How Electronic Hearing Protection Works: It's Not What You Think

[Music] there seems to be a lot of confusion on what electronic hearing protection is and how it's different from noise cancelling headphones people seem to think they're the same thing so in this video I'm going to show how they work and what the differences are so here we have three different types of headphones this is electronic hearing protection these are noise cancelling headphones and these are just regular earmuffs so let's take a look at what sound looks like to electronics what I have here is an oscilloscope hooked up to a speaker now speaker is just an electromagnet and a permanent magnet when this moves it generates voltage as you can see on the oscilloscope now I'm gonna use the tone generator on my phone and see what kind of sound wave we get on the oscilloscope when I put it near the speaker [Music] now pause it if we take a look at the oscilloscope you can see it kind of looks just like a sine wave the amplitude is very small because the speaker was not amplified in any sort of way and we're just picking up the frequencies but you can see that it still resembles a sort of sine wave so let's take a look at active noise-cancelling and see what it is and what it looks like on a graph so I've drawn these pictures the sound comes in it goes into a microphone there is a processor on board which inverts the sound and then it reproduces it through the speakers so why do we want to invert the sound now when you take two waves and you invert one of them you get destructive interference and what that means is that the original sound wave is canceled out so if you look at this graph here is the input wave we see it starts with the peak then goes down but the output what this is gonna play through the speakers is the exact opposite the wave is inverted it starts going down first and then goes up so what it effectively does is cancels out this wave now if you'll notice the amplitude is exactly the same both peaks are the same height so here are the noise cancelling headphones here's the on/off switch so they do take batteries they do require power now inside each of the cups it has a microphone that is listening to the ambient sound and it is inverting the wave so that by the time the wave travels through the cup from the outside and gets reached to your ear it has reproduced the exact same sound wave except inverted so that it effectively uses destructive interference and cancels out the sound take note that these cups are very thin and they have no sort of extrusion so when they're on they are not going to be blocking the sound themselves so the itself does not block very much sound from getting to your ears it is all done in the electronics moving on to electronic hearing protection it's similar but still different so the sound comes in it goes into a microphone just as before but instead of going to a sound inverter it goes into a analyzer which turns down the volume essentially when it hears a loud sound it turns the volume to zero and it stops reproducing sound through the headphones so graphically what does this look like well there's gonna be two different options of what's gonna happen so there's either quiet sounds or there's gonna be loud sounds when there's quiet sounds you have your input again notice the amplitude is the quiet sound it's the amplitude is very low and what you hear is a boosted version of this there's exactly the same Soundwave except this is louder and that's what you're going to hear through the headphones so it's amplifying the low sounds the quiet sounds which is what you want now when you get to the louder sounds as you can see the peaks on this are much higher than before indicating louder sounds when that computer detects the loud sound turns the volume to 0 now you might be wondering if it turns it to 0 what is this here and what that is is the response time so it takes a little bit of time usually 10 or 15 milliseconds for the electronics to detect that there's loud sound and to turn the volume to zero here's where the confusion comes in people think that because the response time is 10 or 15 milliseconds that they're being exposed to loud sounds during that amount of time that is not true if you look at the amplitude of this graph you'll see it's very low it's not as loud as the original sound again if you'll notice with the active noise-cancelling the amplitude of the output had to be the same as the amplitude of the input well with electron hearing protection that's not the case the electronic hearing protection is often used for range time when you're going to be around loud sounds like gunshots now if you'll notice the active noise-cancelling has the same Peaks the same magnitude of the peak on the output as the input now let's say you're active hearing protection was active noise-cancelling and you heard a gunshot with it and you tried to make it cancel the gunshot now what that would have to do is reproduce the same waveform as the gunshot and the same amplitude so the tiny speakers in your headphones would have to reproduce the same loudness of sound the same amount of decibels as a gunshot and a gunshots around a hundred and forty to one hundred and eighty decibels which is very very loud now there's no way the little speakers in headphones are able to reproduce 140 to 180 decibels that's just ridiculous that's why they can't be active noise-cancelling so if they're not noise canceling how do they really work what makes them different from regular earmuffs so here are the active earmuffs this happens to be the belt or sport 300 and these are just regular Winchester earmuffs the way these work is both of them actually they use these cups here they make a seal on your head and the cups are what blocks the sound then the difference is on the active ones they have microphones that reproduce the quiet sounds into speakers on the inside so you can hear people talking all of the sound protection is done in the actual cup itself these are no different when this has no power when this is turned off these are exactly the same this blocks all of the sound this blocks all of the sound if you put these on you'll notice that they sound like regular ear muffs that's because they are the electronics are not what protects your ears from damage all the electronics do is boost the quiet sounds so you can hear it you were never in any danger because the loud sound waves from the gunshot are not coming through so how can I show this let's say here's one room and here's another room in between is a soundproof wall so no amount of sound no matter how loud will ever get through to this other side now what you've got here is some TNT and a microphone now that microphone has a wire that goes through and goes to your headphones if this TNT goes off it explodes and it's really loud on this side of the wall remember this is soundproof so you won't even hear it on this side but this microphones here you're gonna hear this explosion through the microphone and in these headphones will you have hearing damage even though this was really really loud no you won't because all you're hearing of the actual noise is just being reproduced from a microphone to your headphones there's no actual loud noise going through the headphones and into your head or into your ears it's all through the electronics so that's why you're not in any danger from hearing loud sounds with the response time even if the response time was infinite even if it never actually muted anything let's say there were no electronics in this all it had was the microphones that played what it heard through these speakers you would still never get any hearing damage because the sounds you're hearing are only as loud as the speaker's can reproduce which is not very loud not enough to damage your ears not nearly 140 to honor and 80 decibels that a gunshot is so you go to the range you have some electronic hearing protection you can still hear the gunshots they're pretty loud still even though you're wearing these a lot of people often think that's because the electronics aren't working they're amplifying the gunshots that's not true what you're hearing is the sound waves going through now every pair of headphones has a noise rating these happen to be 24 decibels I'm not sure what these are but let's say for the sake of argument they're exactly the same now these are just regular headphones like I said before and these are the active ones if I were both of these and they have both the same rating you won't be able to tell the difference of which one's louder and which one's quieter that's because they're not they're exactly the same they have same sound rating and that has nothing to do with the electronics inside that is only the physical construction and the sound absorption from the cups themselves and the materials that they're made of the reason people still complain that the electronic hearing protection isn't working is because the sound rating on active hearing protection is generally not that high these happen to be 24 decibel rating the howard leight impact sports that are very popular they have I believe it's a 22 decibel rating now the lower the decibel rating the less it less sound it blocks like I said the gunshots are around 140 decibels which brings it down to only 118 decibels with the Howard lights like I said before you're not in any sort of risk for hearing damage by wearing electronic hearing protection no matter what the response time is but sometimes they are still too loud because of the decibel rating and that can only be so good that has nothing to do with electronics that's again it's all in the construction of the headphones themselves these would have the same problem what you can do is put a set of foam earplugs underneath and then turn up the volume that way you can still hear people talking around you yet when you hear a loud sound you'll have the foam earplugs in and you'll hear less of that loud sound ideally you want to find and buy electronic hearing protection with the highest decibel rating you can find now these are again they're twenty fours the Howard lights are twenty twos and the Howard lights are pretty cheap which is why they're so popular but if you want the maximum protection while still being able to hear the people around you you're gonna want to buy a more expensive one I know the this is the again this is the belt or support tactical 300s the belt or sport tactical 500s have a twenty twenty six decibel rating yeah that's what it is twenty six decibels and I'm sure they make even more expensive headsets that have even higher decibel ratings which is ideal and you can buy gel cups for of the headphones which will help seal it even better and increase that decibel rating so that you can have the maximum amount of hearing people around you while also maximizing how much hearing protection you actually get so in summary active hearing protection is not the same thing as active noise-cancelling and you are not at any risk by wearing active hearing protection you are at no risk of hearing damage any more than you are for wearing regular headphones thanks for watching everybody I hope I have cleared up some of this confusion on the differences between noise cancelling headphones and electronic hearing protection and I hope I have successfully convinced you that there is no risk of hearing damage by wearing electronic hearing protection versus regular headphones if you like this video please leave a like comment share and subscribe if you have any other suggestions for other electronic things that you have questions about maybe I can explain them in a future video so go ahead and drop a comment down there tell me what you want to see what kind of things you want explained and I will do my best to make a video on those thanks everyone [Music]

Channel: Budget Tool Reviews

Views: 31,207

Rating: 4.8980169 out of 5

Keywords: Peltor Tactical Sport 300, tactical sport 500, howard leight impact sport, electronic hearing protection, noise cancelling, shooting, range gear, earmuffs, guns, 3m, active hearing protection, safety, ear pro, how does electronic hearing protection work, how electronic hearing protection works

Id: w1_fo4PwOBw

Length: 13min 42sec (822 seconds)

Published: Tue Jan 02 2018