Earmor M31 Review

16 December 2016

Most of us know that loud noises can damage our hearing, but many people don't realise just how easily that damage can occur. Sound intensity (volume) is measured in decibels (dB). The decibel is a logarithmic scale which means an increase of 3dB is twice as loud.

Here are a few examples of how loud everyday sounds are:

A normal conversation is about 60dB.
The sound inside a car on a motorway is about 80dB.
Normal earphones plugged into an MP3 player at full volume is 100dB.
A lawnmower engine is around 105dB.

And here's a list of the sound intensity of various common gun calibres:
Calibre Sound Intensity (dB)
.22LR 130.0
.223 with an 18" barrel 155.5
.243 in 22" barrel 155.9
.308 in 24" barrel 156.2
.30-06 in 24" barrel 158.5
.30-06 in 18" barrel 163.2
12 Gauge shotgun with 28" barrel 151.5
12 Gauge shotgun with 26" barrel 156.1
12 Gauge shotgun with 18" barrel 161.5

Given that a single short sound at 140dB, under the right (or wrong) conditions, can permanently damage one's hearing, you can see from the list above that firing even a single shot from most firearms can cause permanent damage to hearing. Many people with hearing damage caused by firearms don't realise that their hearing is damaged. This is because hearing damage caused by firearms mostly affects high frequency sounds, such as 's' and 'th' sounds. When they hear someone speaking, the person seems to be mumbling or speaking unclearly. By the time they realise that they have damaged their hearing, the damage is quite significant.

While many shooters will wear hearing protection while at a clay shoot, most will not wear any while rough shooting or deer stalking. I've even been ridiculed by others for wearing hearing protection while rough shooting. There are two main reasons why people won't wear hearing protection while rough shooting. The first is that they don't believe that the sporadic shots fired over the course of a day rough shooting is enough to damage their hearing. The chart above shows that this isn't the case. The second reason is that they want to be able to hear ambient sounds, such as animals and birds moving, and other hunters talking to them. This is a great irony in my opinion. They understand how important their hearing is for hunting (not to mention everyday life), and yet they blatantly refuse to protect it! This is where electronic earmuffs are useful. They not only protect your hearing from the loud sounds of gunfire, but they also allow you to hear ambient sounds.

One criticism I've heard about electronic ear defenders is that the electronics take a certain amount of time to react to the sound of the gunshot (a very short amount of time - milliseconds or nanoseconds). Some people believe that in that split second while the electronics are reacting, your ears are exposed to the full volume of the gunshot. This simply isn't true. The hearing protection is not provided by the electronics, it's provided by the sound insulation of the earmuffs - just like traditional ear defenders. Even with the electronics switched off, the electronic ear defenders will behave like standard earmuffs and protect your hearing. There are microphones on the outside of the ear defenders and speakers inside. The electronics simply play the sounds picked up by the microphones through the speakers inside. The sound being played is monitored by the electronics and if a sharp sound is detected, it won't be played through the speakers. Even if, for some strange reason, the speakers inside played the sound of the gunshot, the speakers just don't have the power to play it loud enough to cause hearing damage.

The sound intensity of normal headphones playing at full volume is approximately 90dB - electronic ear defenders would be similar. A gunshot played at full volume through the internal speakers of electronic ear defenders at 90dB would not cause hearing damage. However, longterm exposure to sounds over 85dB can cause damage, so at a clay shoot, firing range or anywhere else that there would be constant gunfire, it is recommended to also wear earplugs inside the earmuffs to provide extra protection.

OPSMEN is a new company, based in China, that develops and manufactures shooting accessories, including electronic ear defenders. I was contacted by OPSMEN a few months ago and asked to review their Earmor M31 electronic earmuffs.

When I opened the package, this is what was inside:

As the product hadn't been launched yet, they didn't have the retail packaging (cardboard box) to send to me. My first impression, when I took them out of the box is that they are solid, good quality and well made. I own a set of Peltor Sporttac electronic ear defenders and when I picked up the Earmor M31s, my first impression was that they are of equal quality as the Peltor Sporttacs.

The M31 is powered by two AA batteries. These are housed in two separate compartments (one in each ear). The screw-on caps of the battery compartments are metal, which adds to the feeling of quality. There are rubber tabs attached to the caps to stop them from getting lost when they have been screwed off.

Battery Compartment

When I put on the Earmor M31, I found the headband was a little narrow for my head but I was able to solve this by bending it outward a little. With the headband adjusted, the M31s are very comfortable. I usually find earmuffs uncomfortable after a while because they cushions are usually a bit hard, but the cushions on the M31 are nice and soft. Even after wearing them for a few hours, they're still comfortable.

Ear Cushion

One complaint I always had about my Peltor Sporttacs is that they pick up and amplify unwanted high-frequency sounds, like a chainsaw in the distance, traffic noise, or the swishing of my feet in long grass. When I turned on the Earmor M31 for the first time and walked outside, the first thing I noticed is that they don't pick up that unwanted background noise. Comparing them side-by-side with the Peltor Sporttacs, the Peltors seem to have a constant hissing in the background, whereas the M31s have a clean sound. There are three sound levels: low, middle, high. I think it would be better if there were five different levels, as sometimes I find one level too quiet but the next one up is too loud. The M31 beeps once when you turn the volume up or down. I don't particularly like this, as I find the beep a little annoying and the beep makes them sound cheap.

Power and Volume Controls

The M31 comes with a 3.5mm audio cable. One end of the cable has a screw-in jack that screws into the auxillary input of the M31, making sure it doesn't get pulled out while in use. The aux-in is useful if you use a radio to communicate with other hunters or if you want to listen to music while waiting in a hide. When I connected my iPhone 6 to the aux-in, I found that I had to turn the volume on the phone up full to be able to hear the music comfortably, so if I was in a noisier environment, I probably wouldn't be able to hear it properly.

Auxillary Cable With Screw-in 3.5mm Audio Plug

Threaded Auxillary Input Socket

When I asked OPSMEN for the Noise Reduction Rating (NRR) of the Earmor M31, they sent this chart and told me that the NRR is 22dB:

As shots from most of the common firearms calibres are in the 155-160dB range, the Earmor M31 will reduce the sound intensity to below the 140dB level at which hearing damage is caused. Obviously, if you are using louder firearms, you will need to use extra protection such as earplugs inside the M31s.

I tested the Earmor M31 while zeroing a .300 Winchester Magnum. I compared them side-by-side with my Peltor Sporttacs and I found the protection to be similar. The shots didn't sound any louder wearing one set or the other. I did find, however, that when I was standing facing into the wind, the wind interfered with the Peltors whereas the Earmors were impervious to it. To be very picky, when listening to someone talking the quality of the sound from the Earmors is not quite as good as the Peltors. The difference is only very slight and it doesn't affect their performance in any way.

The only major fault I could find with the Earmor M31s is with the mechanism for adjusting the height of the earmuff on the headband. At first, it was stiff and difficult to adjust. Three "corners" loosened up with a bit of use, but the forth corner seems to have broken. Rather than holding its position on the adjuster, it moves freely. So far this hasn't been a problem because other side of that earmuff is still strong enough to hold it at the correct height, but I wonder how it will last over time.

Height Adjuster

After I had tried the Earmor M31s, I gave my feedback to OPSMEN (all the things I've mentioned above). They told me that as the model I received was a prototype, not everything had been perfected on it. In particular, they weren't aware of the low volume on the Aux In until I mentioned it to them. They assured me that they would look into the issues I highlighted and fix them before the M31 went into production.

The Peltor Sporttacs and the Earmor M31s are very similar in performance and quality, but the M31s are almost half the price. The Peltor Sporttacs retail for about €110. When I asked OPSMEN what the retail price for the M31 would be, they said about $50. Taking import duty and taxes into account, I think they would retail within the EU for about €65.

Even with the few imperfections my prototype version has, I like the Earmor M31. Of the two sets of electronic ear defenders I have, when going out shooting, I find myself reaching for the M31s more often. They're more comfortable and I prefer the way they perform. All-in-all, if I was asked to recommend a decent set of electronic ear defenders at a reasonable price, I would recommend the Earmor M31. They're comfortable, they perform well and for that money, I think you can't go wrong.

Since writing the review, OPSMEN have informed me that the Earmor M31 is now in production and can be bought from Amazon here: https://www.amazon.com/OPSMEN-Amplification-Canceling-Protection-Electronic/dp/B01M2D82P5/ref=sr_1_1?ie=UTF8&qid=1482568088&sr=8-1&keywords=opsmen

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