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Focused Enhanced Acoustic-Driver Technologies (FEAT) for Long Range Non-Lethal Hail and Warn Capabilities



OBJECTIVE: Develop a Focused Enhanced Acoustic-Driver Technology (FEAT) for Long Range Non-Lethal hail and warn capabilities. Provide long range non-lethal hail and warn capabilities to deny access into/out of an area to individuals, move individuals through an area, suppress individuals in open and confined spaces, and stop vehicles and vessels by providing intelligible voice commands to vehicle/vessel operators.

DESCRIPTION: Typical Commercial Off-the-Shelf (COTS) acoustic hailing devices (AHDs) employ an array of acoustic drivers in their systems that produce peak acoustic outputs (Sensitivity – anechoic) of ~ 109 dB. These acoustic arrays also employ acoustic beamforming techniques using 8 or more single acoustic drivers to produce maximum peak sound pressure levels (SPLs) at 1 meter in excess of 156 dB (A-weighted). To meet current DoD Hail and Warn range performance requirements, these COTS AHD (arrayed) systems get very large (e.g., > 64 inches in diameter) and very heavy (e.g., > 350 pounds), and are expensive (e.g., > $100K) [Refs 1-2]. Improving the range and voice intelligibility performance of these hail and warn devices is dependent on 4 primary AHD system performance specifications: (1) increasing the acoustic output levels of each of the acoustic drivers (measured in SPLs); (2) increasing the gain in delivered SPLs achieved by employing adaptive beamforming techniques [Ref 3]; (3) improving the clarity/intelligibility and sound penetration capabilities of the voice/warning signal commands delivered at range through complicated battlefield atmospheres by using lower frequencies (e.g., projecting audible frequencies (in-air) from ~ 100 – 2500 Hz) [Ref 4]; and (4) implementing an atmospheric compensation algorithm that will allow for better targeting of individuals at distance in typical battlefield atmospheres.Increasing the acoustic output levels of the acoustic drivers from 109 dB to 123 dB or greater is a technical challenge. This 14 dB increase in sound pressure level (SPL) equates to a 14X increase in AHD loudness as this is a logarithmic scale. This increase will require research to develop stronger magnets but with lower mass and stronger diaphragm materials to increase overall system reliability. The resulting full-system acoustic driver, which includes the magnet, compression driver and direction horn, shall weigh less than 3 pounds. The AHD shall also incorporate an adaptive beam forming algorithm that will increase the maximum peak sound pressure level output of the entire system. Maximum SPLs in excess of 156 dB (A-weighted) shall be achieved. Improved voice intelligibility shall be achieved at ranges in excess of 2000 meters by employing focused low frequency sound (projecting sound in the 100 – 2500 Hz frequencies ranges). These low frequencies propagate better near the ground and just above the air/water surface, and also penetrate better into structures and confined spaces such as vehicles and/or buildings. Finally, this next-generation AHD system shall incorporate an atmospheric propagation correction tool to allow for better target aiming at range, i.e., the tool will correct for normal acoustic beam refractions in the atmosphere and for windage.The newly developed next generation compact/lightweight AHD will achieve long range hail and warn at ranges in excess of 2000 meters. The next-gen AHD will incorporate enhanced acoustic drivers (with single acoustic driver outputs of > 123 dB), an acoustic beam forming algorithm, projection of lower frequencies (100 -2500 Hz) for improved voice command intelligibility, and an atmospheric compensator tool to allow for better more precise aiming.

PHASE I: Develop concepts for an improved (more compact/lightweight and longer range) acoustic hailing device (AHD) that meets the requirements described above. This includes developing (1) an improved (123 dB) acoustic output driver design, (2) an optimum adaptive beamforming algorithm for this AHD, (3) low frequency sound projection for improved voice command intelligibility at long ranges, and (4) an atmospheric compensator tool incorporated into the AHD for better targeting. Demonstrate the feasibility of each of these four key AHD subsystems in meeting JNLWD/Marine Corps needs through material testing and analytical modeling, as appropriate of each of the four key sub-systems, as well as for the resulting improved AHD system. Establish that the concepts can be developed into a useful product for the Joint Services. Provide a Phase II development plan with performance goals and key technical milestones, and that will address technical risk reduction.

PHASE II: Develop a next-generation AHD prototype for evaluation to determine its capability in meeting the performance goals defined in the Phase II development plan and the Marine Corps requirements for the next generation AHD. Prototype and test all four key subsystems of the new AHD. Evaluate the system performance of each of the 4 key subsystems and the next-gen AHD system prototype. Confirm and modify the modeling and the analytical methods developed in Phase I to include measuring the required full range of parameters including numerous deployment cycles. Use evaluation results to refine the prototype into an initial design that will meet the JNLWD/Marine Corps hail and warn requirements. Prepare a Phase III development plan to transition the technology to Joint Service use.

PHASE III: Support the JNLWD/Marine Corps in transitioning the technology for Joint Service use. Develop the next-generation Acoustic Hailing Device for evaluation to determine its effectiveness in an operationally relevant environment. Support the JNLWD/Marine Corps for test and validation to certify and qualify the system for Joint Service use.A compact, lightweight, long-range acoustic hail and warn capability has significant commercial applications beyond the DoD. Other government agencies, such as the Department of Justice (DoJ) and the Department of Homeland Security (DHS) to include Customs and Border Patrol have actively been researching these types of AHDs to again deliver voice command warnings at ranges in excess of 2000 meters. Local civilian law enforcement specifically conducts missions to support both building entry, clear-a-space, and orderly evacuation. Currently overall system size, weight, and cost have hindered the use of these systems by these agencies. This SBIR topic specifically addresses overall system size, weight, power consumption, thermal cooling, and cost all while drastically improving AHD performance.

KEYWORDS: Acoustic Hailing Device, AHD, Acoustic Drivers, Compression Drivers, Acoustic Adaptive Beamforming, Voice Intelligibility, Acoustic Atmospheric Compensator Tool


1. “LRAD 1000RX Remotely Operated, Integrated Communication Systems Datasheet.” Long Range Acoustic Device (LRAD) Corporation, San Diego, CA., 2017 2. Scott, Richard J. (Joint Non-Lethal Weapons Directorate) and Eggert, Joseph (Naval Surface Warfare Center Dahlgren), Distributed Sound and Light Array (DSLA) Lite - Balikatan Experiment 5 MAY 2014, Quantico, VA, 5 May 2014. Wikipedia, Adaptive beamformer,, 10 May 20194. Brixen, Eddy B., “Facts About Speech Intelligibility.” DPA Microphones Inc.

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