Ultra Thin Microphones


The World´s Thinnest Condenser Microphones


Validation of CFD (Computer Fluid Dynamics) modeling is an important part of designing vehicles that move in airflow. However, airflow and turbulence cannot be fully simulated and predicted realistically – CFD methods do not provide all the answers needed in the design process. For these reasons, high-quality measurements are a must.

Only very small, thin, and aerodynamically correctly shaped sensors can overcome these challenges – validating the modeling AND supplying the additional measurement data needed.



"Turbulence is the most important unsolved problem of classical physics"

-Richard P. Feynman-
Nobel Prize Winner in physics 

This is why we at GRAS have developed the UTP microphones – Ultra-thin Precision microphones.

UTP microphones are surface-mounted condenser microphones with all the expected quality and precision of a classical measurement microphone. They beat any flush- or surface-mounted microphone on the market - superior performance, unbeatable price, fast and repeatable mounting – and should be a first choice for cost-effective, high-precision testing.

In essence, the UTP microphones are FLAT, FAST and PRECISE - ideal for measurements in boundary layers and turbulence.
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New UTP Microphone Family

Meet our New UTP Microphone Family

The GRAS Ultra-Thin Precision (UTP) Microphones provide the ability to understand boundary layer and turbulence noise on different vehicles. The UTP microphones disrupt today’s manufacturing practices and are based on patented technology.

UTP microphones combine the high precision and reliability of GRAS measurement microphones with the need for extremely low-profiled (less than 1 mm) microphones with minimum turbulence influence. With their unique form factor and easy mounting, UTP microphones are specifically designed for in-situ boundary layer testing, when neutral impact and high precision is important. Together with our range of Surface and Flush microphones, UTP microphones cover all boundary layer testing applications in the automotiveaerospace and other industries.

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GRAS 48LA Ultra-Thin Precision Microphone

48LA UTP Microphone, High Pressure
48LA is for high pressure applications. It has a built-in preamplifier and is terminated with a Microdot connector.



See the specifications here >

GRAS 48LA Ultra-Thin Precision Microphone

48LX-1 UTP Microphone, Medium Pressure
48LX-1 is for medium pressure applications. It has a built-in preamplifier, has TEDS and is terminated with a Microdot connector.



See the specifications here > 

GRAS 48LA Ultra-Thin Precision Microphone

48LX-4/ -8 UTP Line Array, 4/8-Channel, Medium Pressure
48LX-4/ -8 is a line array with four or eight 48LX-1 microphones mounted on a strip. The strip is a thin, flexible PCB that has been designed to also act as a mounting flange even on curved surfaces. Both have TEDS and are terminated with one single splitter cable D-Sub for either BNC or Microdot.

See the specifications here for 48LX-4 or 48LX-8 >

GRAS Boundary Layer White Paper

Turbulence and Measuring in Boundary Layers

A new white paper examining measuring in boundary layers in flow without disrupting the measurement environment and new tools for acquiring valid, actionable data without damaging the item under test.

Download White Paper >

Ultra-Thin Precision Microphones

The GRAS UTP microphones introduce a significantly reduced form factor to the world of condenser measurement microphones. Add to this, clever mounting, cabling and verification options and the result is very tangible benefits - small things which make a BIG difference.

Superior Performance - Unbeatable Price

Explore the benefits, the very small things which make the BIG difference

>  Quality data from precision condenser microphones

>  Extremely low profile making it ideal for testing in boundary layers and turbulent flow

>  Small form factor allowing for use in difficult-to-access spaces and confined cavities 

>  Fast and repeatable mounting ensuring accurate and repeatable results



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 >  Easy in-situ verification even on curved surfaces – a major advantage for in-field measurement setups

>  Cost saving and efficient solution due to fast mounting and repositioning

>  Flow-optimized fairings ensuring minimal disturbance to the sound field/airflow 

>  CCP technology, simple connectivity to avoid interference and TEDS for all 48LX versions


Disruptive Concept


"The new Ultra-Thin Precision microphones from GRAS Sound & Vibration fundamentally change automotive aeroacoustic testing!"

-Leading Asian OEM-

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Tiny - therefore ideal for small cavities. Line array versions ideal for mildly curved surfaces.


"The bendable UTP strip allows us to mount sensors on curved surfaces of the car body. And we really like the fact that we can easily calibrate all mounted channels in-situ with the calibration adapter"

-Leading European OEM-


Explore the Design

  • Low profile - just 1 mm.

  • 1/4" condenser microphone.

  • Wide frequency range - 10 Hz to 70 kHz Wide dyn. range - 54 dB(A) to 170dB.

  • Integrated cable. The line arrays come with a single cable with D-Sub.

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  • Small footprint.                    

  • Edge for click mounting in hard fairing.

  • Hole for safe removal from the fairing.

  • CCP technology for easy integration with existing hardware.

  • TEDS for easy sensor identification.

Easy Mounting and In-situ Verification

The UTP microphones are easy to mount, demount and remount. Fast and reliable in-situ verification saves time and increases confidence.

Mounting - Fast and Repeatable
The single UTP microphones can be mounted in a hard fairing which can be used as a permanently mounted dock. A click mechanism ensures easy and stable mounting. The microphone can easily be removed, leaving the mounting position ready for future measurements. The fairing is secured with double-sided adhesive tape.

The UTP line arrays are mounted using masking tape. Reproducing a previous setup can be done quickly and geometry is maintained.

In-situ Verification
A special verification adapter RA4800 with a soft cushion allows for quick, easy and reliable in-situ verification. Four distance spacers ensure that the correct volume is achieved and that this volume can easily be reproduced.

Even on slightly curved surfaces, this verification method is so precise that demounting is not necessary.


Vehicle aeroacoustic performance has a strong influence on customer perception and also has importance for safety and comfort. Measuring wind noise performance depends on minimizing aeroacoustic noise sources generated by various vehicle components. Wind noise is, however, often an issue, which is discovered late in the development process.

Flow behavior and noise generation are inextricably linked in any aeroacoustic measurement test. The three main categories within automotive aeroacoustics, which affect the aerodynamic noise on a road vehicle are the vehicle form, open cavities and body sealing.



The identification of acoustic and aeroacoustic sound sources on aircrafts has always been a challenge in in-situ environments due to the complexity of the sources and the tough environment. Predominant sources of noise are the sounds from the engines and sounds of the wind flowing around the aircraft as it moves through the air.

Simulation is cumbersome as the acoustic models are complex and the calculation time-consuming. Verification of the CFD (computational fluid dynamics) models by experimental measurements is required.



Boundary layer measurements have been a general challenge for research engineers for years. Although these challenges differ across the automotive, aerospace, renewables or consumer goods industries, the issue of being able to separate the microphone induced influence on the turbular flow has long been difficult to overcome – be it in simulated or in-situ environments.

Reliable data and benchmarks have therefore been difficult to achieve both in the development and testing phases – and in particular all tests have been time consuming and cumbersome.


GRAS UTP Microphone Brochures

Download our brochures

With all the expected quality and precision of a classical measurement microphone and an ultra-small form factor, only 1 mm (0.04 inches) in height, the UTP microphones beat any alternative surface microphone in the market – superior performance, unbeatable price, fast and repeatable mounting – and should be a first choice for cost-effective, high-precision testing.

The World´s Thinnest Condenser Microphones >

Measurement Microphones for Aeroacoustics >

At GRAS, we build on our heritage by constantly pushing the limits of what is possible to help our customers improve their products. This is why we have the industry´s most advanced microphones and acoustical test solutions optimized for critical applications.

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Innovating Acoustic Sensors