SSS.6.14 - Research Supplement: Radiant, Omega 300, and Sandman-S Further Analysis
/Rugged Radiant, SilencerCo Omega 300, and Dead Air Sandman-S on a .308WIN Bolt Action Rifle with 20-inch Barrel
The previous Sound Signature Reviews of the Rugged Radiant (6.12), SilencerCo Omega 300 (6.10), and Dead Air Sandman-S (6.11) presented typical sound signatures of the silencers on a .308 bolt-action rifle with an 20-inch barrel. In PEW Science testing, the Radiant achieved a Suppression Rating of 32.9 in its long configuration. The Omega 300 achieved a rating of 38.3. The Sandman-S achieved a rating of 32.6.
This members-only research supplement is intended to provide more information to PEW Science members with regard to specific sound signature characteristics of the tested configurations in the aforementioned reviews and to help frame objective loudness comparisons between the three silencers. This supplement is part of ongoing PEW Science small arm weapon system sound signature research.
Below, summaries are presented for a three-way comparison of first round pop (FRP) and 5-shot average sound performance. Detailed data and analysis follows.
Overall Summary:
The SilencerCo Omega 300 exhibits superior muzzle performance (which correlates to bystander perception) and superior ear performance (which correlates to shooter perception), in both first round pop (FRP) and on average. The Omega 300 therefore earns the highest suppression rating on the weapon system. The Rugged Radiant is quieter, overall, than the Dead Air Sandman-S, but they are both louder than the Omega 300. The Sandman-S seems to exhibit a “higher pitched” sound signature than the Radiant, as shown in analytical human inner ear modeling.
FRP Summary:
When paired with a .308 bolt-action rifle with a 20-in barrel, the Rugged Radiant in its long configuration may have an FRP up to approximately 20% less intense than that of the Dead Air Sandman-S, 1.0 m left of the weapon muzzle. The FRP of the SilencerCo Omega 300 may be up to approximately 26% less intense than that of the Sandman-S.
At the shooter’s ear, the Radiant may have an FRP up to approximately 15% less intense than that of the Sandman-S, or up to approximately 8% more intense than the Sandman-S, depending on the inner ear sensitivity of the shooter between 4,000 and 6,000 Hz. It is likely that the Sandman-S will be perceived as louder than the Radiant. The FRP of the Omega 300 may be up to approximately 62% less intense than that of the Sandman-S at the shooter’s ear.
5-Shot Average Summary:
When considering a 5-shot average, the Radiant may have a sound signature up to approximately 15% less intense than that of the Sandman-S, 1.0 m left of the weapon muzzle. The sound signature of the Omega 300 may be up to approximately 45% less intense than that of the Sandman-S.
At the shooter’s ear, when considering a 5-shot average, the Radiant may have a sound signature up to approximately 11% less intense than that of the Sandman-S. The sound signature of the Omega 300 may be approximately 46% less intense than that of the Sandman-S.
6.14.1 Comparisons of Muzzle Waveforms Measured in the Free Field
It is not always possible to determine relative, objective loudness from only the measured average peak sound pressure amplitude and measured peak sound pressure momentum transfer potential (impulse). Therefore, the Suppression Rating also considers physical ear response to measured sound signatures. The human inner ear responds to different sound pressure frequencies with varying sensitivity. Physically, these frequencies excite different regions of the basilar membrane within the cochlea. The human ear is typically most sensitive to sounds that excite the membrane near a frequency of 4,000 Hz. However, the ear may be exercised, and therefore damaged, at different physical regions. It is postulated that this inner ear response directly correlates to the perceived loudness of suppressed small arms.
PEW Science Research Note: It is important not misconstrue the frequency-domain data in this Research Supplement with a simple frequency analysis (Fourier transform) of the time-domain overpressure waveforms presented in the reviews. The data shown in this research supplement is the output from analytical human inner ear modeling with the measured test data used as free-field overpressure loading input.
6.14.1.1 FRP Muzzle Comparisons
Figure 1 presents the results of an inner ear analysis performed using measured sound overpressure waveforms from the first shots in the three previous tests presented in Sound Signature Reviews 6.10, 6.11, and 6.12. The curves show normalized physical response of the human inner ear as a function of basilar membrane location within the cochlea and corresponding sensitivity frequencies. Fig 1a shows the response on the vertical axis with a linear scale. Fig 1b and Fig 1c show the same data on a logarithmic scale, in the low and high frequency hearing response regimes, respectively. Note that the data is normalized; this lets you see the relative theoretical ear response for the three silencers. To personnel located 1.0 m left of the weapon muzzle, the Rugged Radiant in its long configuration may have an FRP up to approximately 20% less intense than that of the Dead Air Sandman-S. The FRP of the SilencerCo Omega 300 may be up to approximately 26% less intense than that of the Sandman-S. Note the slight bias to potential higher-frequency human inner ear response of the Sandman-S above 4,000 Hz.
Fig 1a. Comparison of FRP Human Inner Ear Response - .308 at the Muzzle (Linear Scale)
Fig 1b. Comparison of FRP Low Frequency Human Inner Ear Response - .308 at the Muzzle (Log Scale)
Fig 1c. Comparison of FRP High Frequency Human Inner Ear Response - .308 at the Muzzle (Log Scale)
6.14.1.2 Five-Shot Average Muzzle Comparisons
Figure 2 presents the results of a second inner ear analysis performed using measured sound overpressure waveforms from the tests; this time, the curves are averages of the analysis of the five shots in each test. Fig 2a shows the response on the vertical axis with a linear scale. Fig 2b and Fig 2c show the same data on a logarithmic scale, in the low and high frequency hearing response regimes, respectively. Note that the data is again normalized. When considering a 5-shot average, the Radiant may have a sound signature up to approximately 15% less intense than that of the Sandman-S, 1.0 m left of the weapon muzzle. The sound signature of the Omega 300 may be up to approximately 45% less intense than that of the Sandman-S.
Fig 2a. Comparison of Average Human Inner Ear Response - .308 at the Muzzle (Linear Scale)
Fig 2b. Comparison of Average Low Frequency Human Inner Ear Response - .308 at the Muzzle (Log Scale)
Fig 2c. Comparison of Average High Frequency Human Inner Ear Response - .308 at the Muzzle (Log Scale)
PEW Science Research Note: Again, note the slight bias to potential higher-frequency human inner ear response of the Sandman-S above 4,000 Hz. This analysis of measured test data indicates that the Sandman-S may be perceived as having a “higher pitched” sound signature to bystanders, on this weapon system.
6.14.2 Comparisons of Waveforms Measured near the Shooter’s Ear
The sound signatures measured at the ear during the tests of each silencer are significantly different than those measured at the weapon muzzle and this difference is not only shown in the average peak sound pressure and impulse measurements, but also with inner ear analysis.
6.14.2.1 FRP Ear Comparisons
Figure 3 presents an inner ear analysis performed using measured sound overpressure waveforms at the shooter’s right ear from the first shots in the three tests. Fig 3a shows the response on a linear vertical scale. Fig 3b and Fig 3c show the same data on a logarithmic vertical scale, in the low and high frequency hearing response regimes, respectively. To personnel firing the weapon, the Radiant may have an FRP up to approximately 15% less intense than that of the Sandman-S, or up to approximately 8% more intense than the Sandman-S, depending on the inner ear sensitivity of the shooter between 4,000 and 6,000 Hz. It is likely that the Sandman-S will be perceived as louder than the Radiant. The FRP of the Omega 300 may be up to approximately 62% less intense than that of the Sandman-S at the shooter’s ear.
Fig 3a. Comparison of FRP Human Inner Ear Response - .308 at the Ear (Linear Scale)
Fig 3b. Comparison of FRP Low Frequency Human Inner Ear Response - .308 at the Ear (Log Scale)
Fig 3c. Comparison of FRP High Frequency Human Inner Ear Response - .308 at the Ear (Log Scale)
6.14.2.2 Five-Shot Average Ear Comparisons
Figure 4 presents the results of a second inner ear analysis performed using measured sound overpressure waveforms at the shooter’s ear from the tests; this time, the curves are averages of the analysis from the five shots in each test. Fig 4a shows the response on the vertical axis with a linear scale. Fig 4b and Fig 4c show the same data on a logarithmic vertical scale, in the low and high frequency hearing response regimes, respectively. Note that the data is again normalized. At the shooter’s ear, when considering a 5-shot average, the Radiant may have a sound signature up to approximately 11% less intense than that of the Sandman-S. The sound signature of the Omega 300 may be approximately 46% less intense than that of the Sandman-S.
Fig 4a. Comparison of Average Human Inner Ear Response - .308 at the Ear (Linear Scale)
Fig 4b. Comparison of Average Low Frequency Human Inner Ear Response - .308 at the Ear (Log Scale)
Fig 4c. Comparison of Average High Frequency Human Inner Ear Response - .308 at the Ear (Log Scale)
PEW Science Research Note: In the five-shot average analysis the high-frequency bias of the Sandman-S is still discernible to the shooter between 4,000 and 6,000 Hz. This analysis of measured test data indicates that the Sandman-S may be perceived as having a “higher pitched” sound signature to the shooter, on this weapon system. This correlates with the data measured and analyzed at the weapon muzzle. This correlation and the potential correlation to anecdotal shooter impressions are both the subjects of continued PEW Science research interest.
6.14.3 Research Supplement Summary
Overall Summary: The SilencerCo Omega 300 exhibits superior muzzle performance (which correlates to bystander perception) and superior ear performance (which correlates to shooter perception), in both first round pop (FRP) and on average. The Omega 300 therefore earns the highest suppression rating on the weapon system. The Rugged Radiant is quieter, overall, than the Dead Air Sandman-S, but they are both louder than the Omega 300. The Sandman-S seems to exhibit a “higher pitched” sound signature than the Radiant, as shown in analytical human inner ear modeling. Although the Radiant is calculated to excite the inner ear more severely than the Sandman-S in certain frequency response regimes, the Radiant will most likely be perceived as quieter and “lower pitched” on this weapon system than the Sandman-S, by both shooters and bystanders.
This supplement is part of ongoing PEW Science small arm weapon system sound signature research. PEW Science thanks you for your support.
