Accurately measuring the noise a firearm or suppressed firearm makes with each report seems like a simple task: download an app on your phone and head out to the range. Not so fast, Alexander Graham Bell. While certain noises produced by stereo speakers, for example, can be measured with simple sound meter devices found on Amazon, gunshots are unique in that the report happens in fractions of a second. In addition, the distance and location from the muzzle (and action), location of the firearm in relation to the terrain and structures, altitude, temperature, barometric pressure and other variables will have an effect on the ability to collect reliable data. Luckily, experts like the engineers at Brüel & Kjær (B&K) have refined their equipment and techniques after decades of research and development and have landed on the Impulse Noise Evaluation System.

If you are a fan of (or at least read) TFB’s Silencer Saturday series, you’ll remember our discussions on MILSTD testing of suppressors as an accurate way to evaluate manufacturers and models. My year-long experience with using the analog, yet still very viable, B&K 2209 sound meter was eye-opening. Measuring the report of a suppressed firearm is a scientific process that should not be taken lightly. The only thing worse than providing consumers with no data is providing them with bad data.

Historically, sound testing for firearm suppressors was conducted with a single microphone placed 90 degrees and one meter away from the muzzle. This was mostly a result of military requirements – hence the MILSTD designation. In recent years, a more consumer-focused testing design has taken shape: along with a muzzle reading, an “at-the-ear” reading has become equally important. B&K has been leading the way to design an advanced sound metering system that places microphones at each ear as well as the muzzle.

The overall system is not cheap and is designed for commercial, not consumer, use. But if you want reliable data you have to use the right tools and procedures. The B&K system is striving to make the most accurate peak measurement possible, so it should be noted that the system will produce dB levels that are different from the B&K 2209. Details from the B&K website can be found below.

Brüel & Kjær Impulse Noise Evaluation System

https://content.bksv.com/impulsenoise

A system for noise measurement of firearms, ammunition and suppressors Provides You:

Accurate impulsive noise measurements for small firearms performed quickly and simply with a mobile battery driven system. A system requiring few cables with hardware & software designed to measure both according to US MIL-STD-1474D and MIL-STD-1474E and for general bench-marking.

Impulse Noise Evaluation for Gun Noise

This solution is a complete, focused kit for acquiring accurate noise measurements for assorted combinations of small arms, suppressors and ammunition types. The system components have been selected to ensure a quick and easy setup, simultaneously acquire the right data the first time, and create the reports with the right data.

USER SCENARIOS

• Performing measurements according to US MIL-STD-1474-D (1997) and US MIL-STD-1474-E (2005) at the range, regardless of whether or not there is a power outlet available
• Benchmarking prototypes or competitor equipment according to comparative impulse noise peak values
• Demonstrate peak values to customers
• Calculate impulse noise limits

CHARACTERISTICS

• The combination of LAN-XI Battery Module Type 2831-A and LAN-XI 3-ch. Input Module Type 3052 enables testing to be performed where you need to test, without being tied to a power outlet
• The three-microphone system enables simultaneous measurement at both ears and muzzle
• The system’s sampling rate of 262,144 samples per second greatly exceeds the 192,000 samples per second required by MIL-STD-1474-E
• Measuring, validating and reporting all in one system