Trane TRG-TRC007-EN manual Equation for Sound Power, Equation for Sound Pressure

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period one

Fundamentals of Sound

notes

Equation for Sound Power

	Lw	= 10 log10	sound power, W
			10-12	W

Figure 15

When a reference value is established and placed in the denominator of the ratio, the dB can be calculated for any value entered into the numerator.

The reference value used for calculating sound-power level is 1 picowatt (pW), or 10-12watts. Therefore, sound-power level (Lw) in dB is calculated using the following equation:

LW = 10 log10

sound power, watts

-------------------------------------------------------

10-12watts

Equation for Sound Pressure

	Lp	= 20 log10	sound pressure, mPa
			20 mPa

Figure 16

The reference value used for calculating sound-pressure level is 20 micropascals (µPa), or 2 ×10-5Pa. Therefore, sound-pressure level (Lp) in dB, is calculated using the following equation:

TRG-TRC007-EN

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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