconds •• ResearchResearch showsshows thatthat momostst peoplepeople likelike thethe samesame rangerange ofof decaydecay timetime 1/31/3 •• TTmm == 0.30.3 (V/3532)(V/3532) ±±15%15% wherewhere V=roomV=room volumevolume inin ftft33 1/31/3 •• TTmm == 0.30.3 (V/100)(V/100) ±±15%15% where V = room volumevolume inin mm33 •• HandyHandy rulerule ofof thumbthumb forfor projectproject studios,studios, looklook forfor ~25%~25% absorptiveabsorptive wallwall areaarea

46 DecayDecay TimeTime

Criterion 1: Time vs. Volume (500 Hz) RT60RT60 TimeTime

0.31s0.31s

0.28s0.28s

0.25s0.25s

20002000 30003000 40004000 VolumeVolume (ft(ft33))

ToleranceTolerance LimitsLimits forfor DecayDecay TimeTime

Criterion 2: Time vs. Frequency ss

+100%+100%

+66%+66%

200200 HzHz +33%+33% +15%+15% 0 0 TTmm 4kHz --15%15% 4kHz

--50%50% Difference in Reverberation Time Difference in Reverberation Time Difference in Reverberation Time

47 DecayDecay TimeTime GettingGetting itit rightright

•• UseUse thethe rightright amountamount ofof “frictional”“frictional” absorptionabsorption forfor thethe midsmidsand and highshighs •• UseUse thethe rightright amountamount ofof perforatedperforated panelpanel bassbass absorptionabsorption •• CalculateCalculate thethe amountamount withwith thethe Sabine,Sabine, EyringEyring oror ArauArau-- Puchades Puchadesequations equations –– KnowKnow thethe absorptionabsorption cocoefficientefficient ofof materialsmaterials

–– BeBe preparedprepared toto dodo lotslots ofof mathmath

DecayDecay TimeTime GettingGetting itit rightright

•• TheThe SabineSabine equation:equation: GoodGood butbut oldold 0.049V V is volume RT60 = S is absorption surface area a is absorption coefficient Stotala •• TheThe EyringEyringequation: Better andand moremore recentrecent

0.049V RT60 = V is volume -S ln(1-A) S is total room surface area A is area-weighted averaged absorption coefficient

48 DecayDecay TimeTime GettingGetting itit rightright

•• TheThe ArauArau-- Puchades Puchadesequation: equation: BestBest andand latestlatest

x/s y/s z/s 0.161V 0.161V 0.161V RT60 = x x [ ] [ ] [ -S ln(1-α )] [ -S ln(1-α )] -S ln(1-αx) -S ln(1-αy) z

V is volume S is total room surface area α is area-weighted averaged absorption coefficient for each wall x is area of Left +Right walls y is area of Front + Rear walls z is area of Floor + Ceiling

DecayDecay TimeTime GettingGetting itit rightright

•• SpreadSpread absorptionabsorption materialsmaterials aroundaround thethe roomroom surfacessurfaces •• AlsoAlso useuse diffusiondiffusion toto smoothsmooth outout decaydecay •• DiffusionDiffusion enhancesenhances absorptionabsorption effectivenesseffectiveness

49 PlacingPlacing TreatmentTreatment MaterialsMaterials

SoundSound ReflectionsReflections

ReflectionsReflections == DistortionDistortion

50 RoomRoom ReflectionsReflections

Loudspeaker •• ReflectionsReflections causecause

th Re –– Blurring of image Pa fle Blurring of image d ct te ed h flec t Pa – Spectral imbalance a t – Spectral imbalance Re h

t by comb filtering c by comb filtering

Listener

RoomRoom ReflectionsReflections CombComb FilterFilter EffectEffect (Part(Part 1)1)

tt11 tt22

DirectDirect

AnAn AdditiveAdditive ReflectedReflected FrequencyFrequency

Result:Result: (+6dB)(+6dB) tt11

tt22 DirectDirect

AA CancelingCanceling ReflectedReflected FrequencyFrequency

51 RoomRoom ReflectionsReflections CombComb FilterFilter EffectEffect (Part(Part 2)2) Resultant Frequency Response from Reflection

SoundSound LevelLevel

+6dB+6dB

0dB0dB

FrequencyFrequency PeakPeak andand dipsdips atat variousvarious frequenciesfrequencies

RoomRoom ReflectionsReflections CombComb FilterFilter EffectEffect (Part(Part 3)3) Resultant Frequency Response from Shorter Reflection

SoundSound LevelLevel

+6dB+6dB

0dB0dB

FrequencyFrequency PeakPeak andand dipsdips atat higherhigher frequenciesfrequencies thanthan previousprevious exampleexample

52 RoomRoom ReflectionsReflections DidDid youyou Know?!Know?!

•• AtAt mainmain seatseat youyou listenlisten toto Critical moremore reflectedreflected soundsound than Distance direct!direct! •• ““CriticalCritical Distance”Distance” isis wherewhere directdirect soundsound andand reflectedreflected soundsound energyenergy areare equalequal- - aboutabout 44 feetfeet inin untreateduntreated roomsrooms •• NeedNeed toto movemove CriticalCritical DistanceDistance closercloser toto listenerlistener

RoomRoom ReflectionsReflections DetectionDetection MethodsMethods

Loudspeaker •• MirrorMirror

Mirror –– MoveMove aa mirrormirror upup andand downdown sideside wallwall andand findfind locationlocation wherewhere speakerspeaker isis visiblevisible Look for speaker in mirror –– ThisThis couldcould bebe anan offendingoffending reflectionreflection Listener pointpoint

53 RoomRoom ReflectionsReflections DetectionDetection MethodsMethods (continued)(continued)

Loudspeaker playing pink •• ChangingChanging combcomb filtersfilters noise –– PlayPlay pinkpink noisenoise fromfrom speakerspeaker

–– Move head location lo Move head location ng er s pa leftleft-to-right-to-right ho th rte r pa th –– ListenListen forfor changingchanging combcomb filters,filters, oror higher pitch Lower pitch “phasiness”“phasiness”

SolutionsSolutions toto RoomRoom ReflectionsReflections AbsorptionAbsorption

54 SolutionsSolutions toto RoomRoom ReflectionsReflections AbsorptionAbsorption

Loudspeaker •• AbsorptiveAbsorptive materialsmaterials – Fiberglass th Re – Fiberglass Pa fle d ct te ed – Dense foam h P – Dense foam flec t a Re a th

P –– DraperiesDraperies t

r i –– StuffedStuffed chairschairs

D Absorptive Absorptive • “Scrub” off acoustic Material Material • “Scrub” off acoustic energyenergy throughthrough Listener frictionfriction •• TreatTreat thethe ceilingceiling too!too!

AcousticalAcoustical TreatmentsTreatments AbsorptionAbsorption ThicknessThickness

•• 1”1” PanelsPanels workwork downdown toto 1kHz1kHz •• 2”2” PanelsPanels workwork downdown toto 500Hz500Hz (better)(better) •• 4”4” PanelsPanels workwork downdown toto 250Hz250Hz (best)(best)

Absorption 4” 2” 1”

250Hz 500Hz 1kHz Frequency

55 ““Floating”Floating” anan AbsorptionAbsorption PanelPanel

Absorption 1st Absorption Absorption on wall - On wall Only higher frequency reflections are affected

Away from wall Source Absorption away from wall High and low frequencies are tamed

More LF’s absorbed Frequency

AcousticalAcoustical TreatmentsTreatments NotesNotes onon AbsorptionAbsorption

•• Don’tDon’t “over“over absorb”absorb” –– DeadDead roomsrooms soundsound oddodd –– TargetTarget soundsound reflectionreflection decaydecay time:time: 0.3s0.3s –– 25%25% coveragecoverage ofof wallwall surfacesurface

56 AcousticalAcoustical TreatmentsTreatments NotesNotes onon DraperiesDraperies

•• DraperiesDraperies areare unevenuneven acousticalacoustical absorbersabsorbers •• PerformancePerformance affectedaffected byby fabricfabric weight,weight, pleatpleat number,number, distancedistance fromfrom boundaryboundary •• AtAt leastleast 3”3” airair gapgap •• VelourVelour massmass 3232 ouncesounces perper lineallineal yardyard •• 100%100% fullnessfullness

LowLow FrequencyFrequency ReflectionsReflections

PlacingPlacing SpeakersSpeakers

57 BoundaryBoundary EffectsEffects Loudspeaker/Loudspeaker/ RoomRoom InteractionsInteractions

•• ReflectionReflection issuesissues atat lowlow frequenciesfrequencies areare calledcalled “boundary“boundary effects”effects” •• PeaksPeaks andand dipsdips inin bass/midbass/mid frequenciesfrequencies dependdepend onon speakerspeaker locationlocation •• LowLow frequenciesfrequencies areare hardhard toto absorbabsorb

LowLow FrequencyFrequency ReflectionsReflections StrategiesStrategies

•• FirstFirst reducereduce peak/dippeak/dip errorserrors throughthrough properproper placementplacement •• “Resistive”“Resistive” AbsorbersAbsorbers tootoo thickthick •• UseUse HelmholtzHelmholtz andand DiaphragmDiaphragm methodsmethods •• EqualizeEqualize

58 FrontFront SpeakerSpeaker PlacementPlacement UnequalUnequal BoundariesBoundaries

Unequal Reflected Path Lengths

FrontFront SpeakerSpeaker PlacementPlacement (continued)(continued)

•• AimAim forfor unequalunequal reflectionreflection pathpath lengthslengths forfor floorfloor // sideside // frontfront wallwall •• DistributeDistribute errorserrors

Side Floor Front

59 SolutionsSolutions toto LFLF ReflectionsReflections BassBass AbsorptionAbsorption

•• UseUse PerforatedPerforated woodwood surfacesurface onon boxbox •• TuningTuning equation:equation:

p ƒ = 200 0 (d) (t)

Solutions to LF Reflections Bass Absorption

•• WithWith BassBass absorber,absorber, SideSide wallwall responseresponse isis smoothersmoother •• TheThe remainingremaining errorerror cancan bebe equalizedequalized Front Floor Side •• CanCan alsoalso useuse BassBass absorbersabsorbers onon frontfront wallwall

60 SolutionsSolutions toto LFLF ReflectionsReflections BassBass AbsorptionAbsorption onon thethe frontfront wallwall

• Use Bass absorber to kill front wall reflection

SolutionsSolutions toto LFLF ReflectionsReflections AA BassBass AbsorberAbsorber

3/4” MDF backing board

Framing

1” 3pcf fiberglass

Perforated Board

Fabric

61 BoundaryBoundary EffectsEffects

•• EvaluationEvaluation •• CorrectionCorrection –– ComputerComputer predictionspredictions –– AvoidAvoid multiplemultiple equalequal boundaryboundary •• CARACARA distancesdistances •• RPGRPG RoomRoom optimizeroptimizer –– ChangeChange speakerspeaker positionposition –– UseUse circulatingcirculating pinkpink noisenoise –– MatchMatch boundaryboundary conditionsconditions forfor andand listenlisten forfor timbraltimbral thethe frontfront speakersspeakers variationsvariations –– FlushFlush mountmount speakersspeakers –– UseUse pinkpink noisenoise andand RTARTA toto –– UseUse lowlow frequencyfrequency absorptionabsorption measuremeasure spectralspectral – Equalize variationsvariations – Equalize

ReflectionReflection ControlControl

DiffusionDiffusion

62 SolutionsSolutions toto RoomRoom ReflectionsReflections DiffusionDiffusion

SolutionsSolutions toto RoomRoom ReflectionsReflections DiffusionDiffusion

Loudspeaker •• DiffusiveDiffusive materials h R at ef P lec ed te –– PurposePurpose--bbuiltuilt ct d fle Pa e h th R t panelspanels

t c –– Bookcase e Bookcase

D DiffuserDiffuser DiffuserDiffuser

Listener

63 AcousticalAcoustical TreatmentsTreatments DiffusionDiffusion

•• NeedNeed enoughenough diffusiondiffusion surfacesurface toto “smooth“smooth out”out” thethe soundfieldsoundfield •• BalanceBalance diffusiondiffusion andand absorptionabsorption •• KeepKeep somesome livenesslivenessto to thethe room

AcousticalAcoustical TreatmentsTreatments DiffusionDiffusion typestypes

•• 2D2D diffusiondiffusion redistributesredistributes incidentincident soundsound toto aa planeplane –– UseUse alongalong frontfront portionportion ifif sideside wallswalls toto diffusediffuse frontfront speakersspeakers •• 3D3D diffusiondiffusion redistributesredistributes soundsound toto aa hemispherehemisphere –– UseUse itit towardstowards thethe rearrear ofof roomroom forfor surroundsurround speakersspeakers

64 AcousticalAcoustical TreatmentsTreatments DiffusionDiffusion ––2D 2D DiffusersDiffusers

Cylindrical

Slotted

AcousticalAcoustical TreatmentsTreatments DiffusionDiffusion --3D 3D DiffusersDiffusers

65 AcousticAcoustic TreatmentTreatment ManufacturersManufacturers

•• StudioPanelStudioPanel •• RPGRPG •• AcousticsAcoustics FirstFirst •• KineticsKinetics NoiseNoise ControlControl •• AuralexAuralex •• AndAnd manymany others!others!

SlapSlap EchoesEchoes

66 SlapSlap EchoesEchoes

•• EchoesEchoes are Loudspeaker –– RepeatedRepeated reflectionsreflections betweenbetween twotwo parallelparallel surfacessurfaces •• SlapSlap echoesechoes causecause –– Bright,Bright, “zingy”“zingy” soundsound Listener –– InterferenceInterference withwith acousticacoustic charactercharacter ofof soundsound –– TimbralTimbral changeschanges

SlapSlap EchoesEchoes DetectionDetection MethodsMethods

•• ClapClap handshands atat variousvarious locationslocations inin roomroom •• ListenListen forfor echoecho •• IfIf possible,possible, sitsit atat primaryprimary seatseat andand listenlisten toto aa personperson clappingclapping atat variousvarious locationslocations

67 SolutionsSolutions toto EchoesEchoes MaterialsMaterials

•• AbsorptiveAbsorptive Loudspeaker –– FiberglassFiberglass panelspanels

–– FoamFoam panelspanels

–– DrapesDrapes Listener •• DiffusiveDiffusive –– DiffuserDiffuser panelspanels

–– BookcasesBookcases

–– FurnitureFurniture Absorber Diffuser

PlacingPlacing listenerslisteners

Don’tDon’t sitsit atat resonanceresonance peakspeaks oror dipsdips

68 .8 *L .68 *L.55 *L .45 *L .32 *L .2 *L SolutionsSolutions .8 *H .68 *H .55 *H toto StandingStanding .45 *H .32 *H WavesWaves .2 *H SeatingSeating 63 251 314 188 126 27 PlacementPlacement 54 81 108 135 71 35 106 141 176

.2 *W

.32 *W

.45 *W

.55 *W

.68 *W

.8 *W

Listener/SpeakerListener/Speaker placementplacement

•Position Left and Right to form a 45 degree angle to seating area

45º •Balance between stereo phantom image and multichannel separation

69 ExampleExample LayoutLayout

ExampleExample TreatmentTreatment LayoutLayout

A B CinePanel 2D Diffuser

2D Diffusion Door with absorber panel 2’x7’ 130Hz 3D Diffuser Bass absorber unit

5x10’ Absorption CinePanel Absorptive panel on central ceiling section 107Hz Bass absorption units 3D Diffusion In upper 2’x4’ 2” Absorption panels areas 130Hz Bass absorption units

C D

70 ExampleExample TreatmentTreatment LayoutLayout LeftLeft WallWall

D C

Surround speaker

Cylindrical Diffuser CinePanel Diffuseur Acoustic Innovations 2ftx2ft 2ftx4ft

CinePanel Absorber 107Hz Diaphragmatic Absorber 2ftx4ft 2ftx5ft

ExampleExample TreatmentTreatment LayoutLayout RightRight WallWall

A B

Surround speaker

Cylindrical Diffuser CinePanel Diffuseur Acoustic Innovations 2ftx2ft 2ftx4ft

CinePanel Absorber 107Hz Diaphragmatic Absorber 2ftx4ft 2ftx5ft

71 ExampleExample TreatmentTreatment LayoutLayout FrontFront WallWall

A C

Cylindrical Diffuser Acoustic Innovations 2ftx2ft 130Hz Diaphragmatic Absorber CinePanel Absorber 2ftx5ft 2ftx4ft

ExampleExample TreatmentTreatment LayoutLayout RearRear WallWall

A C

Rear speaker

Cylindrical Diffuser CinePanel Diffuseur Acoustic Innovations 2ftx2ft 2ftx4ft

CinePanel Absorber 3D Diffuser 2ftx4ft Acoustic Innovations 2ftx2ft

72 TuningTuning itit AllAll

AnalysisAnalysis andand equalizationequalization

LevelLevel CalibrationCalibration

•• UseUse midbandmidbandpink pink noisenoise signalssignals –– referencereference diskdisk oror internalinternal testtest tonestones

Level Mid-Frequency test noise internal to most good surround processors. The signal is centered in the 500Hz to 2kHz region to improve measurement accuracy

500Hz 2kHz Frequency

73 AnalysisAnalysis ––the the usefuluseful wayway

Microphone 4 Analyzer,Analyzer, oror

Microphone 1 equivalentequivalent

FrequencyFrequency ResponseResponse CalibrationCalibration RoomRoom ++ EqualizerEqualizer PhasePhase ResponseResponse •• 1212 dBdB peakpeak errorerror atat 200200 HzHz (yellow(yellow line)line) •• PhasePhase errorerror (red(red line)line) •• EqualEqual cutcut introducesintroduces inverseinverse phasephase errorerror •• AmplitudeAmplitude andand phasephase areare corrected!corrected!

74 EqualizationEqualization RequirementsRequirements

•• PinkPink noisenoise sourcesource –– 2020 HzHz–20–20 kHz, switchableswitchableto to eacheach channelchannel beforebefore thethe crossovercrossover (5.1(5.1 AudioAudio Toolkit)Toolkit) •• RealReal timetime analyzeranalyzer –– 2020 secondsecond timetime averagingaveraging –– TheThe abilityability toto averageaverage 4 or more readings fromfrom micmicmultiplexing multiplexing –– 1/121/12 octave resolution in low frequenciesfrequencies

QuickQuick CheckCheck ofof OverallOverall FrequencyFrequency ResponseResponse

Using Etymotic ER- 4S or ER-6 Earphones

Pink Pink Noise Noise

Compare CD CD

Set earphone level to match speaker

75 ToolsTools

UlyssesUlysses

76 SMAARTSMAART LiveLive

GoldGold LineLine DSP30DSP30

•• RTARTA •• 1/3,1/3, 1/6,1/6, 1/121/12thth OctaveOctave •• AveragingAveraging •• NCNC •• RT60RT60 •• IntegratedIntegrated solutionsolution

77 TEFTEF 20002000

•• RTARTA •• TEFTEF •• MLSSAMLSSA •• LogLog sweepssweeps •• PhasePhase measurementsmeasurements •• ManyMany moremore

GoodGood ReadingReading MaterialsMaterials

•• AcousticsAcoustics andand PsychoacousticsPsychoacoustics,, Howard,Howard, DavidDavid M.,M., Angus,Angus, James,James, FocalFocal Press,Press, 1996,1996, ISBNISBN 00 240240 5148251482 99 •• AudioAudio EngineeringEngineering HandbookHandbook,, Benson,Benson, K.K. BlairBlair ed.ed. McGrawMcGraw-Hill-Hill BookBook Company,Company, 19881988 •• BuildingBuilding aa RecordingRecording StudioStudio,, Cooper,Cooper, Jeff,Jeff, SynergySynergy Group,Group, Inc.,Inc., LosLos Angeles.Angeles. ToTo orderorder callcall 11-800-468-4322-800-468-4322 •• TheThe MasterMaster HandbookHandbook ofof AcousticsAcoustics,, Everest,Everest, F.F. Alton,Alton, TABTAB Books,Books, Division of McGrawMcGraw-Hill-Hill Inc., Blue Ridge Summit, PA.PA. ToTo orderorder callcall 11-800-468-4322-800-468-4322 •• ProjectProject StudiosStudios,, P.P. Newell,Newell, FocalFocal Press,Press, ISBNISBN 00 240240 5157351573 00 •• RoomRoom AcousticsAcoustics,, KuttruffKuttruff,, Heinrich,Heinrich, AppliedApplied ScienceScience PublishersPublishers 1973/19911973/1991

78 SummarySummary

•• RoomRoom acousticsacoustics affectaffect anyany audioaudio systemsystem •• LookLook outout forfor reflections,reflections, echoes,echoes, boundaries,boundaries, reverberation,reverberation, standing waves, rattles,rattles, noise,noise, andand soundsound isolationisolation •• WithWith basicbasic sciencescience andand carecare youyou tootoo cancan tametame roomroom acoustics.acoustics. •• ThanksThanks forfor listening,listening, AnthonyAnthony GrimaniGrimani

ContactContact InfoInfo

AnthonyAnthony GrimaniGrimani PMI,PMI, LtdLtd 9A9A MonoMono AvenueAvenue Fairfax,Fairfax, CACA 9493094930 [email protected]@pmiltd.com 415415 454454 20872087 www.pmiltd.comwww.pmiltd.com