The sound of silence

Feature article by Dick Henneman

There’s an old saying that “silence is golden”, and as far as biking is concerned, that’s certainly the case if you’re the rider (or the pillion for that matter). That new end can you bought may make wonderful music when you wind it on, and the induction growl from the bike’s airbox might send a tingle up your spine, but even with the quietest helmet on the market, at legal motorway speeds your ears may be subjected to noise levels fifty to a hundred times higher than the allowed industrial limits. And you don’t have to be travelling to get a good dose of noise. Just sitting in a traffic jam can hit your ears with noise levels approaching Concorde during take-off. This is not good. Your passion for motorcycling could risk making you deaf. There’s no cure and it’s not reversible.

So what’s the answer? Well, it’s quite simple – use earplugs.

“But I’ve ridden for years without ear plugs and haven’t had any ill effects”. That’s quite possibly true, but I bet you’ve had ringing in your ears from time to time after a run, and each time that happens you’ve done some damage. Deafness due to exposure to high sound levels is cumulative, and it can be thirty to forty years before you notice a problem. In pretty much the same way that smoking a cigarette isn’t going to kill you overnight, but in later life however you’re going to be a sure-fire candidate for lung cancer.

Convinced now? Well I hope so, because the alternative could be learning sign language and lip reading before you’re sixty.

Earplugs are either disposable or made-to-measure re-useable.

Disposable earplugs come in four basic types; pvc foam, down-filled, polyurethane foam, and rubber, but which is best for you can only be found out by trial and error. Just because the press gives one particular brand a good write-up doesn’t mean that it will work for you, it just means that they worked for the journalist. You don’t know whether his ears are the same as yours, and how noisy was his helmet? You’ll want to use an earplug that’s comfortable and fits well, but you also need to know how effective it’s going to be in cutting down that damaging noise. For this you need to know its SNR value, and to explain what this is we’re going to have to get technical for a moment.

The SNR is the “single number rating” that determines the amount of noise protection that the plug offers over an averaged spectrum of sound frequencies, and it’s derived from the EN352 European standard. Earplugs designed for use in noise hazard areas should be tested to this standard and they can then be CE marked. But this in itself doesn’t mean that they’ve ‘passed’, just that they’ve been tested. The higher the SNR value, the greater the level of noise attenuation the earplug will offer. It’s not a linear scale though, and an increase of three gives twice the protection, an increase of six gives four-times the protection, and an increase of eight gives nine-times the protection. Values of commercially available plugs range from around 22 to 35, but for bike use 27 is about as low as you’d want to go. If you’ve got a noisy helmet, and most of them are – even the expensive ones, or you’re doing high speed work like track days then you should be using an earplug with a much higher value that this.

The made-to-measure and re-usable earplug is custom-made for the shape of your ear canal and isn’t usually tested because the one-off test cost would be prohibitive. So there’s no way of knowing how well it will work, and the harder material that they’re made of is usually less effective at absorbing noise. And not only are they fairly expensive, but as your ear canal shape constantly changes as you age, they’ll need replacing every couple of years. This means that you’d have to get through an awful lot of disposable plugs in a twenty four month period to make them cost effective and you’d be unlikely to have such good noise protection during this time.

Of the disposables, down-filled are generally the least effective and most have low SNR values. The earplugs are slim plastic sheaths filled with fibres and some people find them difficult to fit in their ears. You also need to be careful about damaging the outer sheath, as it can be very dangerous to get the bare fibres in the ear canal. Foam pvc plugs have medium SNR values and are perhaps the longest-running type of plug around. The pvc material is quite resilient and for some it can make this type of plug a little uncomfortable, although others swear by them. The greatest range of earplugs are made from polyurethane foam which is more comfortable, gives a better fit for many than pvc, and also has better noise attenuation properties. These make them suitable for very noisy environments. Both these types of foam plugs have to be rolled up before they’re inserted in the ear. Finally there’s rubber plugs. These are a straight push fit and many have a rigid stem that can be useful if you’ve got dirty hands(?). However, they’re much less affective then either of the foam types. If you’re the kind of person that’s prone to dropping things like earplugs in muddy car parks, then you might want to consider plugs joined together with a cord. Many types of earplug have a corded option and the cord can be useful to help getting the plug out of the ear. But don’t tug the cord sharply or you could tear it away from the plug and be left with a lump of foam stuck in your ear (been there, done that, but failed to find someone who could sell me the T-shirt!).

Earplug Type Make SNR
PVC Foam EAR Classic 28
  EAR Grande 34
  EAR Amigo 28
Polyurethane Foam Laserlite 35
  Multimax 35
  Max 34
  Maxlite 34
  3M-1100 31
  Down Bilsom 202 27
Rubber Airsoft 30
  Quiet 28
  Ultrafit 25
  Comfifit 24

Although disposable plugs are supposed to be use-once and throw away, most can be cleaned and re-used a couple of times if you’re careful. The rubber ones can be washed and re-used without problems and pvc earplugs can be cleaned around three times before they should be discarded. Polyurethane foam plugs are not supposed to be washed, but I’ve found that if you’re careful then one clean up is possible. Only down earplugs really can’t be washed at all. Earplugs should be washed in warm water with a little detergent, fully rinsed and carefully dried before use. But whether new or cleaned, make sure that the plug is OK before you fit it in your ear. If there are any signs of damage then throw it away and use another one.

And that’s about it. There’s no law that says you have to use earplugs when riding your bike, but you’ve only got one set of ears and for around only 50p for a pair of disposable earplugs it’s worth hanging on to them.

Thanks to Lucy Dell Earplugs (http://www.members.aol.com/lucydellearplugs) for technical advice. You may want to pay them a visit and stock up...

 




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