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Trane TRG-TRC007-EN manual Fundamentals of Sound, period one, Octave Bands

Models: TRG-TRC007-EN

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Octave 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.

period one

Fundamentals of Sound

notes

Octave Bands

logarithmic sums

amplitude

63 125 250 500 1,000 2,000 4,000 8,000

frequency, Hz	Figure 9

Octave 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.

Unfortunately, octave bands do not indicate that the human ear hears a difference between an octave that contains a tone and one that does not, even when the overall magnitude of both octaves is identical. Therefore, the process of logarithmically summing sound measurements into octave bands, though practical, sacrifices valuable information about the “character” of the sound.

TRG-TRC007-EN

Page 14

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Trane TRG-TRC007-EN manual Fundamentals of Sound, period one, Octave Bands

Contents

One of the Fundamental Series Air Conditioning ClinicFundamentals of HVAC Acoustics TRG-TRC007-ENTRANE Attn Applications Engineering BUSINESS REPLY MAILBUSINESS REPLY MAIL 3600 Pammel Creek Road La Crosse WIFundamentals of HVAC Comment CardResponse Card AcousticsFundamentals 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 three Contentsperiod two Sound Perception and Rating Methods period fiveTRG-TRC007-EN Fundamentals of Sound period oneFundamentals of Sound period oneWhat is Sound? What is Sound?period one Fundamentals of Soundperiod one Sound Wave and FrequencyFundamentals of Sound period one WavelengthFundamentals of Sound Fundamentals of Sound Broadband SoundBroadband Sound and Tones period oneperiod one Octave BandsFundamentals of Sound Octave BandsOctave Bands Fundamentals of Soundperiod one Octave 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 bandperiod one One-ThirdOctave BandsFundamentals of Sound Fundamentals of Sound Sound Power and Sound PressureSound Power and Sound Pressure period oneperiod one An AnalogyFundamentals of Sound K Correlates to bulb wattageFundamentals of Sound dB = 10 log10Decibel period oneperiod one Logarithmic ScaleFundamentals of Sound ratio= 20 log10 Equation for Sound Power= 10 log10 Equation for Sound PressureFundamentals of Sound Logarithmic Addition of Decibels50 dB + 44 dB = 51 dB period oneSound Perception and Rating Methods period twoSound Perception and Rating Methods period twoSound Perception and Rating Methods period twoLoudness Contours Sound Perception and Rating Methods Response to TonesSingle-NumberRating Methods period twoperiod 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 Noise Criteria NC Curves Sound Perception and Rating Methodsperiod two NC-39period two Room Criteria RC CurvesSound Perception and Rating Methods Room Criteria RC Curves Sound Perception and Rating Methodsperiod two dB refnPerceptible 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 Room Criteria RC Curves Sound Perception and Rating Methodsperiod two RC-31Rperiod two Phon and SoneSound Perception and Rating Methods period two Octave-BandRating MethodSound Perception and Rating Methods Octave-BandRating MethodAcoustical Analysis period threeAcoustical Analysis period threeSetting a Design Goal Setting a Design Goalperiod three Acoustical AnalysisAcoustical Analysis 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 period threeperiod three Acoustical AnalysisAcoustical Analysis Source-Path-ReceiverAnalysisperiod three Source-Path-ReceiverModelAcoustical Analysis period three Typical Sound PathsAcoustical Analysis IAirborneAcoustical Analysis Examples of a Single Sound PathExample of Multiple Sound Paths period threeperiod three Identifying Sound Sources and PathsAcoustical Analysis packaged rooftop air conditionerperiod three Modeling Sound PathsAcoustical Analysis Sound-PathModelingExample of Multiple Sound Paths Acoustical Analysisperiod three supplyperiod three Algorithms for Sound-PathModelingAcoustical Analysis period three Computerized Analysis ToolsAcoustical Analysis period three Attenuation and RegenerationAcoustical Analysis Terms Used in Sound-PathModelingperiod three Sound TransmissionAcoustical Analysis Sound Transmission Acoustical Analysisperiod three IInsertion loss IL INoise reduction NRperiod three AbsorptionAcoustical Analysis period three Reflected SoundAcoustical Analysis period three Receiver Sound CorrectionAcoustical Analysis Equipment Sound Rating period fourEquipment Sound Rating period fourEquipment Sound Rating period fourFree Field Fields of MeasurementDistance Correction in a Free Field = Lp120 log10 Equipment Sound RatingDistance Correction in a Free Field Equipment Sound Ratingperiod four Lp2 = 95 dB - 20 log10 120 ft / 30 ft = 83 dBperiod four Near FieldEquipment Sound Rating period four Reverberant FieldEquipment Sound Rating source reflective wallsperiod four Semireverberant FieldEquipment Sound Rating period four Rating HVAC EquipmentEquipment Sound Rating HVAC Equipment Sound Ratingperiod four Reverberant-RoomMethodEquipment Sound Rating period four Free-FieldMethodEquipment Sound Rating period four Industry StandardsEquipment Sound Rating period four Ducted Air-HandlingEquipmentEquipment Sound Rating supply-airoutletperiod four Air Handler Test ConfigurationsEquipment Sound Rating period four Former Methods of Sound TestingEquipment Sound Rating I ASHRAE generic fan algorithmperiod four ARI StandardEquipment Sound Rating IUses reverberant- room methodperiod four Sound Power by Octave BandEquipment Sound Rating 1 2 3Review period fiveReview period fiveReview period fiveReview-PeriodTwo TRG-TRC007-ENperiod five Review-PeriodThreeReview period five Review-PeriodFourReview nTrane Acoustics Program TAP Reviewperiod five Questions for Period QuizQuestions for Period Questions for Period QuizQuestions for Period 7True or False Sound can only travel from a source to the receiver along one pathAnswers Glossary Glossary hertz Hz The unit of measure for frequency. One hertz is equal to one cycle per secondGlossary reverberant 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 pointsGlossary the receiver, and everything it encounters as it travels along the way, constitutes the pathFile Number Literature Order NumberTRG-TRC007-EN E/AV-FND-TRG-TRC007-1101-EN