How Do Electronic Hearing Protection and Amplification (Shooter's) Ear Muffs Work?

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If you are not familiar with electronic shooter's ear muffs, here is a brief explanation of how they work. Fundamentally, the passive hearing protection provided by the ear muffs protects your hearing from loud noises such as are produced by gunfire or loud machinery. Inside the muffs are electronic components including microphones that pick up sound from outside the ear muffs, an amplifier that makes low volume sounds in the environment easier to hear with the muffs on than with the uncovered ear, and speakers that project the amplified sounds to your ear from the inside of the ear muffs.

The amplifier used in electronic earmuffs includes the "smart" capabilities of the ear muffs. In older (and many cheaper) models, the technology was a simple "stop gate" technology. These ear muffs would amplify low level sounds, and when the sound level picked up by the external microphones reached a dangerous level, the amplifier would simply turn off, leaving the user with the passive protection provided by the earmuffs. When the dangerous sound went away, the amplifier would resume amplifying the environmental sounds. The speed at which the amplifier could switch between off and on, is referred to as "attack time." The faster the attack time, the less the user is cut off from being able to hear what is going on around him.

More expensive and advanced models feature the latest amplifier technology, generally referred to as "sound compression." This technology lets you continue to hear all of the sounds in the environment, but compressed into a lower-volume stream of sound that is essentially continuous, without the on-off sound you get with stop gate technology. With sound compression you hear more than you can without the ear muffs, but all at a safe volume level. Older (and many cheaper) models contain just one or two microphones. With these ear muffs on, the user can hear low level sounds because they are amplified, but the small number of microphones makes it difficult to determine the direction from which the sound is coming. More expensive electronic ear muffs generally feature 2 microphones on the outside and two speakers inside each ear cup, which give the user an excellent sense of direction. Directional sensitivity is extremely important in hunting and military/police tactical situations, and a very nice feature in virtually all other applications.

In summary, the following features should be considered when buying any electronic hearing protection and amplification ear muffs:

  • NRR rating. The electronics in the ear muff do not protect your hearing. Only the ear muffs can do that. Make sure you get an NRR rating high enough to provide the protection you need. Small caliber weapons call for a minimum NRR 20. Larger bore hand and long guns call for NRR 25 or better, and for large caliber and magnum handguns, long guns and shotguns, the highest rating you can get (NRR 33) is appropriate. Dual protection which includes wearing ear plugs under your electronic ear muffs, is also recommended for large caliber practice. In general, you will need more protection when practicing due to the number of muzzle blasts to which you are exposed. Similarly, indoor shooting calls for higher, and/or dual protection due to the sound being trapped and echoed within the room.
  • Number of microphones. To achieve acceptable directionality of the sound you hear, each ear cup must have at least one microphone on it, and separate speakers in each ear cup to let you hear from which side the sound is coming. A better arrangement is to have two microphones and two speakers in each ear cup. This arrangement will let you tell not only which side the sound is coming from, but also whether it is coming from in front or behind you. This sort of directionality is critical for hunting, police and military tactical situations, and a very nice to have feature in all applications for electronic ear muffs.
  • Compression vs. Stop Gate Technology. Sound Compression technology means you hear a continuous stream of sound without the on-off sound you get with a stop gate amplifier.
  • Attack Time. The faster the attack time, the less you will find yourself cut off from surrounding sounds as the amplifier turns on and off. Sound compression also benefits from fast attack time, resulting in fewer losses and greater fidelity of sound.
  • Maximum Volume. Electronic ear muffs vary widely in the level of amplification they can provide. The best ear muffs offer a 50 decibel maximum amplification, which gives the user "bionic" hearing that is much better than the user has without the ear muffs. Virtually all electronic ear muffs let you adjust the volume from off to maximum and anywhere in between, so more amplification at the maximum is better. Industrial hearing protectors usually feature a built in limiter, so the sound you hear cannot exceed a safe level, even if you turn them all the way up and leave them there all day! Although this is a good idea for those subject to occupational safety regulatory control, it is better to have a set of ear muffs that let the user set the volume where needed for the current situation, which can often exceed long term safety levels. Of course you need to use good judgment and not expose yourself to excessively loud sounds any longer than necessary. Remember, hearing damage occurs as a result of a time-volume level combination. Louder sounds will do damage more quickly than will lower sounds. When in doubt, turn it down!
  • Independent ear cup controls. Some electronic ear muffs give you a single control, which means the same amplification in both ears. A better arrangement is to have independent volume controls on each ear cup. That let's you adjust the volume in each ear to suit your personal preferences and to overcome minor hearing loss in one ear if that is necessary. This is very common, especially among shooters.

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