Sound Testing Protocol

The microphone positions follow the arrangement described in MIL-STD-1474E. One microphone sits to the left of the muzzle at 39.5 inches (roughly one meter) off the bore line. The second sits at the shooter’s ear, 5 inches off the bore and aligned with the end of the buffer tube. Both microphones stand 5 feet 4 inches above the ground.

We test in a free field, at least 100 feet from any reflecting surface. The ground beneath the setup is raked mulch.

Wind speed is measured at the moment of each shot with an anemometer. MIL-STD-1474E allows a crosswind of up to 5.8 mph (9.3 km/h) between the source and each measurement location. We discard any shot taken above 4.5 mph, holding a margin below the standard’s limit for a safety buffer and improved shot-to-shot consistency. MIL-STD-1474E sets no upper or lower humidity limit; we forgo high-humidity days rather than test through them.

In cold weather the ammunition and test rifles are kept at 80 °F, so that a suppressor is always measured somewhere in the 80 to 95 °F band.

Each test is split into two kinds of shots, recorded and averaged separately.

The first is first-round pop. We fire three cold-bore shots. Between each, a barrel cooler chills the chamber back toward ambient and replenishes the oxygen inside the suppressor, so the next shot starts from the same cold, re-saturated state. Each cold-bore shot gets roughly five minutes under the chamber fan before the next.

The second is the regular string: shots fired 15 to 25 seconds apart. First-round-pop shots and regular shots are never averaged together.

Every capture is a single shot. Our application locates the shot’s onset, the first sample where raw pressure crosses 1 Pa (about 94 dB), and computes every metric over a fixed 100-millisecond window from that point. All levels are decibels referenced to 20 µPa, through the relationship L = 20 · log₁₀(pressure ÷ 20 µPa).

We compute four numbers from that window:

Peak dB: the highest positive overpressure in the window, converted to decibels.

Peak dB(A): the same peak, taken from an A-weighted copy of the signal (A-weighting per IEC 61672).

Peak Impulse (Pa·ms): the integral of pressure over time through the positive-overpressure phase of the blast.

LIAeq100ms: the A-weighted equivalent continuous level, the root-mean-square energy of the A-weighted pressure across the full 100 ms window, expressed in decibels. This is the metric we publish as our primary figure.

All four metrics are averaged across the included shots in the linear domain: the Pascal (or Pa·ms) values are averaged first, and the mean is converted to decibels once at the end.