Automotive Acoustics

Silence through Science
Impedance Tube for Sound Absorption and
Sound Transmission Loss Measurements
Alfa Acoustic Impedance tube is designed to
measure sound absorption coefficient as per test
standards ASTM E1050 / ISO 10534-2. The
measurement software is based on the Transfer
Function Method. The Transfer Function method
separates the incident and reflected energy from
the measured transfer function, and then
estimates the acoustic properties of the test
sample. The sound transmission loss module is as
per ASTM E2611. Alfa Acoustics offers complete
set of Impedance Tube system, which includes: the
tubes, microphones; Data Acquisition hardware
and measurement software.
Alfa Acoustics Impedance Tubes
Two Microphone Impedance Tube
Four Microphone Transmission Loss Tube
Power Amplifier and Data Acquisition System Screen Shot of a Measurement Software
Technical Specifications
Internal Diameter (mm)
Sound Absorption Standard
Sound Transmission
Loss Standard
Frequency Range (Hz)
Microphones
Loudspeaker
Pressure Pump
Contact:
Dr. Paresh Shravage
info@alfaacoustics.com | alfaacoustics@gmail.com
+91 9423208575 / +91 9975082075
Plot No.-5, Swami Vivekanand Soc. Walhekar Wadi Rd, Chinchwad, Pune, India – 411033
www.alfaacoustics.com
Impedance Tube Set
Tube Large Small Medium
100 29 45
ASTM E1050 / ISO 10534-2
ASTM E2611
100-1600 700-6300 100-4500
¼”, Pressure Field – 4 Nos
4" in diameter, 15 Watts, 6 Ohm
Salient Features
Designed as per International
and National Standards
Low Cost and Lightweight Solution
Quick and Simple to use
Measurement of Surface Properties
like Reflection Coefficient, Surface
Impedance
Direct data export to excel sheet

Portable Pavement Absorption Tube
Alfa Acoustic Impedance tube is designed to measure sound
absorption coefficient of road surfaces as per standards ISO
13472-2 which are regulated by standards ISO 10844 / IS
3028. As per the standard ISO 13472-2, this tube is vertically
mounted on the road surface to measure sound absorption
coefficient at normal incidence with the help of specially
designed base structure. This special design eliminates the
need of drilling a sample in the road surface. Alfa Acoustics
offers complete set of Impedance Tube system, which
includes: the tube, microphones; Data Acquisition
hardware and measurement software.
Impedance tube with power Amplifier
and Data Acquisition System
Screen Shot of a Measurement Software
Portable Pavement Absorption Tube
Tube
Internal Diameter (mm)
Standard
Frequency Range (Hz)
Large
100
ISO 13472-2
200 – 1800
Contact:
Dr. Paresh Shravage
+91 9423208575 / +91 9975082075
¼”, Pressure FieldMicrophones
Salient Features
Designed as per International and National
Standards
Low Cost and Lightweight Solution
Quick and Simple to use
Measurement of Sound Absorption Coefficient
Measurement of Surface Properties like Reflection
Coefficient, Surface Impedance
User friendly software Interface

Acoustic Cabin for Insertion Loss Measurements
Alfa Acoustics - Acoustic cabin is a simple test rig used to measure Insertion Loss (IL) of sound package
treatments. This test rig resembles with a scaled down model of a reverberation chamber – which acts as a
source chamber with noise source of 120 dB and an anechoic chamber – which acts as a reception chamber.
The lower and upper part of the chamber are separated by a thick sample mounting plate on which different
types of test samples can be mounted easily. This Acoustic cabin is a perfect facility for measurements of acoustic
treatments, cavity fillers, grommets, etc. Acoustic cabin can also be customized as per customer test
requirements.
Alfa Acoustics offers a complete set-up of Acoustic cabin along with microphones, Data Acquisition hardware
and measurement software.
Acoustic Cabin Source Chamber
Reception Chamber Screen Shot of a Measurement Software
Typical Result of an Acoustic Treatment
Acoustic Cabin
Dimensions
Sample Size
Sound Source
Frequency Range
Standards
Applications
0.9 x 0.9 x 1.8 m (L x B x H)
Min - 350 x 350 mm & Max- 700 x 700 mm
9 Speakers connected to give Sound Pressure
Level up to 120 dB
500 – 10000 Hz
SAE J2846 (Cavity Fillers), Daewoo-5412
Insertion loss measurement of Acoustic Baffles,
Dash Insulator, Floor Carpet, Grommets, etc.
Salient Features
Designed as per OEM Test
Practices
Low Cost and Perfect for
Quality Control
Contact:
Dr. Paresh Shravage
+91 9423208575 / +91 9975082075

Acoustic Material Database for Sound
Package Materials
Alfa Acoustics - Acoustic material database is an unique tool for storing acoustic material properties for future
usage. This software stores all physical, mechanical and acoustic properties of acoustic materials along with its
picture.
The data stored in this software can be easily retrieved, compared and exported for later use in advanced
softwares for simulated purpose.
The software can store following parameters also known as Biot Parameters:
Contact:
Dr. Paresh Shravage
+91 9423208575 / +91 9975082075
Porosity Airflow Resistivity Tortuosity Viscous Characteristic Length (VCL)
Thermal Characteristic Length (TCL) Density Young’s Modulus Poisson Ratio
Loss Factor Sound Absorption Coefficient (SAC) Sound Transmission Loss (STL)
Surface Impedance Reflection Coefficient
*Along with GSM and thickness of the materials
Vehicle Level NVH Simulation in FEA, SEA Software
Input Parameters to Acoustic Database

Porosity Rig for Acoustic Materials
Alfa Acoustics Porosity test rig is based on Boyle’s law. The principle is to reduce the
volume of an enclosure where a material sample is placed. While doing so, the
pressure will increase in the enclosure compared to the atmospheric pressure. Off
course this increase of pressure depends on the volume of the enclosure and the
volume accessible to the air inside the porous medium. By measuring the
pressure increase it is possible to determine the open porosity of the material.
Porosity is one of the important parameter for sound absorbing acoustic
materials (Biot Parameter). The sound absorption coefficient is mostly governed
by porosity of sound absorbing materials.
Field of Application
Quality Control of Acoustic Materials – Highly useful for quality control of
acoustic materials during manufacturing process.
Simulation – Important parameter for simulation in softwares like VAOne, Virtual
Lab, SEAM, etc.
Test Materials
Open-cell foams
Glass wool, Mineral wool
Cellular, Granular materials, fills
Felts, Fibers
Concretes, Open Porous Asphalts
Porosity Test Rig
Overall Dimensions
Sample Diameter
Sample Thickness
Airflow Source
0.45 x 0.55 x 1.2 m (L x B x H)
100 mm
5-100 mm
Pneumatic Piston
0.3 - 0.99 [-]Airflow Resistivity Range
Applications Foams, Fibers, Felts, Natural
Sound Absorbing materials, etc.
Contact:
Dr. Paresh Shravage
+91 9423208575 / +91 9975082075

Airflow Resistivity Test Rig for Acoustic Materials
Alfa Acoustics - Airflow Resistivity test rig is designed as per ASTM
C522/ISO 9053 standards. This method requires simultaneous
measurement of air pressure difference across the open cell acoustic
sample with respect to air volume velocity. The test rig consists of a
specially designed transparent sample holder for holding acoustic test
samples. A pressure pump is used to suck the air through the sample
and the rate of airflow through the sample is controlled by a pressure
regulator.
Airflow Resistivity Rig
Overall Dimensions
Sample Diameter
Airflow Source
Standards
Airflow Resistivity
Range
Applications
0.45 x 0.55 x 1.2 m (L x B x H)
100 mm
Pressure Pump
ASTM C522 / ISO 9053
4
500 - 1000000 Ns/m
Dash Insulator, Headliner, Hood Insulator, Trim Parts,
Resis ve Scrims
Contact:
Dr. Paresh Shravage
+91 9423208575 / +91 9975082075
Quality Control of Acoustic Materials – Highly useful for quality
control of acoustic materials during manufacturing process.
Simulation – Important parameter for simulation in softwares like
VAOne, Virtual Lab, SEAM, etc.
Test Materials
Open-cell Foams Glass wool, Mineral wool Granulates, Fills Felts, Fibers,
Perforated Plates Concretes, Open Porous Asphalts Metal Fiber Sound Absorbers

Sound Package Materials - Automotive
Inverse Characterization for Intrinsic Physical Parameters
Tortuosity
Viscous Characteristic Length
Thermal Characteristic Length
Sound Package Materials-Automotive
Effect of Intrinsic Parameters on Sound Absorption and Sound Transmission Loss
Effect of Porosity Effect of Airflow Resistivity Effect of Tortuosity Effect of Viscous Length
Simulation of Cotton Shoddy - Sound Absorption Simulation of Hood Insulator- Sound Absorption Simulation of Vehicle Carpet-Transmission Loss

Contact:
Dr. Paresh Shravage
+91 9423208575 / +91 9975082075
Acoustic Materials – Simulation and Measurement Systems
Sound Absorption and Transmission Loss
Two and Four Microphone
Impedance Tube as per ISO 10534-
2 / ASTM E1050 / ASTM E2611
Small Reverberation Chamber for
diffuse field sound absorption
measurements as per SAE J2883
Airflow
Resistivity Rig
Porosity Rig
Tortuosity
Acoustic Performance of Cavity Fillers and Grommets - Acoustic Cabin
Sound Insertion Loss Measurement of Sound Package Treatments
SAE J2846 – Laboratory Measurement of the Acoustical Performance of Body Cavity Fillers
Grommet and Sealing system Testing as per PSA B65 4250 / Renault D45 2019
Acoustic Cavity Fillers Testing –Small Cabin
Test as per SAE J2846
Acoustic Transparency Testing –Small Cabin
Customized Test Facility and Simulation Softwares -
Alfa Acoustics can help in design and development of in-house test facility and customized softwares for
its customers which can predict acoustic performance

α - Sim: Simulation Software for Sound
Absorption and Sound Transmission Loss
Alfa Acoustics - Sim is a simulation software for predictingα
acoustic performance of acoustic materials used in
Automotive or Architectural Acoustics. It is a simple user
friendly software which is based upon mathematical modeling
of acoustic materials and uses physical parameters like Airflow
resistivity – single parameter or with other number of
parameters like porosity, tortuosity and characteristics
lengths. It can also take fiber denier as an input to predict
sound absorption and sound transmission loss of fibrous
materials like Glass wool or Mineral wool or Polyester felts.
Foam - open cell, metallic, chipped foam, etc.
Fiber - glass wool, glass fiber, felt, cotton, fabrics, etc.
Resistive Screens, Fabrics, Perforated Plates, Films, Foils, etc.
Viscoelastic and sound deadeners
Useful for Manufacturers, Suppliers, Architects, Engineers
Low Cost and Easy to use
Gives NRC and STC values within seconds
Prediction for Normal as well as Random Incidence
Useful for In-house quality control
Uses measured flow resistivity or fiber denier as an input
Predicts effects of Scrim, foils and films also
Possible to predict acoustic performance for different thicknesses without manufacturing actual material
Saves time and Cost
Salient Features
Contact:
Dr. Paresh Shravage
+91 9423208575 / +91 9975082075

Contact:
Dr. Paresh Shravage
+91 9423208575 / +91 9975082075
α - Inverse : Physical Parameters of Acoustic
Materials
α - Inverse is a simple and powerful tool to get intrinsic
parameters of acoustic materials. Acoustic performance of
sound absorbing porous materials is governed by its intrinsic
parameters (Biot Parameters). These parameters are very
important in material - component - product level simulation
process.
α - Inverse provides a simplest and easiest way to get these
Biot parameters with desired accuracy. It works with ASTM
E1050 / ASTM E2611 sound absorption and transmission loss
measurement systems and only requires porosity as
measured parameter.
Tortuosity
Viscous Characteristic Length (VCL)
Thermal Characteristic Length (TCL)
Computed Properties
Simulation – During simulation in softwares like -sim,α
NOVA, VAOne, Virtual Lab, SEAM, etc.
Foam - open cell, metallic, chipped foam, etc.
Fiber - glass wool, glass ﬁber, felt, cotton,
fabrics, etc.
Materials to be Tested
Errors are below than 5% compared to Measurement
Quick and Simple
Saves huge cost and time
Advantages
Comparison of Experimental and
Inverted Parameters
Parameters Exp. Inverse
Porosity
Tortuosity
VCL
TCL
5359
0.98
1.1
100
240
6036
0.98
1.11
125
295
Technical Validation of - Inverseα

Sound Package Materials –
Design, Simulation and Testing
Sound Absorption Testing
It is defined as the ratio of the sound energy reflected by a surface to the sound energy incident upon that surface
Test Components - Headliners, Luggage mat, Seats, Engine Encapsulation, Floor Carpets, Hood insulation, Wheel Liners,
Package Trays etc.
Test Standards
ISO 10534-2 Determination of sound absorption coefficient and impedance in impedance tube-Transfer function method
ISO 354 Measurement of a sound absorption coefficient in a reverberation room
ASTM C423 Standard test method for sound absorption and sound absorption coefficients by reverberation room method
SAE J2883 Laboratory Measurement of random incidence sound absorption tests using a small reverberation room
PU Foam with Film Recycled Foam
Melamine Foam
with Scrim
Melamine Foam
Impedance Tube
Small Reverberation
Chamber
Sound Absorption Measured in an
Impedance Tube
Sound Absorption Measured in a
Small Reverberation Chamber -
Alpha Cabin
Sound Transmission Loss Testing -
It is defined as the ratio of sound power incident on a material to the sound power transmitted through the material.
Test Components - Dash Insulators, Hood Insulator, Floor Carpet, Windshield etc.
Test Standards -
SAE J1400 - Laboratory measurement of airborne sound transmission loss
ISO 10140-2/ ASTM E90- Measurement of sound insulation in building and building elements
ASTM E2249-2 - Standard Test Method for Laboratory Measurement of Airborne Sound Transmission Loss of
Building Partitions using Sound Intensity
Composite Foam PU Foam with EPDM
EPDM PU Foam with Film
and EPDM
Impedance Tube
Two Reverberation Chamber Suite
Sound Transmission Loss Measured
in an Impedance Tube
Sound Transmission Loss Measured
in a Reverberation Chamber Suite
NVH Testing for Acoustic Targets –
Consultancy for achieving absorption, insertion and transmission loss targets
Master report for effect of acoustics parameters on test targets
Design of acoustic treatments for meeting test targets

Contact:
Dr. Paresh Shravage
+91 9423208575 / +91 9975082075
Porosity Measurement by Porosity test rig
Airflow Resistivity Measurement by Flow resistivity rig based on ASTM C522/ISO 9053
Tortuosity and characteristic lengths by indirect method and Inverse characterization
Simulation of Multiple Thickness Materials
Simulation of Door Trims - Sound AbsorptionSimulation of Cotton Shoddy
Effect of Acoustic Leakage
Leakages play crucial role in transmission path at
mid/high frequencies
Leakages are due to pass-throughs, Boot liners,
Simulation of Dash- Sound Transmission LossSimulation of Vehicle Carpet-Transmission Loss
Oberst Bar Testing-Damping Loss Factor
Evaluation of damping loss factor of melt sheets, rubber sheets, etc.
Testing as per ASTM E756, SAE J1637, SAE J3130, Ford, GM standards
Customized Test Facility and Simulation Softwares -
Alfa Acoustics can help in design and development of in-house
test facility and customized softwares for its customers which
can predict acoustic performance
Sound Package Material Characterization and Simulation
Effect of Area on Sound Package
Porosity
Tortuosity
Macroscopic Characterization

Acoustics of Foams and Fibers
Sound Absorption Coefficient
It is defined as the ratio of the sound energy reflected by a surface to the sound energy incident upon that
surface.
Test Standards
ISO 10534 - Determination of sound absorption coefficient and impedance in impedance tube-Transfer
function method
ISO 354 - Measurement of a sound absorption coefficient in a reverberation room
ASTM C423 - Standard test method for sound absorption and sound absorption coefficients by reverberation
chamber method
Acoustic Material Characterization and Simulation
Porosity Measurement by Porosity test rig
Airflow Resistivity Measurement by Flow resistivity rig based on ASTM C522
Tortuosity and characteristics lengths by indirect method and Inverse characterization
Design and simulation of multilayer treatments for Genset and Industrial Applications
Effect of Films / Foils / Resistive layers with Foams/Fibers/Felts
Impedance Tube Simulation and Validation of PU Foam
Multilayer Sound Absorption Simulation Variation in Airflow Resistivity of Same
Density Foam
Simulation and Validation for multilayer
combination
PU Foam

Contact:
Dr. Paresh Shravage
+91 9423208575 / +91 9975082075
New Architectural Acoustics Trends
Sound Absorption Simulation-Multiple
Thickness
Airﬂow Resistivity Variation in
same density foam
Simulation and Validation
of PU Foam
Simulation and Validation for
Composite PU Foam
Impedance Tube ASTM
E1050 / ISO 10534-2
Simulation of Rockwool
Sound Absorption
Simulation and Validation for
Composite PU Foam
Sound Absorption-Same Density,
Same Thickness
Simulation of Polyester Felt
Sound Absorption
Simulation of Polyester Felt
Sound Transmission Loss
Porosity
Tortuosity
Macroscopic Characterization

Automotive Acoustics

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