When suddenly facing loud noise and there is no time to put on earplugs or earmuffs to protect hearing, it is essential to know how to effectively use one’s hands to protect the ears. However, it seems way too common that people do it the wrong way which can both mean inadequate protection and also even amplify the uncomfortable sounds that you want to protect your hearing from.
It seems especially common among kids to intuitively protect their ears by cupping their hands over the ears. This is not a good way and will not provide sufficient protection. An alternative but only slightly better method is to push on the tragus (see image below) to cover the ear canal. However, by far the best protection using your hands is provided by inserting a finger into each ear canal. These so-called finger plugs can protect the hearing almost as good as earplugs, so can be seen as a great alternative when you didn’t bring any earplugs or earmuffs without you and/or when you want to protect yourself from a very quick exposure to loud noise.
This recommendation is supported by a research study. In order to assess which method of natural hearing protection by using one’s hands that works best for protecting yourself from loud noise, the company Brüel & Kjær created a head and torso simulator to replicate the response of a real ear and the effects of hands placed over them.
Three methods were evaluated:
1) Cupping a hand over the entire ear
2) Pushing on the tragus to block the ear canal
3) Placing the tip of a finger into the ear canal
Some key findings from the study were:
— Both holding in the tragus and covering the entire ear gave very similar results. This feels surprising, but could be due to small air gaps still being present, through which sound is transmitted into the ear canal.
— The level reaching the microphone when using these two methods is hardly affected, and although some of the sound above 2kHz is being absorbed by the hand, the cavity created by cupping the ear or pushing on the tragus is causing an amplification of around 10dB below 2kHz.
— Pressing on the tragus appears to provide slightly better high frequency attenuation (above 8kHz) than cupping the entire ear, which may be related to the size of the air gap that is allowing sound to propagate into the canal.
— Placing a finger directly into the canal and blocking it provides the most amount of attenuation of the 3 methods. Above 100Hz this method provides 20-30dB’s worth of attenuation across the spectrum, a considerable reduction in level. Below 100Hz there is an increasing amplification down to 20Hz due to the occlusion effect. This is caused by bone conduction of low frequencies caused by the body (movement of the jaw etc.) reflecting off of the object blocking the canal and being transmitted to the ear drum. This sound would normally escape the canal into the air when not occluded, which is why we don’t normally notice it.
Hence, the conclusion is that when you are in a loud environment and don’t have access to or the time to put on any hearing protection such as earplugs or earmuffs, the best method of lowering the sound level reaching your ear is to insert the tip of your fingers into the ear canal. This will provide you with a substantial reduction in noise level (minus the occlusion effect) across the whole audible frequency spectrum. This can be the difference that saves you from hearing damage.
If you are a parent, please teach your children this method of using their finger tips as earplugs, since too many kids tend to cup their hands over the ears when they are suddenly faced with loud noise. There are a lot of everyday noise situations where you will not be able to be there quickly enough to protect them. I am thinking of sudden exposure to industrial machinery, building sites, leaf blowers, excessively loud motorcycles etc.
Source: Natural Hearing Protection: Hands? // Image: Emiliano Horcada
Leave a Reply