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ClimateMaster Engineering Sound Lab

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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 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 Test Capability Down to 50 & 60 Hz
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: ’L x 24’ W x 19’ T c (air) = 1128 ft/sec f = frequency (Hz)

6 Reverberant Room Size Requirements Chamber Volume by ISO 3741

7 ClimateMaster Reverberant Room Volume
= 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




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


14 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



17 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

18 NAVLAP Certified National Voluntary Laboratory Accreditation Program
Administered through NIST

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

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

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

22 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

23 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

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.

25 Sound Power Vs Pressure

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 second Frequency Spectrum - Audible range of frequency 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

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 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.

29 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

30 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

31 Frequency Spectrum

32 Typical Sound Pressure Levels

33 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!!

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

35 Product Sound Data Sound Data Collected Sound pressure of ambient
Sound pressure of RSS Sound pressure (Lp) of unit

36 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

37 Product Sound Data Lwo = 1/1 octave sound power = published 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

38 A & C Weighted Sound Power Level
A Weighted Sound Power Level Range of Hz Noise in occupational environment Best with sources of similar range C Weighted Sound Power Level Range of kHz Wide range noise in occupational environment Best with sources of wide range like music etc.

39 1/1 Octave Hz A-Weight Adder

40 ARI 260 Test Setup Options Ducted discharge Ducted inlet
Free inlet and casing radiated Casing radiated Free inlet

41 Ducted Discharge

42 Ducted Inlet

43 Free Inlet & Casing Radiated

44 Casing Radiated

45 Free Inlet

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

47 GRH/V 030 ARI 260 Ducted Discharge Data

48 NC (Noise Criterion Curves)
Provide a coloration curve of response that represents the ear’s sensitivity to sound Curve range is 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

49 Typical NC Curves

50 Unit NC Rating NC50

51 ClimateMaster Sound Analyzer


53 Important Notes 63 Hz is difficult to test
125 Hz is most problematic octave

54 About Comparison Must be ‘apples to apples’-Look for ARI 260 conformance Look 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 affects Sound power can be used to predict sound pressure in a specified room ARI 260 and 350 are THE ONLY sound rating standards Comparisons valid using ARI 260 only Use the ClimateMaster Sound Analyzer

56 Thank You

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