ACUPRO Version 4
Measurement of Acoustical Properties of
Materials and Systems
Spectronics, Inc., Lexington, KY USA
www.spectronics.net
Tel.: 001-859-321-1843 Fax: 001-859-273-9793
Applications
ACUPRO Version 4
1. Measurement of absorption coefficient of materials
2. Measurement of transmission loss (TL)
Barrier materials
Mufflers and silencers
3. Determination of flow resistivity (using FOAM-X)
4. Microphone phase measurement
Sound intensity measurements
2
History of ACUPRO
ACUPRO Version 4
Spectronics ACUPRO ACUPRO ACUPRO ACUPRO
founded launched Version 2 Version 3 Version 4
1988 1994 1998 2004 2007
3
Research Foundation
ACUPRO Version 4
1. Seybert, A.F. and Ross, D.F., Experimental Determination of Acoustic
Properties Using a Two-microphone Random Excitation Technique, J.
Acoust. Soc. Am., 61, 1362-1370 (1977)
2. Chung, J.Y. and Blaser, D.A., Transfer Function Method of Measuring
In-duct Acoustic Properties, II: Experiment, J. Acoust. Soc. Am, 68,
914-921 (1980)
3. Seybert, A.F., Two-sensor Methods for the Measurement of Sound
Intensity and Acoustic Properties in Ducts, J. Acoust. Soc. Am, 83,
2233-2239 (1988)
4. Tao, Z. and Seybert, A. F., A Review of Current Techniques for
Measuring Muffler Transmission Loss, Proceedings, SAE Noise and
Vibration Conference, Traverse City, paper 2003-01-1653 (2003)
4
Standards
ACUPRO Version 4
1. ISO 10534-2, Acoustics-Determination of sound absorption coefficient
and impedance in impedance tubes - Part 2: Transfer-function method
2. ASTM E1050-98, Standard Test Method for Impedance and
Absorption of Acoustical Material Using a Tube, Two Microphones and
a Digital Frequency Analysis System
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ACUPRO Hardware
ACUPRO Version 4
Exceeds ISO and ASTM design requirements
Thick-walled, highly damped materials reduce vibration
Precision machining insures plane wave sound field
Microphone mounting is secure and sealed
High output JBL compression driver
JBL 2426J
Driver
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Specifications
ACUPRO Version 4
Frequency range: 50 Hz 5700 Hz
Maximum SPL in tube: ~ 150 dB
Ambient noise in tube: < 30 dBA
Microphones: accepts standard inch
Tube inside diameter: 34.9 mm
Tube outside diameter: 41.3 mm
Maximum length of sample: 14 cm
Overall length: 1.20 m (with sample holder)
Total mass: 10.5 kg
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Software Features - General
ACUPRO Version 4
Runs under Windows OS
Reads text files from any analyzer
Graphics visualization of all results
Log window tracks history
Hard copy of graphical results
Soft copy of all data in text files
Access to ACUPRO manual
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Sound Absorption Measurement
ACUPRO Version 4
Sample holder
with rigid piston
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Software Features Absorption Measurement
ACUPRO Version 4
Corrects microphone amplitude and phase
Corrects for latent tube absorption
Determines the following properties
9 Sound absorption coefficient
9 Complex sound reflection coefficient
9 Complex surface impedance
9 Complex surface admittance
Outputs data for flow resistivity determination
(using FOAM-X by ESI Group)
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Material Characterization Module
ACUPRO Version 4
Correction for
microphone
amplitude and
phase response
Graphical
display
windows
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Example - Absorption Measurement
ACUPRO Version 4
1.0
0.8
Absorption Coefficient
0.6
0.4 Foam with cover
Foam without cover
0.2
0.0
0 1000 2000 3000 4000 5000
Frequency (Hz)
12
Measurement of Transmission Loss
ACUPRO Version 4
Optional TL tube
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Software Features TL Measurement
ACUPRO Version 4
Corrects microphone amplitude and phase
Determines transmission loss (TL) of
Barrier materials
Mufflers and silencers
Other material properties determined
9 Complex wave number
9 Complex material density
9 Complex sound speed in material
9 Complex characteristic impedance
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Transmission Loss Module
ACUPRO Version 4
Files for TL
calculation
Properties
determined
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Measured TL of Barrier Material
ACUPRO Version 4
50
45
40
35
30
TL (dB)
25
20
15
10
5
0
0 1000 2000 3000 4000 5000 6000
Frequency (Hz)
16
Measured TL of an Expansion Chamber Muffler
ACUPRO Version 4
20 cm
30
25
20
TL (dB)
15
10
0
0 500 1000 1500 2000 2500 3000
Frequency (Hz)
17
Questions?
Spectronics, Inc., Lexington, KY USA
www.spectronics.net
Tel: 001-859-321-1843 Fax: 001-859-273-9793
