High-Tech Hearing Protection

Hearing protection devices

A few of the different types of
hearing protectors I use in my studio.

Hearing Protection Overview

For some time now I have been looking for a set of high-tech earmuffs to use around my studio. Although I have several different types of models now, none of them really rise to the level of protection I need when working around loud machinery for long periods of time. Through the years, I’ve purchased numerous types of hearing protectors including slip in earplugs, foam earplugs, silicone earplugs and several varieties of over-the-head earmuffs designed for noisy environments like gun ranges, industrial settings and similar situations.

All of these hearing protectors utilize passive hearing protection and all of them fell short of what I felt I needed in certain situations. After a long day with the chainsaw, or when I was in the studio working with the air compressor or using my right angle grinders for carving, I could tell that my current earmuffs were not up to the task. In an attempt to improve my hearing protection, I doubled up and used earplugs with my over-the-head earmuffs.

Ear plug

Some of the different types of ear plugs available.

This helped a bit more than earplugs or earmuffs by themselves, but I still felt that I needed more protection. I consider myself at a high level of risk because I work around noisy equipment on a regular basis and quite frequently, for extended periods. I’ve always been conscious of safety issues and I frequently research new products that will improve my overall safety in the studio. When it came to hearing protection, I bought the best passive protection earmuffs I could find and coupled that with a very good set of earplugs.

The problem is that not all noise is created equally. According to the National Institutes of Health, long-term or repeated exposure to sounds at or over 85 decibels can cause hearing loss. In a woodturning environment, we can easily approach this threshold and in some cases, far exceed it with some machinery or tools. Hearing damage caused by noise is known as sensorineural hearing loss, or nerve deafness. Noise induced hearing loss can be prevented, or reduced with proper protection.

Passive Hearing Protection Devices

Over-the-head ear muff

Over-the-head passive style earmuffs like these do little to protect against harmful low frequency noise.

Common passive hearing protection strategies include the use of earplugs that are inserted into the ear canal and over-the-head/behind-the-head earmuffs that cover the entire outer ear. Passive hearing protection devices utilize acoustic foam or other materials to block noise waves from entering the ear. Passive hearing protection devices are useful for protection against some types of noise, such as mid frequency and high frequency generated noise.

These helmets, 3MPAPR (left) and Husky hard hat (right), feature passive-style hearing protection.

Unfortunately, passive protection devices are not very effective against low frequency noise, like the noise generated from fans, motors and engines. Since low frequency noise producing devices are common in a woodturning environment, we need to look for more effective protection to ensure we are providing the highest level of protection against noise levels that would cause hearing damage. That means if you’re relying on common passive style earmuffs or earplugs, you may be placing yourself at risk for noise induced hearing loss.

Examples of Noise Levels from
Various Types of Machinery

Manual Machine Tools: 80dB
Electric Drill: 95dB
Power Saw: 110dB
Chainsaw: 125dB+
Resaw Bandsaws: 100dB
Portable Woodworking Tools: 101dB
Routers: 103dB
Pneumatic Drills/Heavy Machinery: 120dB

The Problem – Noise Induced Hearing Loss (NIHL)

When you are exposed to sounds that are too loud, or sounds that are too loud over time, sensitive hair like structures inside your ear called cilia can be damaged causing noise induced hearing loss. When we hear a sound, the sound moves through our ear canal where it strikes the tympanic membrane. These sound waves cause the tympanic membrane to begin vibrating, which in turn cause tiny bones inside the middle ear (malleus, incus and the stapes) to begin moving.

The stapes sends the vibrations through a fluid filled coiled tube in the inner ear called the cochlea. This vibration causes the cilia to move, which change the movement into electrical impulses that are sent into the brain through the cochlear nerve. The cochlear nerve sends these impulses to the cerebral cortex where your brain interprets them as sound.

Each specialized hair cell in your ear has stereocilia on the top of it. As sound enters the ear, these cilia move back and forth. If the sound is too loud, the cilia can be bent or broken, causing the hair cell to die. Once the hair cell is dead, it can no longer transmit sound to the brain. Here’s the kicker… If you damage these specialized hair cells in your ears, it’s permanent – they will never grow back.

The high frequency hair cells are the easiest to damage and as a result, it’s not uncommon for some people to have trouble hearing high frequency sounds like birds chirping. So the question is how do we as woodturners protect our hearing when working in the studio, or outside the studio? We need protection from a wide variety of machinery and tool noise, including those produced in the low, mid and high frequency levels.

The Solution – Active Noise Reduction (ANR)

Some high tech hearing protection devices employ sophisticated electronics to provide protection for the most complete level of hearing protection available today. The technology is known in the trade as “ANR” or Active Noise Reduction, which adds additional protection for low frequency noise, which is difficult to eliminate with traditional passive hearing protection devices. By combining high quality passive protection and active noise reduction electronics, ANR earmuffs provide a more complete level of protection against the harmful levels of high, mid and low frequency noise levels.

Noisebuster's model PA4000 earmuffs with
active noise reduction feature.

After a lot of searching on the Internet for industrial hearing protection devices and active noise reduction earmuffs, I came across a company called Noisebuster that offered earmuffs with active noise reduction technology that is well proven in industrial environments. Combining a 26 NRR passive noise cancellation (CSA Class A, SLC (80), 29.2 Class 5) earmuff with up to an additional 20dB (20Hz to 800Hz frequency range) of active noise cancellation, the Noisebuster earmuffs were just what I needed in my studio. The earmuff is powered by one AA battery and will last up to 65 hours of use on a single battery. There is also a standard 3.5mm audio interface cable if you want to listen to your favorite tunes from your MP3 player.

Noisebuster model PA4000 active noise reduction earmuffs

This bottom view of the Noisebuster earmuffs shows the ANR switch on the far left center and the 3.5mm audio interface connection next to it on the right.

These earmuffs are made for industrial environments and are resistant to moisture, shock, contaminants, and vibration. The ANR feature can be switched on and off at will, by pressing a small button located on the right earmuff. When the ANR circuitry is switched off, the muffs operate like traditional passive hearing protectors and provide 26dB of passive protection. When the ANR circuitry is switched on, up to 20dB in additional noise cancellation is available for protection against harmful low frequency noise.

How Active Noise Reduction Works

According to the Noisebuster.net website, “The Noisebuster ANR system uses a microphone inside the earcup to listen to noise coming into the ear. Using electronics, the system takes that information and uses it to create a noise wave that is identical to, but directly opposite of the one coming into the ear. The anti-noise wave is output through a speaker located inside the earcup. When the two waves meet (the noise wave and the anti-noise wave), the noise is significantly reduced.”

Noisebuster “ANR” Earmuffs in Use

I’ve been using my Noisebuster Active Noise Reducing over-the-head earmuffs (model PA4000) for a few weeks now and I love them! They have been such good performers that I will be purchasing two more sets (the kind that is made to mount in a hard hat, model PA4200) to use with my 3M PAPR powered respirator and my Husky hard hat. These earmuffs utilize a special mounting bracket that slips into the side of hard hats/helmets that are equipped for earmuffs and do not feature an over-the-head cushioned band.

This side view of the Noisebuster earmuffs shows the red light, indicating the active noise reduction feature is in use.

The difference is perceived noise when using these earmuffs is quite simply, amazing. I wear them all the time now for chainsawing, caving with my right angle grinders, using my diamond blade wet saw, working on the bandsaw, using my air compressor and reciprocating carvers, when using outdoor power equipment and even when vacuuming. When my order comes in for the helmet mounted models, I will be using them anytime I’m in my studio, since I will be installing one of the units on my 3M PAPR respirator that I wear in the studio. I’ll also be using another set that will be installed on my Husky hardhat, whilst I’m using any outdoor power tools, chainsaws and the like, or when working around any type of machinery outside that produces objectionable noise levels.

If you’re wearing traditional passive earmuffs, or using simple earplugs, I highly encourage you to invest in a pair of the Noisebuster earmuffs. The over-the-head model I’m currently using (PA4000) cost me $149.00… It’s the best money I’ve ever spent in the entire 16 years that I’ve been a professional woodturner. Hearing loss can creep up on you and it can be permanent. Do yourself a favor and get yourself a pair of these bad boys. Your ears will be glad you did!

Note: Noisebuster also offers an optional amplified speech module, a two-way communications module and a Bluetooth module that will allow you to answer cell phone calls without removing your headset. In addition to the over-the-head model, a behind the head model is also available if you prefer.

Safety Note: Always follow all manufacturers safety instructions before working with your lathe, or any of the tools or products you may use. If you are unsure about any operation, obtain competent professional instruction before proceeding. Use and wear all necessary safety devices during turning and observe safe woodturning practices to prevent accident or injury.

Steven D. Russell is a professional studio woodturner, teacher and writer. He has written numerous articles for international woodturning magazines, which have been published in more than 78 countries around the world. Steve has demonstrated in numerous cities across the United States. His studio, Eurowood Werks, specializes in bowls, platters and hollow forms with unique visual and tactile treatments.

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