Measurement Microphones

National Instruments has announced that NI Alliance Partner G.R.A.S. Sound & Vibration, a leading producer of acoustic front-end products, now sells microphone kits for use with NI dynamic signal acquisition (DSA) hardware. NI offers several different microphone types, from array microphones to condenser microphones appropriate for class 1 sound-level measurements. Customers in a number of industries, including aerospace and defence, are already having success using these products for applications like acoustic holography, environmental noise, noise mapping and sound power.

“For more than 10 years G.R.A.S. and NI have worked together on joint projects, and there has always been a great collaboration between our companies,” said Peter Wulf-Andersen, Managing director at G.R.A.S. Sound & Vibration. “I am proud that one of the biggest players in the industry has chosen G.R.A.S. as an official partner.”

NI’s new microphone kits include a G.R.A.S. microphone capsule and preamplifier. Inside the capsule is a diaphragm made of a special stainless alloy that provides maximum sensor life. The microphones contain a Transducer Electronic Data Sheet (TEDS) chip and combine with NI DSA hardware to provide a plug-and-play sensor experience.

Field mike!

Meggitt Sensing Systems Launches New Endevco ½” Free-Field Microphone and Preamplifier Set with TEDS Capabilities

Meggitt Sensing Systems has introduced the Endevco® model EM46AE, a combined 1/2” free-field pressure microphone and iTEDS enabled preamplifier (per IEEE 1451.4) set, designed for general purpose and larger channel count precision acoustic measurements within a variety of applications, including vehicle pass-by noise testing; environmental noise analysis; building acoustics; and appliance and other consumer product noise evaluations.

The Endevco® model EM46AE comes in a preassembled kit, consisting of a high-precision condenser microphone and preamplifier, both constructed of stainless steel for high durability. Units are assembled in a clean room environment to avoid contamination of the contacts and are calibrated together to form a reliable acoustic measurement system. These combined units are fully repairable. With a frequency response from 3.15 Hz to 20 kHz and a wide dynamic range of 14 dBA to 135 dB, the Endevco® model EM46AE microphone set is designed according to guidelines set forth by the IEC 61094 Class 1 standard, fulfilling the highest industry standards for acoustic product reliability and precision. Incorporation of iTEDS technology allows for the microphone and preamplifier to be recognized by any smart-transducer compatible input module. When connected, the analyzer will derive information such as microphone type, serial number and sensitivity, which is able to be read by the application software for simplified test setups.

Recommended accessories for use with the Endevco® model EM46AE include the model EM42AA handheld pistonphone calibrator, which facilitates field checks of complete acoustic measurement systems, as well as the in-house calibration of measurement microphones; the model 4416B ISOTRON® power supply (2-20 mA); and the model 133 three-channel signal conditioner. All Endevco® acoustic sensors and instrumentation are also backed by a five-year comprehensive product warranty.

Low-cost array mikes

Automotive, aerospace and general test & measurement applications

Meggitt Sensing Systems has announced the introduction of Endevco® models EM40PH and EM40PL, two low-cost free-field pre-polarized array microphones, designed for multi-channel acoustic measurements of sound power; sound pressure levels and frequencies; sound-field analyses; and concurrent spatial and transient measurements within the audible range in aerospace, automotive and test & measurement applications.

Endevco® models EM40PH and EM40PL offer a wide frequency range of up to 20 KHz.  The model EM40PH is offered with a high sensitivity of 50 mV/Pa and a large dynamic range of up to 135 dB, while the model EM40PL is offered with a low sensitivity of 10 mV/Pa and a large dynamic range of up to 150 dB.  Their highly durable design incorporates use of an SMB connector for ease of test setup assembly and seamless integration with most data acquisition systems. ISOTRON® (IEPE) capabilities allow Endevco® array microphones to be used interchangeably with IEPE-type accelerometers within the same test setups for added convenience. In addition, ISOTRON® microphones have no additional power supply requirements when used within standard 2-20 mA constant current powered systems. Incorporation of TEDS technology allows a microphone to be recognized by any TEDS compatible input module, allowing an analyzer to derive information about microphone type, serial number and sensitivity, which can then be read by the application software. Close manufacturing tolerances and TEDS capabilities provide models EM40PH and EM40PL with the major advantage of a high degree of interchangeability within multiple array matrices.

Endevco® models EM40PH and EM40PL are ideal for use in larger-channel count acoustic measurement applications, such as near field acoustic holography; trending and frequency analysis; white goods testing; automotive and aerospace NVH, or as a lower-cost alternative to a Type 1 compliant microphone in general acoustic testing.  Recommended accessories include the Endevco® model EM42AA handheld pistonphone calibrator and the model 133 three-channel signal conditioner.  All Endevco® acoustic sensors and instrumentation are backed by a five-year comprehensive product warranty.

New microphone sets concept

G.R.A.S. Sound & Vibration (G.R.A.S.) has announced the release of a new microphone sets concept where focus is on simplicity, reliability and robustness.

Uniquely designed based on customer feedback, G.R.A.S. Type 46 Microphone Sets offer a new approach to acoustic measurement data integrity, by reducing user setup and handling errors and improving overall reliability. Sets are available in ¼” and ½” diameters and in free-field, pressure and random incidence types, with specifications developed to support the most common acoustic measurement parameters. They are assembled in a dust-free environment to avoid contamination of the microphone and preamplifier interface; are calibrated together as a single unit; and are sealed with a removable label, for seamless integration into both single- and multi-channel applications. By using these combined sets, mix-ups of microphones, preamplifiers and system calibration data are alleviated.

G.R.A.S. Type 46 Microphone Sets are delivered with individual calibration charts, including sensitivity values and frequency response curves, allowing the sensitivity values to be used directly within system setups. For frequent verification of the measurement chain, a 114 dB sound calibrator is supplied as a sound source. The sets can be connected directly to all pro­fessional measurement systems and are available to support both constant current power (CCP) and 7-pin LEMO inputs. For larger channel count applications, G.R.A.S. Type 46 Microphone Sets also incorporate IEEE 1451.1 (TEDS), allowing for a plug-and-play solution and the ability to identify individual unit properties, types and calibration data, with the added benefits of TEDS onboard memory storage capabilities. In addition, all G.R.A.S. Type 46 Microphone Sets are offered with a 5-year comprehensive product warranty.

Acoustic measurements

New Endevco® Low-Profile Surface Microphone with Integral ISOTRON® Amplifier and TEDS

Meggitt Sensing Systems has announced the new market introduction of the Endevco® model EM40PS, a low-profile surface microphone with integral ISOTRON® (IEPE-type) amplifier and TEDS, designed to facilitate simplified larger channel count acoustic measurements on typical planar and curved surfaces exposed to air slipstreams.

The robust design of model EM40PS requires no microphone holders or stands, and incorporates a dust-free, water-repellant grid cap and a lightweight, detachable silicon rubber fairing, allowing for near-flush mounting on curvilinear surfaces and mounting pads. Models also include an integral 3.3 ft (1 m) coaxial cable with microdot connector. Units offer a nominal sensitivity of 5 mV/Pa (@ 250 Hz), wide audio frequency range from 20 Hz to 20 kHz and large dynamic range from <30 dBA to 136 dB over an operating temperature range of -20ºC to +80ºC (-4ºF to +176ºF) with low sensitivity to base bending. Because of its lightness, the EM40PS contributes very little mass to thin plates, and can be laid flat on its 2” (51mm) diameter rubber pad, or surface mounted using a double-sided adhesive pad for automotive, aeronautical, general acoustics and sound pressure level testing requirements. Pressure equalization is via a vent placed at the front of the microphone by the side of its diaphragm, important for both aircraft usage and on-road vehicle measurements in mountainous country. Close manufacturing tolerances and the advantages of TEDS enable the microphone to offer a high degree of interchangeability, precluding the need for accounting of individual characteristics.

Recommended accessories for the model EM40PS include the model EM42AA handheld pistonphone calibrator; the model 4416B constant-current power supply (2-20mA); and the model 133 signal conditioner. With its unique size and performance characteristics, the unit is ideal for measuring wind-induced noise on ground and airborne vehicles; acoustic radiation surface measurements; wind tunnel noise testing; and for making internal vs. external noise measurement comparisons on moving vehicles.