Law enforcement agencies use Acoustic Surveillance Devices (ASDs) to assess threats, identify suspects, monitor suspicious activity, and evaluate incidents. An ASD is a microphone that can be connected to a radio transmitter, recorder, or set of headphones, and is designed to collect and relay or record information. Effective deployment of ASDs, integrated with additional sensor technologies (e.g., thermal imaging devices, video cameras), provides real-time data necessary for agency response to criminal activities or emergency incidents.
To assist with the acquisition of ASDs by law enforcement and emergency response agencies, an assessment of ASDs was conducted. Ten Commercial Off-The-Shelf (COTS) ASDs, consisting of four contact microphones, four parabolic dish microphones, and two Radio Frequency (RF) body wires, were selected for the comparative assessment.
Law enforcement and emergency response practitioners operated each ASD in controlled scenarios. The contact microphones and parabolic dish microphones received overall product ratings according to evaluation criteria in four of the SAVER Program categories—affordability, capability, deployability, and usability. RF body wires received overall product ratings according to evaluation criteria in three SAVER Program categories—affordability, capability, and usability. In addition to the overall product ratings, quantitative sound fidelity ratings were determined by the sound source levels at which the practitioners could detect, recognize, and identify the sound source over various distances. Qualitative sound fidelity ratings were captured as part of the capability assessments. In general, the overall product ratings were in relative alignment with the quantitative sound fidelity ratings, with the exception of the contact microphones.
Both of the assessed RF body wires performed exceptionally well. However, the more expensive RF body wire, the JOEY 2, received slightly better ratings than the LEA 97178. The least expensive contact microphone, the ASV-1, received the highest overall product rating of the contact microphones assessed; however, the CM-30, FOS, and LD3 were not far behind.
There is a separation between the ratings of the top two and bottom two parabolic dish microphones. The Dan Gibson and the Detect Ear received the highest ratings of the parabolic dish microphones assessed. The PALD-06 and the SCI-BIONIC received the lowest ratings of the parabolic dish microphones assessed.
The overall results of the assessment are highlighted in the following table:
Parabolic Dish Microphones
Radio Frequency Body Wires