arrow_back_ios

Main Menu

See All Acoustic End-of-Line Test Systems See All DAQ and instruments See All Electroacoustics See All Software See All Transducers See All Vibration Testing Equipment See All Academy See All Resource Center See All Applications See All Industries See All Insights See All Services See All Support See All Our Business See All Our History See All Our Sustainability Commitment See All Global Presence
arrow_back_ios

Main Menu

See All Actuators See All Combustion Engines See All Durability See All eDrive See All Production Testing Sensors See All Transmission & Gearboxes See All Turbo Charger See All DAQ Systems See All High Precision and Calibration Systems See All Industrial electronics See All Power Analyser See All S&V Hand-held devices See All S&V Signal conditioner See All Test Solutions See All DAQ Software See All Drivers & API See All nCode - Durability and Fatigue Analysis See All ReliaSoft - Reliability Analysis and Management See All Test Data Management See All Utility See All Vibration Control See All Acoustic See All Current / voltage See All Displacement See All Load Cells See All Pressure See All Strain Gauges See All Torque See All Vibration See All LDS Shaker Systems See All Power Amplifiers See All Vibration Controllers See All Accessories for Vibration Testing Equipment See All Training Courses See All Whitepapers See All Acoustics See All Asset & Process Monitoring See All Custom Sensors See All Data Acquisition & Analysis See All Durability & Fatigue See All Electric Power Testing See All NVH See All Reliability See All Smart Sensors See All Vibration See All Weighing See All Automotive & Ground Transportation See All Calibration See All Installation, Maintenance & Repair See All Support Brüel & Kjær See All Release Notes See All Compliance See All Our People
arrow_back_ios

Main Menu

See All CANHEAD See All GenHS See All LAN-XI See All MGCplus See All Optical Interrogators See All QuantumX See All SomatXR See All Accessories See All Accessories See All BK Connect / Pulse See All API See All Microphone Sets See All Microphone Cartridges See All Acoustic Calibrators See All Special Microphones See All Microphone Pre-amplifiers See All Sound Sources See All Accessories for acoustic transducers See All Experimental testing See All Transducer Manufacturing (OEM) See All Accessories See All Non-rotating (calibration) See All Rotating See All CCLD (IEPE) accelerometers See All Charge Accelerometers See All Impulse hammers / impedance heads See All Cables See All Accessories See All Electroacoustics See All Noise Source Identification See All Environmental Noise See All Sound Power and Sound Pressure See All Noise Certification See All Industrial Process Control See All Structural Health Monitoring See All Electrical Devices Testing See All Electrical Systems Testing See All Grid Testing See All High-Voltage Testing See All Vibration Testing with Electrodynamic Shakers See All Structural Dynamics See All Machine Analysis and Diagnostics See All Calibration Services for Transducers See All Calibration Services for Handheld Instruments See All Calibration Services for Instruments & DAQ See All On-Site Calibration See All Resources See All Software License Management

Transmission loss

Transmission loss measurements are used for comparisons of the acoustic attenuation of different materials, in analytical models used in the design of materials and components, and for verification of materials before they are turned into components.

Road surface absorption measurement

Affixed directly to the road surface, the system measures the absorption coefficient of the asphalt mixture non-destructively. The system uses a two-microphone, transfer-function method, to measure simultaneously at all frequencies.

With growing focus on noise control issues, the effect of materials in construction and as insulation makes a huge difference to the acoustic experience – the use of special materials can, for example, transform a space, keep vehicles within legal exterior noise limits, or create a noise-free environment. Acoustic material testing is the process for determining the acoustic characteristics of materials in terms of absorption, reflection, impedance, admittance and transmission loss, and is becoming increasingly relevant to engineers, designers and manufacturers from a broad range of industries. 

The effect of materials in construction and as insulation makes a huge difference in the acoustic experience. In offices and classrooms, the use of special materials can transform a space and with it the activities inside. In some applications – such as aircraft engines – they are what keep the vehicle within legal exterior noise limits. In others, like wind tunnels and anechoic chambers, acoustic materials are essential components in creating a noise-free, uniform test environment.

Creating an acoustic environment

To create a specific acoustic environment, it is necessary to understand the acoustic performance of the materials used. Testing materials for their acoustic characteristics lets architects, designers and engineers understand the contributions they can make to the overall sound, in terms of absorption, reflection, impedance, admittance; including transmission loss. Repeatability and precision are the keys to effective material testing – and data must be exportable to update predictive models.

 

Mitigating unwanted sound

To remove unwanted noise, one needs to match an acoustic material to the specific characteristics of the sound. But selecting the right material for the job is challenging. Certain materials alter some sound components, such as high frequencies, more than others do. Also, the selected material must create the desired acoustic effect in concert with other materials in the structure. What’s more, the structure’s final shape can affect the acoustic performance of its materials, such as the nacelle liners in an aircraft engine. A precise understanding of the material’s acoustic characteristics, such as its performance at certain frequencies, is essential – both before and after structural integration.

Acoustic material testing is the process for determining the acoustic characteristics of materials in terms of absorption, reflection, impedance, admittance and transmission loss. Growing focus on noise control issues, combined with the emergence of sound quality in product design, makes acoustic material testing increasingly relevant to engineers, designers and manufacturers in a broad range of industries. For example, improving cabin acoustic comfort by providing optimal acoustic material performance against weight and volume is one of today’s challenges in the ground transportation and aerospace industries. Similarly, protection against noise in dwellings and at the workplace most often requires the appropriate selection of noise-reducing treatments.

A range of standards covers acoustic material testing, prescribing well-defined acoustical conditions and special instrumentation to ensure accuracy and repeatability. Our complete acoustic material testing systems make measurements on small samples according to ISO 10534-2, ASTM E1050-12 and ASTM E2611-17 international standards.

System Suggestion

Acoustic material testing system overview

PULSE Acoustic Material Testing in a Tube Type 7758 is software for determining the acoustic properties of noise control materials, whether used to absorb airborne sound or to reduce airborne sound transmission. It works in conjunction with Brüel & Kjær’s Impedance Tube Kits, Transmission Loss Tube Kit and any other custom measurement tube. 

Increasingly stringent aerospace environmental regulations are demanding improvements in liner attenuation, which is driving ever-improved impedances in installed acoustic liners. As a result, fully bonded panels must now be assessed for their true effective acoustic behaviour in their final condition. These measurements are superseding the traditional geometric and DC load flow methods.

 

System Suggestion

Impedance measurements system overview

The Portable Impedance Meter System is a lightweight, compact, robust and user-friendly system suitable for both research and production quality control impedance measurements up to 150 dB SPL. Based on the two-microphone transfer function test method, it includes PULSE Material Testing and Impedance Meter software, a LAN-XI generator module as the input module for the two microphones, and a generator for the impedance meter sound source and for control of the environmental parameters. A power amplifier, conveniently housed in a double LAN-XI casing, provides the amplification of the generator signal. A portable impedance tube, accessories and a carrying case that holds all the elements of the system, are also included.