Peripheral Hearing vs. Hearing Protection




Contradiction or Compatibility? A dialogue on this issue by Steve Tocidlowski

November 2000

Wearing a communications headset of any type, even if on or over only one ear, affects one’s peripheral hearing. This diminution of natural hearing affects a person’s sense of direction and distance and thus limits what is buzzword referred to as “situational awareness”.

Many localities have outlawed the use of hand held cell phones or headsets while driving, for instance, due to the threat (real or inferred) of being able to hear approaching dangers and hazards. Leaving aside the idea of the driver being distracted by the conversation (another issue), the current trend is to solve the situational awareness issue by “hands free” speaker kits. To solve this problem in a tactical environment, where privacy is an issue, current trends are to use “non-occluding” earpieces in or over the ear, or bone conduction receivers that do not cover the ear.

There is also a question of comfort when blocking one ear with a headset or earpiece. Users will feel “off-balance” or they may feel that their voice is unnatural sounding when they speak. If both ears are blocked, the balance problem is eliminated but the peripheral hearing is greatly reduced and the person will not judge his speech level well.

To block both ears is often a necessity, however. Users working in high noise levels must block the amount of sound reaching their ears to avoid hearing damage or to improve work efficiency. Explosive sounds such as gunfire are also dangerous and should be blocked.

What, then, is the solution to achieving both hearing protection as well as complete situational awareness? This obvious problem has been solved in some of the following ways. The first, probably the most common, is to ignore the problem either by sacrificing peripheral hearing, hearing protection, or privacy of communications. The second method is to combine “talk-through” systems, either passive or electronic, into a communications headset/hearing protector. The 3rd method is to use non-occluding earpieces and augment them with a separate hearing protector with a “talk-through” system.

“Talk-through” systems can be passive, such as by using a membrane to stop explosive impulses while allowing normal speech to go through, but they are controversial in the sense of effectiveness. Electronic types are now more common which simulate one’s natural hearing (or even enhancing sensitivity) with a microphone on the outside of the hearing protector and reproducing the surrounding sounds into an earphone. These electronic types limit the reproduced sound to the maximum safe allowable sound level, but the protection offered the ear is strictly relative to the effectiveness of the earpiece or earmuff to block high sound levels.

Note that in constant high noise, talk-through systems are not always practical. The reproduced sound, even if at safe levels, may be an annoyance. A way to differentiate speech from surrounding noise would be desirable. Active noise reduction, another technique to reduce constant high noise from reaching the ear, is another technology solution, but has many limitations and considerations (not addressed here) and power consumption requirements.

Perhaps a practical solution for the tactical user, is the electronic talk-through system with the ability to turn it off when in constant noise environments. In low noise environments, it can provide protection against sudden unexpected noise such as gunfire or breaching/distraction devices and even enhance hearing for intelligence purposes. A cautionary note however: increased sensitivity changes the sense of distance of sounds. A volume control or three way switch (off-normal-enhanced) may be helpful.

Earmuff type hearing protectors are available with communications capability, as are in-the-ear or behind the ear types. To combine in-the-ear communications products such as Invisio with an in-the-ear talk-through hearing protector seems like a logical step. A matched pair of talk-through earpieces, one in each ear would give full balance, situational awareness, and protection!

The issue becomes that of technical problems in combining the communications device, the marketing of the product as competition to earmuff systems and the proving/testing of the degree of protection. Establishing NRR ratings to hear-through systems is problematic. The best consideration, however, for this approach is that a hearing protector is only good when it is worn. Carrying an earmuff headset or wearing it at all times is an issue, especially when heat (sweat factor) and carrying weight is a problem. Helmet compatibility with earmuffs are often a problem, but so is the discomfort (if any) of earmolds and problems with ventilating the ear canal to avoid fungus or infection. Custom molding of earpieces is an obstacle to sales, especially with transient users (changing personnel).

Further discussion is encouraged on these issues, please contact Steve Tocidlowski at T.E.A. POB404, Brewster NY10509 or e-mail: tea-ny@msn.com

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