Trane TRG-TRC007-EN manual Identifying Sound Sources and Paths

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period three

Acoustical Analysis

notes

1Supply airborne through the supply ductwork and diffusers and into the space

2Supply breakout as the sound travels through the walls of the supply ductwork, through the ceiling tile, and into the space

3Return airborne through the air-handler intake, return ductwork and grilles, and into the space

4Wall transmission as the sound travels through the adjoining wall and into the space

These paths are typical of most centralized air-handling equipment, including packaged rooftop and self-contained air conditioners. Most other equipment types have a subset of these paths.

Identifying Sound Sources and Paths

IOne piece of equipment may contain several sound sources

ISound may travel from source to receiver along multiple paths

ITotal sound heard by the receiver is the sum of all sounds from all sources and all paths

packaged rooftop air conditioner

Figure 41

There are a few important points to remember when identifying sources and paths for a source–path–receiver acoustical analysis.

nOne piece of equipment may contain several sound sources. For example, a packaged rooftop air conditioner (shown in Figure 41) contains supply and exhaust (or return) fans, compressors, and condenser fans.

nSound may travel from a single source to the receiver along multiple paths. This was demonstrated with the previous example.

nThe total sound heard by the receiver is the sum of all the sounds from various sources that travel along several paths.

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Contents Air Conditioning Clinic Fundamentals of Hvac Acoustics Business Reply Mail One of the Fundamental Series Comment CardFundamentals of Hvac Acoustics Fundamentals of Hvac Acoustics PrefaceContents TRG-TRC007-EN Fundamentals of Sound Fundamentals of SoundWhat is Sound? What is Sound?Sound Wave and Frequency Wavelength Broadband Sound and Tones Broadband SoundOctave Bands Octave BandsLogarithmic sums One-Third Octave Bands Sound Power and Sound Pressure Sound Power and Sound PressureAn Analogy Decibel DB = 10 log10 ´ log Logarithmic ScaleEquation for Sound Pressure Equation for Sound Power50 dB + 44 dB = 51 dB Logarithmic Addition of DecibelsHuman Ear Sound Perception Rating MethodsHuman Ear Response Loudness Contours Single-Number Rating Methods Response to TonesSingle-Number Rating Methods Sound Perception and Rating Methods C WeightingWeighting 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 Source-Path-Receiver Analysis Acoustical AnalysisSource-Path-Receiver Model Airborne Typical Sound PathsExample of Multiple Sound Paths Examples of a Single Sound PathIdentifying Sound Sources and Paths Sound-Path Modeling Modeling Sound PathsSupply Algorithms for Sound-Path Modeling Computerized Analysis Tools Terms Used in Sound-Path Modeling Attenuation and RegenerationSound Transmission Insertion loss IL Noise reduction NR Transmission loss TL Absorption Reflected Sound Receiver Sound Correction Equipment Sound Rating Equipment Sound RatingFields of Measurement Free FieldDistance Correction in a Free Field = L p1 20 logLot Near Field Reverberant Field Semireverberant Field Hvac Equipment Sound Rating Rating Hvac EquipmentReverberant-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-Period One ReviewNoise criteria NC Room criteria RC Review-Period TwoReview-Period Three Review-Period Four Review Questions for Period QuizOctave-band frequency, Hz Answers Glossary Glossary Room effect See receiver room correction Glossary Trane