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Trane TRG-TRC007-EN manual Reverberant Field, Equipment Sound Rating, period four

Models: TRG-TRC007-EN

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period four

Equipment Sound Rating

notes

Reverberant Field

source

reflective walls

Figure 57

A reverberant field is nearly the opposite of a free field. Reverberant fields exist in rooms with reflective walls, floors, and ceilings. When a sound source is placed in an enclosed room, the sound waves from the source bounce back and forth between the reflective walls many times. This can create a uniform, or diffuse, sound field. In a perfectly reverberant room, the sound-pressure level is equal at all points within the room.

Special reverberant rooms are designed, built, and qualified for the purpose of measuring the sound emitted by a piece of equipment. This type of facility will be discussed later in this period.

52	TRG-TRC007-EN

Page 59

Image 59

Trane TRG-TRC007-EN manual Reverberant Field, Equipment Sound Rating, period four, source reflective walls

Contents

TRG-TRC007-EN Air Conditioning ClinicFundamentals of HVAC Acoustics One of the Fundamental Series3600 Pammel Creek Road La Crosse WI BUSINESS REPLY MAILBUSINESS REPLY MAIL TRANE Attn Applications EngineeringAcoustics Comment CardResponse Card Fundamentals of HVACFundamentals of HVAC Acoustics One of the Fundamental Series A publication ofTrane, an American Standard Company A Trane Air Conditioning Clinic PrefaceFundamentals of HVAC Acoustics period five Contentsperiod two Sound Perception and Rating Methods period threeTRG-TRC007-EN period one period oneFundamentals of Sound Fundamentals of SoundFundamentals of Sound What is Sound?period one What is Sound?period one Sound Wave and FrequencyFundamentals of Sound period one WavelengthFundamentals of Sound period one Broadband SoundBroadband Sound and Tones Fundamentals of SoundOctave Bands Octave BandsFundamentals of Sound period oneOctave bands compress the range of frequencies between the upper and lower ends of the band into a single value. Sound measured in an octave band is the logarithmic sum of the sound level at each of the frequencies within the band Fundamentals of Soundperiod one Octave Bandsperiod one One-ThirdOctave BandsFundamentals of Sound period one Sound Power and Sound PressureSound Power and Sound Pressure Fundamentals of SoundK Correlates to bulb wattage An AnalogyFundamentals of Sound period oneperiod one dB = 10 log10Decibel Fundamentals of Soundratio Logarithmic ScaleFundamentals of Sound period oneEquation for Sound Pressure Equation for Sound Power= 10 log10 = 20 log10period one Logarithmic Addition of Decibels50 dB + 44 dB = 51 dB Fundamentals of Soundperiod two period twoSound Perception and Rating Methods Sound Perception and Rating MethodsSound Perception and Rating Methods period twoLoudness Contours period two Response to TonesSingle-NumberRating Methods Sound Perception and Rating Methodsperiod two A-B-CWeightingSound Perception and Rating Methods period two A-WeightingExampleSound Perception and Rating Methods period two A-WeightingSound Perception and Rating Methods period two Noise Criteria NC CurvesSound Perception and Rating Methods NC-39 Sound Perception and Rating Methodsperiod two Noise Criteria NC Curvesperiod two Room Criteria RC CurvesSound Perception and Rating Methods dB ref Sound Perception and Rating Methodsperiod two Room Criteria RC CurvesnPerceptible vibration RV The sound level in the octave bands between 16 Hz and 63 Hz falls in the shaded regions A and B. These regions indicate sound-pressurelevels at which walls and ceilings can vibrate perceptibly-rattlingcabinet doors, pictures, ceiling fixtures, and other furnishings in contact with them Sound Perception and Rating Methodsperiod two RC-31R Sound Perception and Rating Methodsperiod two Room Criteria RC Curvesperiod two Phon and SoneSound Perception and Rating Methods Octave-BandRating Method Octave-BandRating MethodSound Perception and Rating Methods period twoperiod three period threeAcoustical Analysis Acoustical AnalysisAcoustical Analysis Setting a Design Goalperiod three Setting a Design Goalperiod three Setting a Design GoalWhen defining the acoustical design goal for an outdoor environment, to meet a local noise ordinance for example, the A-weightedscale is typically used. This generally takes the form of a maximum A-weighted sound-pressurelevel at the lot line of the property Acoustical AnalysisSource-Path-ReceiverAnalysis Acoustical AnalysisAcoustical Analysis period threeperiod three Source-Path-ReceiverModelAcoustical Analysis IAirborne Typical Sound PathsAcoustical Analysis period threeperiod three Examples of a Single Sound PathExample of Multiple Sound Paths Acoustical Analysispackaged rooftop air conditioner Identifying Sound Sources and PathsAcoustical Analysis period threeSound-PathModeling Modeling Sound PathsAcoustical Analysis period threesupply Acoustical Analysisperiod three Example of Multiple Sound Pathsperiod three Algorithms for Sound-PathModelingAcoustical Analysis period three Computerized Analysis ToolsAcoustical Analysis Terms Used in Sound-PathModeling Attenuation and RegenerationAcoustical Analysis period threeperiod three Sound TransmissionAcoustical Analysis IInsertion loss IL INoise reduction NR Acoustical Analysisperiod three Sound Transmissionperiod three AbsorptionAcoustical Analysis period three Reflected SoundAcoustical Analysis period three Receiver Sound CorrectionAcoustical Analysis period four period fourEquipment Sound Rating Equipment Sound RatingFields of Measurement period fourFree Field Equipment Sound RatingEquipment Sound Rating = Lp120 log10 Distance Correction in a Free FieldLp2 = 95 dB - 20 log10 120 ft / 30 ft = 83 dB Equipment Sound Ratingperiod four Distance Correction in a Free Fieldperiod four Near FieldEquipment Sound Rating source reflective walls Reverberant FieldEquipment Sound Rating period fourperiod four Semireverberant FieldEquipment Sound Rating HVAC Equipment Sound Rating Rating HVAC EquipmentEquipment Sound Rating period fourperiod four Reverberant-RoomMethodEquipment Sound Rating period four Free-FieldMethodEquipment Sound Rating period four Industry StandardsEquipment Sound Rating supply-airoutlet Ducted Air-HandlingEquipmentEquipment Sound Rating period fourperiod four Air Handler Test ConfigurationsEquipment Sound Rating I ASHRAE generic fan algorithm Former Methods of Sound TestingEquipment Sound Rating period fourIUses reverberant- room method ARI StandardEquipment Sound Rating period four1 2 3 Sound Power by Octave BandEquipment Sound Rating period fourperiod five period fiveReview ReviewTRG-TRC007-EN period fiveReview-PeriodTwo Reviewperiod five Review-PeriodThreeReview period five Review-PeriodFourReview nTrane Acoustics Program TAP Reviewperiod five Questions for Period QuizQuestions for Period 7True or False Sound can only travel from a source to the receiver along one path QuizQuestions for Period Questions for PeriodAnswers Glossary hertz Hz The unit of measure for frequency. One hertz is equal to one cycle per second Glossaryreverberant field A uniform, or diffuse, sound field that is the opposite of a free field. In a perfectly reverberant field, the sound-pressurelevel is equal at all points Glossarythe receiver, and everything it encounters as it travels along the way, constitutes the path GlossaryE/AV-FND-TRG-TRC007-1101-EN Literature Order NumberTRG-TRC007-EN File Number