Presentation on theme: "ClimateMaster Engineering Sound Lab"— Presentation transcript:
1 ClimateMaster Engineering Sound Lab By Wes Wostal
2 How The New Sound Lab Evolved Importance of soundGreat products... No real way to design for soundEasy justification
3 Design Goals Must be in house Test capability to 50 & 60 Hz Construction of reverberant roomConstruction of “ducted discharge” roomNational Instruments LabVIEWISO 3741NAVLAP certifiedCapable of taking us into the future
4 In House Lab Outside sound testing is expensive Outside testing offers little to no design change opportunity
5 Test Capability Down to 50 & 60 Hz Wave length: λ = c/fWave length at 60 Hz = 18.8 ftWave length at 125 Hz = 9.0 ftClimateMaster sound lab internal dimensions: ’L x 24’ W x 19’ Tc (air) = 1128 ft/secf = frequency (Hz)
6 Reverberant Room Size Requirements Chamber Volume by ISO 3741
14 National Instruments LabVIEW Great history with LabVIEWLabVIEW for sound data measurementLabVIEW for room conditioning25 tons of air side conditioning30 tons of water side conditioning10,000 CFM variable frequency drive air handler36” double walled duct
17 ISO 3741Acoustics - Determination of sound power levels of noise sources using sound pressure - Precision methods for reverberation roomsSpecifies room requirements, source location, general rules for operating conditions, instrumentation and techniques for obtaining sound pressure levels from which sound power levels are calculated with grade 1 accuracy
18 NAVLAP Certified National Voluntary Laboratory Accreditation Program Administered through NIST
19 Capable Of Taking Us Into The Future ClimateMaster products quieter by designInterior sound levels < NC20
20 From ClimateMaster to Customer Sound testing as part of developmentARI 260 and 350 standardsProduct sound dataNCClimateMaster Sound Analyzer
21 Sound Rating of Ducted Air Moving and Conditioning Equipment ARI 260Sound Rating of Ducted Air Moving and Conditioning EquipmentAdopted in 2000Revised in 2001
22 What is ARI 260?Sound rating standard for ducted air moving and conditioning equipmentEstablishes a method of sound rating indoor a/c equipmentCovers air source-ARI 240, & 340; water source-ISO 13256; fan Coil-ARI 440; central station ARI 430Provides for standard published data
23 Why ARI 260? Previously no valid sound rating standard for wshp’s Every manufacturer used different testing procedureSound rating comparisons between manufacturers were impossible
24 Important Definitions Sound Power: W [watt], is a fundamental property of a sound source, the amount of acoustic energy radiated into the environment. denoted by ‘Lw’Sound Pressure: is the expression of the acoustic power in the environment. denoted by ‘Lp’Reference Sound Source: A portable, aerodynamic sound source that produces a known stable broad band sound power output.
26 Definitions Continued Comparison Method: A method of determining sound power level of a source under test in a reverberation room by comparing the average sound pressure level of that source to the average sound pressure level of a reference sound source of know sound power level output. the difference in sound power level is equal to the difference in sound pressure level when the conditions in the room are the same for both sets of measurements.
27 Definitions Continued Frequency or Hz - Cycles per secondFrequency Spectrum - Audible range of frequency Hz for humansdB - Decibel unit of measure expressing a log ratio of two quantities. 3-5dB barely perceptible. 10dB is perceived as twice as loud
28 Definitions Continued Octave Band: a band of sound covering a range of frequencies such that the highest is twice the lowest. octave band frequencies are: 63; 125; 250; 500; 1000; 2000; 4000; and 80001/3 Octave Band: A band of sound covering a range of frequencies such that the highest frequency is the cube root of two times the lowest. 1/3 octave band frequencies for the 125 Hz octave band are: 100; 125; and 160.
29 What is Sound A disturbance that propagates in an elastic medium (air) Created by a transference of mechanical energy to the mediumGenerally associated with the auditory sensation created by the disturbance in the medium
30 What is Noise?Unwanted Sound: A waste byproduct of mechanical, electrical, and fluid processesNoise consists of energy at frequencies that are representative of the mechanical processes that create the sound
33 Why is Measuring Sound So Difficult? Measuring sound is more difficult than pressure or temperatureRequires detailed analysis of distinct frequenciesHuman ears sense sound from 20Hz-20KHzClimateMaster Sound Analyzer accommodates a wide range 50Hz-11KHzMore than 10,000 data points to analyze per testWe have the solution!!
34 Product Sound Data Product Sound Test Method Set room conditions Run ambient / background testRun RSS (reference sound source)Run test unit
35 Product Sound Data Sound Data Collected Sound pressure of ambient Sound pressure of RSSSound pressure (Lp) of unit
36 Product Sound Data 1/3 octave sound power calculations Sound power: Lw = Lp + (Lwp - Lpr)Lp = Sound pressure of unitLwp = Sound power of the RSSLpr = Sound pressure of the RSS
37 Product Sound Data Lwo = 1/1 octave sound power = published data 1/1 octave sound power calculationsExample 100Hz, 125Hz, and 160HzLwo = 10log10[Σ10(Lw(n)/10)]Lwo = 125Hz octave band sound powerLw(n) = sound power of each 1/3 octaveLwo = 1/1 octave sound power = published data
38 A & C Weighted Sound Power Level A Weighted Sound Power LevelRange of HzNoise in occupational environmentBest with sources of similar rangeC Weighted Sound Power LevelRange of kHzWide range noise in occupational environmentBest with sources of wide range like music etc.
48 NC (Noise Criterion Curves) Provide a coloration curve of response that represents the ear’s sensitivity to soundCurve range is Hz and on an octave band sound pressure scaleOften used in building designSource sound pressure level measured at each octave band must be below the specified NC curve to meet NC rating
53 Important Notes 63 Hz is difficult to test 125 Hz is most problematic octave
54 About ComparisonMust be ‘apples to apples’-Look for ARI 260 conformanceLook for weighting ‘A’ versus ‘C’No ARI No comparison
55 Things to Remember Sound power is pure source energy Sound pressure is source with room affectsSound power can be used to predict sound pressure in a specified roomARI 260 and 350 are THE ONLY sound rating standardsComparisons valid using ARI 260 onlyUse the ClimateMaster Sound Analyzer