NASA Publishes Acoustic Dataset from STRIVES5 eVTOL Tests

What happened? 
National Aeronautics and Space Administration - NASA’s Vertical Lift Stratos (STRIVES5) campaign—the first to publicly release comprehensive eVTOL noise measurements—deployed a groundarray of 58 GRAS 67AX pressure microphones to capture in-flight acoustic data from new electric aircraft prototypes.  

How were they arranged? 
These precision microphones were embedded in specially designed 400 mm ground boards, arranged across a hemispherical measurement array to provide full coverage of sound emission angles during eVTOL overpasses.  

Why GRAS  67AX? 

  • Designed for aerospace ground-array measurements, it offers a frequency range from 3.15 Hz to 20 kHz, dynamic range of 22–150 dB(A), and a lowprofile pressure sensor embedded flush in the plate—ideal for mitigating windnoise and groundreflection effects. 

  • Embedding the diaphragm into the board avoids highfrequency nulls from diaphragmtoboard reflections—a significant improvement over older invertedpressure setups. 

Data Highlights & Public Release 

NASA published raw acoustic and flightpath data alongside atmospheric conditions—an unprecedented open dataset for eVTOL noise modeling. 

These measurements advance understanding of urban air mobility’s environmental sound footprint and support future noise regulation. 

Why It Matters 

Benefit 

Description 

Comprehensive coverage 

58 high-fidelity microphones provide hemisphere-level sound mapping 

Standardized instrumentation 

Flushmounted GRAS 67AX plus WAMS II systems ensure clean, consistent acoustics data  

Open data access 

Enables researchers and urban planners to model eVTOL noise impacts more accurately and transparently 


Looking Ahead 

Following STRIVES5, subsequent phases—including a phasedarray of 117 GRAS 67AX sensors—will further isolate noise sources (main/tail rotors, ducted fans)  

This work paves the way for quieter, community-friendly eVTOL design and certification frameworks. 

Questions? We’re Here to Help! 

If you have any questions about the GRAS flushmount microphones or how they’re used in eVTOL acoustic testing, please don’t hesitate to get in touch. 

Contact: Lars Winberg 
Lars is ready to assist you with expert guidance on selecting the right microphones for your aerospace noise measurement needs — and to share insights from NASA’s groundbreaking work. 

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