Got Protection – The Data

by | Jan 2, 2019 | Group Riding, The Track, Touring | 4 comments

This article is © 2019 arc@arcnineohnine.com and may not be reproduced without written consent. 

This is part three of an in-depth three part article:

  • Part One “Got Protection” explains why motorcyclists need hearing protection and covers important sound concepts used in parts two and three
  • Part Two “Plug me up” addresses the types of hearing protection standards and how to correctly fit and maintain earplugs
  • Part Three “Got Protection – The Data is a detailed and comparative review of thirty-four different earplugs

If you’re looking for a summary: as a motorcyclist wear high protection earplugs. To know why and which ones to use, read on but please read each article in order as they build on each other.

You won’t get the full benefit of this article if you haven’t read the previous two as they explain key concepts which are used in this final article, for example in part two the significant differences in the three hearing protection standards and why that’s important in making decisions about which plugs are right for you (decibels aren’t always the same, it depends on how you measure them) and in part one how sound is measured and why you need hearing protection every time you ride (it’s the wind noise that’s often far worse for your hearing than engine noise and this can be at 60 km/h) plus why even a one decibel difference in protection is important (three decibels is a doubling of the sound intensity/power!).

 WHICH ONES?

What’s important to you when choosing an earplug? Lifespan? Sure, but that’s a tough one to review in any reasonable time frame. Here’s my criteria

  • Provide the right protection – as mentioned in Part One – Got protection?” I often tend to go on day long rides of six to eight hours and hence I want the maximum protection I can get: an SLC80 rating of ≥ 29 dB should mean that I don’t suffer hearing loss from my rides;
  • Comfortable – can be worn for hours without causing irritation
  • Fit fast – tank to tank is typically 200+ kms and it’s nice to be able to hear the service station attendant without mumbling or shouting at them, when having a break being able to talk with my fellow riders and when the time comes to depart not spend an eternity fiddling with ear plugs which take ages to expand and properly seal;
  • Cheap – a relative concept but only a few dollars a  month; and
  • Easy to obtain – with Internet ordering this really isn’t a problem, it’s not like they’re hard to source online but do remember that, as we learned in Part Two – Plug me up, there are different international standards which can make it difficult to easily compare plugs.

Given my requirements I sought Google search’s advice. That took some considerable time and I’ve summarised my findings in these articles so that you don’t have to spend an eternity trawling through web pages and more importantly are educated as to what to buy. Why’s that important? Part of my very early research led me to believe that a particular earplug would be perfect so I bought 80 pairs online but later I found that these plugs simply wouldn’t cut out wind noise as much as I’d expected and whilst the online advertising indicated that they’d be the highest protection possible at NRR 33, under the SLC80 standard these same plugs are rated at 23dB, compare this with the plugs I’m now using which are SLC80 29dB – remember that we learned in Part One – Got protection? that “an increase of three decibels is approximately a doubling of [sound] power”. That’s a HUGE difference in attenuation.

Some riders don’t know what their ear plugs are supposed to be cutting out, some use “Race” earplugs which barely attenuate at the needed frequencies, many don’t use hearing protection at all and many also don’t know which ones to buy and stick with whatever they can easily find or have been given by a mate.

So, how did I decide which ear plugs I’d test? Earplug Superstore offer a range of different ear plug packs including a “highest protection assortment” of thirty-four different foam ear plugs for US$10.90. There may be other great plugs on the market though; the multinational conglomerate 3M’s extensive and vast range of hearing protection products alone could take years to review.

MEASUREMENT METHOD

How’s a mere mortal like me going to be able to come up with a repeatable scientific and evidence based method to choose the best earplugs? The ANSI/ASA standard S12.6-2016 “Methods for Measuring the Real-Ear Attenuation of Hearing Protectors” sells online for $150 (US?) and it’s exceedingly unlikely that I’d have the sound proof chamber and testing gear to be able to put this to good use. Perusing the other excerpts from standards documents didn’t help either. I need a better way, perhaps a MacGyver way.

I’m using a Sena 10U Bluetooth headset on my Arai RX-7V and found an Android app called Hearing Test that uses the same method that professional hearing folks use to determine hearing loss, this is called pure-tone audiometry and per the app’s website “is the basic hearing examination which determines the degree of hearing loss in relation to the sound frequency”. They provide profiles for specific headphones which come bundled with many different handsets. Perfect. Sure it won’t have a profile for my Arai/Sena Bluetooth set up but I don’t need that. I simply need a way to measure every set of ear plugs and at what decibel level l hear each test frequency, hey, after that all I need is a baseline reading with no plugs in and I’ll be able to  measure exactly how much attenuation each earplug provides.

So how does this pure-tone audiometry test work? A tone is generated in one ear at a set frequency and you tell the app if you can or can’t hear it, if you can then you keep telling it that you can hear it as the app gradually reduces the decibels for that tone until you can’t hear it anymore then you backtrack until the sound is just audible, then you move on to the next tone and finally repeat the process for your other ear. At the end of the test you get a chart similar to the following (red is my right ear, blue the left):

Which tells me that for this particular set of ear plugs with a tone generated at 250 Hz frequency, I could only just hear it at 40 dB “of volume” . From the below baseline test without this earplug I could hear the same frequency sound at 15 dB meaning that these earplugs reduced the sound volume by 25 dB at 250 Hz.

Hang on a sec, how about those negative values in the above baseline, isn’t that an error? Not per say, it’s a relative number: at a 4,000 Hz frequency tone the baseline is -10 dB and the plugs tested at 35 dB meaning that at that frequency the plugs knocked off 45 dB of volume.

Hmm. What about this author’s ears, are they “perfect”? Unlikely due to my age, many awesome days spent at The Big Day Outa love of music and motorcycles plus small bore rifle and twelve gauge shotguns will have taken their toll. But it’s the best method I can use to see how these plugs work for me. Will your mileage vary? Yes, but this gives me the most scientific and consistent measure that I can use to rank the effectiveness of different earplugs.

Other considerations? Well yes, glad you asked. Standard deviation is calculated during SNR/NRR/ SLC80 rating tests and with manufacturing being what it is no two ear plugs will ever be precisely 100% the same. In my test results I’ve calculated the “mean minus standard deviation” (abbreviated to MMSD) which for  an NRR 33, SLC80 29 dB ear plug at 6,300 Hz (where a lot of wind noise is found) reduces the sound volume by on average 45.1 dB (instead of 49.3)

Frequency (Hz)125250500100020003150400063008000
Mean Attenuation (MA) dB42.343.746.640.938.644.746.949.348.3
Standard Deviation (SD) dB565.84.22.83.23.34.23.6
Mean Minus Standard Deviation (MMSD) dB37.337.740.836.735.841.543.645.144.7

But what about plugs that don’t provide test data? Personally I won’t use plugs which don’t provide hearing test data. To me having this test data means that they’ve not only attained the relevant test certification but that they’re being transparent with their data. Don’t just rely on a single SNR or NRR number as you’ll want to see at what frequencies these plugs provide hearing protection. For some manufacturers like Moldex and 3M the test result data was really easy to obtain, for others it was like being waterboarded (I kid you not).

THE PLUGS

Here are all the plugs which I tested, click on any image to enlarge:

TEST RESULTS

WIth size often being called out as important and to kick things off, how big is each plug? With a set of vernier calipers I measured the width a few millimetres from the tip (the bit that first goes into your ear) and the end (the bit that sticks out of your ear canal) and the overall length of each plug, remember though that we’re dealing with soft foam which doesn’t easily lend itself to highly accurate measurement.

For each plug I also rolled it into the smallest size possible and then timed how long it took in seconds to match its other pair, I repeated this test by flattening vertically and timing this too – this latter test was more for shits and giggles as this is not how you’d use one of these plugs but does give another indication of the time taken, when deformed, for each plug to return to its natural shape.

Next I tracked down the SNR/NRR/SLC80/class details. Some included this on their packaging but for many it took considerable hunting around online. For the Elvex Blue/Uni-Fit and all four of the Got Ears plugs I couldn’t locate certification test data.

The cells in the below table are colour coded vertically to help make it easier to see differences between earplugs –  ranging from dark GREEN to RED. All online data was sourced between November 2018 and January 2019.

TEST RESULTS – SIZE, REBOUND & RATING

Yeah, it’s a lot of information packed into one table. You’ll see that some plugs appear to be perfect (high attenuation) if you only look at the NRR rating, which for many is the highest possible at NRR 33, but see for example how the Elvex Uni-Fit plug has a SNR of 37 with a corresponding NRR of only 32 compared with the two Howard Leight plugs which have a NRR of 33 and are rated as class 5 but only an SLC80 of 26 (vs the highest SLC80 of 29). Yep, you might need to read that last sentance a few times LOL.

It is important to review all the standards for each plug and at the same time review the actual frequency reduction across the ranges too. This is why choosing hearing protection isn’t that simple as two plugs with a NRR of 33 can have quite different SLC80 ratings and may offer very different ranges of protection at different frequencies, more on this later.

TEST RESULTS – MANUFACTURER TEST DATA

Below are the manufacturer test results which I sourced online. NB different testing methods are used and results are *not* comparable between different test types. Again I’ve colour coded each column based on the values in each vertical cell (so that you can see attenuation at specific frequencies).

Below is just the “brand” and a new “average” column (excludes 3,150 and 6,300 Hz results) created from the data in the above chart, sorted by “average”: 

Cool, so based on the data in the three tables above I can now easily select “my” earplugs, especially with the simple table above with just an average? No – remember that the above test data was from different test methods and isn’t therefore comparable.

Hmmmm…tricky. What to do? That’s one of the reasons I wanted to see how they actually stood up in real world use, hence the Sena 10U/Arai RX-7V/Hearing Test (pure-tone audiometry) testing that I conducted with the results in the following tables below.

 

 

TEST RESULTS – ARCNINEOHNINE’S

Below are the results of my personal tests using the Sena 10U/Arai RX-7V/Hearing Test (pure-tone audiometry) method.

  • If there was a discrepancy between ears I averaged the result of the left and right ears;
  • Testing was conducted at quiet times in the morning/late evening; and
  • Legal disclaimer – Arc NineOhNine’s test results must not be used to choose hearing protection products nor are they to be used to compare manufacturer products.

 

and now for the money shot

 

TEST RESULTS – ARCNINEOHNINE’S DETAILED RANKING

Remember how we talked about the frequency range of sound in previous articles? Yes, it’s important to know which frequencies you’re being protected from so in the below you’ll see

  • An average attenuation across all seven test frequencies (“average” in the third column)
  • An average only for the 250 and 500 Hz range
  • An average for the 1,000 to 8,000 Hz range
  • An average for the 2,000 to 8,000 Hz range
  • An average for the 4,000 to 8,000 Hz range

This table is sorted by “Average 4-8” then 2-8 then 1-8 and finally by 250-500. Colour coding of values is as before (vertically through each frequency/result).

Why did I sort/use these specific frequencies for ranking? Most wind noise is higher up in the frequency range and I want to reduce these specific frequencies from my riding. I also wanted to have averages across different frequency ranges so that I could see if certain plugs had high attenuation at higher frequencies but relatively “bad” attenuation at lower frequencies.

 

FINAL THOUGHTS

  • What ear plugs should I use? That’s your call. I can’t tell you nor can I suggest what you should or should not use – there may be potential health implications and I am not medically trained. You need to make up your own mind;
  • On the cost of custom vs disposable plugs I came across an article from Howard Leighton (Honeywell) indicating that disposables might be cheaper long term than custom moulded earplugs; and
  • One disposable foam plug manufacturer stated that
    • ear plugs must be disposed of and replaced after each wearing
    • washing and cleaning of disposable earplugs [is] not recommended
    • excessive moisture reduces the attenuation and slows down the foam recovery which may lead to improper fit

 

What hearing protection does Arc NineOhNine use? Today I’m using disposable foam ear plugs having had three sets of custom moulded plugs made, had reusable plugs and many different types of disposables too. Which brand and model are you now using? Come see me on a ride and we can discuss that.

 

ArcNineOhNine, January, 2019.

 

%d bloggers like this: