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ClimateMaster Engineering Sound Lab

ClimateMaster Engineering Sound Lab. By Wes Wostal. How The New Sound Lab Evolved. Importance of sound Great products... No real way to design for sound Easy justification. Design Goals. Must be in house Test capability to 50 & 60 Hz Construction of reverberant room

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ClimateMaster Engineering Sound Lab

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  1. ClimateMaster Engineering Sound Lab By Wes Wostal

  2. How The New Sound Lab Evolved • Importance of sound • Great products... No real way to design for sound • Easy justification

  3. Design Goals • Must be in house • Test capability to 50 & 60 Hz • Construction of reverberant room • Construction of “ducted discharge” room • National Instruments LabVIEW • ISO 3741 • NAVLAP certified • Capable 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. Wave length: λ = c/f Wave length at 60 Hz = 18.8 ft Wave length at 125 Hz = 9.0 ft ClimateMaster sound lab internal dimensions: 31’L x 24’ W x 19’ T c (air) = 1128 ft/sec f = frequency (Hz) Test Capability Down to 50 & 60 Hz

  6. Reverberant Room Size Requirements Chamber Volume by ISO 3741

  7. ClimateMaster Reverberant Room Volume 400 m³ = 14136 ft³

  8. Construction Reverberant Room • Isolated slab • 4” thick inner steel walls • 8” thick outer sand filled concrete block wall • 1’ wide air gap • 2’ effective wall thickness • Sound attenuators for return and supply air

  9. Construction “Ducted Discharge” Room • 4” thick perforated steel walls • Single sound attenuator for return and supply Air

  10. National Instruments LabVIEW • Great history with LabVIEW • LabVIEW for sound data measurement • LabVIEW for room conditioning • 25 tons of air side conditioning • 30 tons of water side conditioning • 10,000 CFM variable frequency drive air handler • 36” double walled duct

  11. ISO 3741 • Acoustics - Determination of sound power levels of noise sources using sound pressure - Precision methods for reverberation rooms • Specifies 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

  12. NAVLAP Certified • NationalVoluntaryLaboratoryAccreditationProgram • Administered through NIST

  13. Capable Of Taking Us Into The Future • ClimateMaster products quieter by design • Interior sound levels < NC20

  14. From ClimateMaster to Customer • Sound testing as part of development • ARI 260 and 350 standards • Product sound data • NC • ClimateMaster Sound Analyzer

  15. ARI 260 Sound Rating of Ducted Air Moving and Conditioning Equipment Adopted in 2000 Revised in 2001

  16. What is ARI 260? • Sound rating standard for ducted air moving and conditioning equipment • Establishes a method of sound rating indoor a/c equipment • Covers air source-ARI 240, & 340; water source-ISO 13256; fan Coil-ARI 440; central station ARI 430 • Provides for standard published data

  17. Why ARI 260? • Previously no valid sound rating standard for wshp’s • Every manufacturer used different testing procedure • Sound rating comparisons between manufacturers were impossible

  18. 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.

  19. Sound Power Vs Pressure

  20. 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.

  21. Definitions Continued • Frequency or Hz - Cycles per second • Frequency Spectrum - Audible range of frequency 20 - 20000 Hz for humans • dB - Decibel unit of measure expressing a log ratio of two quantities. 3-5dB barely perceptible. 10dB is perceived as twice as loud

  22. 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 8000 • 1/3 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.

  23. What is Sound • A disturbance that propagates in an elastic medium (air) • Created by a transference of mechanical energy to the medium • Generally associated with the auditory sensation created by the disturbance in the medium

  24. What is Noise? • Unwanted Sound: A waste byproduct of mechanical, electrical, and fluid processes • Noise consists of energy at frequencies that are representative of the mechanical processes that create the sound

  25. Frequency Spectrum

  26. Typical Sound Pressure Levels

  27. Why is Measuring Sound So Difficult? • Measuring sound is more difficult than pressure or temperature • Requires detailed analysis of distinct frequencies • Human ears sense sound from 20Hz-20KHz • ClimateMaster Sound Analyzer accommodates a wide range 50Hz-11KHz • More than 10,000 data points to analyze per test • We have the solution!!

  28. Product Sound Data • Product Sound Test Method • Set room conditions • Run ambient / background test • Run RSS (reference sound source) • Run test unit

  29. Product Sound Data • Sound Data Collected • Sound pressure of ambient • Sound pressure of RSS • Sound pressure (Lp) of unit

  30. Product Sound Data • 1/3 octave sound power calculations • Sound power: Lw = Lp + (Lwp - Lpr) • Lp = Sound pressure of unit • Lwp = Sound power of the RSS • Lpr = Sound pressure of the RSS

  31. Product Sound Data • 1/1 octave sound power calculations • Example 100Hz, 125Hz, and 160Hz • Lwo = 10log10[Σ10(Lw(n)/10)] • Lwo = 125Hz octave band sound power • Lw(n) = sound power of each 1/3 octave • Lwo = 1/1 octave sound power = published data

  32. A & C Weighted Sound Power Level • A Weighted Sound Power Level • Range of 700 - 4000 Hz • Noise in occupational environment • Best with sources of similar range • C Weighted Sound Power Level • Range of 50 - 5kHz • Wide range noise in occupational environment • Best with sources of wide range like music etc.

  33. 1/1 Octave Hz A-Weight Adder

  34. ARI 260 Test Setup Options • Ducted discharge • Ducted inlet • Free inlet and casing radiated • Casing radiated • Free inlet

  35. Ducted Discharge

  36. Ducted Inlet

  37. Free Inlet & Casing Radiated

  38. Casing Radiated

  39. Free Inlet

  40. GRH/V 030 ARI 260 Free Inlet & Case Radiated Data

  41. GRH/V 030 ARI 260 Ducted Discharge Data

  42. NC (Noise Criterion Curves) • Provide a coloration curve of response that represents the ear’s sensitivity to sound • Curve range is 63 - 8000 Hz and on an octave band sound pressure scale • Often used in building design • Source sound pressure level measured at each octave band must be below the specified NC curve to meet NC rating

  43. Typical NC Curves

  44. NC50 Unit NC Rating

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