Trane TRG-TRC007-EN manual Insertion loss IL Noise reduction NR Transmission loss TL

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period three

Acoustical Analysis

notes

Sound Transmission

IInsertion loss (IL)

INoise reduction (NR)

ITransmission loss (TL)

Figure 48

The ability of a material to reduce transmitted sound is most commonly referred to in terms of its insertion loss, noise reduction, or transmission loss. Insertion loss and noise reduction are both based on actual sound-pressure measurements and are expressed in terms of dB reduction.

Insertion loss (IL) is the difference in sound pressure measured in a single location with and without a noise-control device located between the source and receiver. Using the air-handler example (Figure 42), assume there is a door installed in the wall separating the equipment room from the office space. The difference in the sound pressure measured in the occupied space with the door open versus with the door closed is the IL of the door.

Noise reduction (NR) is the difference between sound-pressure measurements taken on each side of a barrier. For example, the NR for this same door can be determined by measuring the sound-pressure level inside the office space, with the door closed, and on the other side of the door inside the equipment room. The difference in these measurements is the NR of the door.

Transmission loss (TL) is proportional to the ratio of the sound-power level on the receiver side of a barrier to the sound-power level on the source side. Using the same door example, the transmission loss of the door is determined by the manufacturer by taking measurements in a special laboratory and expressing the results as sound power. It is also expressed in terms of dB reduction.

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Contents Air Conditioning Clinic Fundamentals of Hvac Acoustics Business Reply Mail Comment Card One of the Fundamental SeriesFundamentals of Hvac Acoustics Preface Fundamentals of Hvac AcousticsContents TRG-TRC007-EN Fundamentals of Sound Fundamentals of SoundWhat is Sound? What is Sound?Sound Wave and Frequency Wavelength Broadband Sound Broadband Sound and TonesOctave Bands Octave BandsLogarithmic sums One-Third Octave Bands Sound Power and Sound Pressure Sound Power and Sound PressureAn Analogy DB = 10 log DecibelLogarithmic Scale 10 ´ logEquation for Sound Power Equation for Sound PressureLogarithmic Addition of Decibels 50 dB + 44 dB = 51 dBHuman Ear Response Sound Perception Rating MethodsHuman Ear Loudness Contours Single-Number Rating Methods Response to TonesSingle-Number Rating Methods C Weighting Sound Perception and Rating MethodsWeighting Example Weighting Noise Criteria NC Curves NC-39 Room Criteria RC Curves MPa DB ref Pressure Sound Perception and Rating Methods RC-31 R Phon and Sone Octave-Band Rating Method Octave-Band Rating MethodAcoustical Analysis Acoustical AnalysisSetting a Design Goal Setting a Design GoalAcoustical Analysis Acoustical Analysis Source-Path-Receiver AnalysisSource-Path-Receiver Model Typical Sound Paths AirborneExamples of a Single Sound Path Example of Multiple Sound PathsIdentifying Sound Sources and Paths Modeling Sound Paths Sound-Path ModelingSupply Algorithms for Sound-Path Modeling Computerized Analysis Tools Attenuation and Regeneration Terms Used in Sound-Path ModelingSound Transmission Insertion loss IL Noise reduction NR Transmission loss TL Absorption Reflected Sound Receiver Sound Correction Equipment Sound Rating Equipment Sound RatingFree Field Fields of Measurement= L p1 20 log Distance Correction in a Free FieldLot Near Field Reverberant Field Semireverberant Field Rating Hvac Equipment Hvac Equipment Sound RatingReverberant-Room Method Free-Field Method Industry Standards Ducted Air-Handling Equipment Air Handler Test Configurations Former Methods of Sound Testing ARI Standard Sound Power by Octave Band Review Review-Period OneReview-Period Two Noise criteria NC Room criteria RCReview-Period Three Review-Period Four Review Quiz Questions for PeriodOctave-band frequency, Hz Answers Glossary Glossary Room effect See receiver room correction Glossary Trane