How to get Favorable Results on Sound Tests
Unspecified methods can allow someone to claim to test to MIL-STD-1474D but in fact get amazing results by omitting details of the test.
MIL-STD-1474D is a military standard that was designed for generic hearing damage risk assessment. It is possible to affect the results of any test, including the military standard test, by not specifying your exact procedure.
Many manufacturers do not specify their testing protocol and this makes their results incomparable to other results. Our tests done on the same day are more comparable than one manufacturer's test to another. We specify how we test.
When comparing our tests to others, consider questions like these:
1. What ammo are they using? We use normal full power ammo and pick something popular -- that perhaps a police agency would buy or the military would use. We specify whatever we pick. Are the 9mm results from a manufacturer using 147 grain ammo from Winchester, Remington, Black-Hills, or some other popular company? Maybe not. It is common for silencer-manufacturers to use low power ammo because it gives quieter results than ammunition more suitable for self-defense or police/military use. Ask them what ammo they tested with and then ask yourself if you would use that ammo for serious use.
2. What were the environmental conditions before and during the test? We do not favor one can over another, and store them in identical conditions. Waiting for a humid or rainy day may give a nice net reduction. Ask them what environmental conditions the silencer has been exposed to before testing. If the silencer is left out overnight it might collect dew which would help the score.
3. Did they report all of the data? Did they do a true ten-shot average and use all of the numbers, or just pick the best number of the day? We report a true average.
4. Did it have water or excessive grease? Grease might be needed for a silencer to function or to keep threads from seizing, but we have found unnecessarily large amounts of grease in some samples which would affect results. If we notice grease or water in a silencer, we will remove it or report that it was there. If you demo a silencer and it is smoking, it has grease or some other medium in it.
5. Has their equipment been calibrated? We have calibration certificates available for viewing. Ask others if they have a certificate that is less than one year old. We calibrate our gear for each session with a B+K pistonphone at 124.0 dB at 250 Hz (where most microphones are most accurate). Others often calibrate at 1000Hz and 94 dB SPL (1 Pascal) which is further from the sound level of suppressed gunfire but lower cost and more convenient.
We make every attempt to have our numbers be average and typical and do not do anything to favor one can over another. We are not doing this for profit and do not have any stake in the outcome except to help the consumer make a decision. Ideally everyone would test every silencer by themselves, but this is usually not possible. We are here to provide honest results that reflect the reality of the product better than we often see published and tend to agree with what we heard with our ears during the tests.
Contents are Copyright 2005 by Robert Silvers and may not be reproduced without permission.