Trane TRG-TRC007-EN manual Octave-Band Rating Method

Page 35

period two

Sound Perception and Rating Methods

notes

Octave-Band Rating Method

octave		center		equipment		sound pressure
				equipment		sound pressure
				sound power		in the space
band		frequency (Hz)		(dB ref 10-12W)		(dB ref 20 mPa)
1		63		103		63
2		125		104		52
3		250		100		45
4		500		101		38
5		1,000		98		31
6		2,000		93		24
7		4,000		88		16
8		8,000		85		10

Figure 32

Octave-Band Rating Method

A more useful method of rating sound level is to use the octave bands discussed earlier. While octave-band data is not as simple to interpret as a single-number rating, it provides much more information about the character of the sound.

Both sound-power levels and sound-pressure levels can be presented in octave-band format. When equipment sound data is provided in terms of sound-power level in each octave band, an “apples to apples” comparison can be made between various pieces of equipment. In addition, this sound- power data can be converted to sound-pressure levels when the details of the environment are known. This type of analysis will be discussed further in Period Three.

Sound-pressure levels in each octave band, whether predicted from sound- power data or measured in an existing environment, reveal much more about the character of sound than any of the single-number rating methods. It is important to note that any of the single-number ratings described in this section can be calculated from octave-band sound-pressure data. However, octave- band data cannot be derived from any of the single-number ratings.

28	TRG-TRC007-EN

Image 35

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 Response Sound Perception Rating MethodsHuman Ear 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