Protecting employee hearing and reducing noise in any environment improves comfort, verbal communication, and overall health. Reducing workplace noise can help decrease liability, the costs of hearing conservation programs and personal protective equipment, and the likelihood of injury from overexposure. Below are some examples and tips from my experience as an industrial hygienist for an FDA-regulated pharmaceutical manufacturing plant with several loud production lines and strict quality requirements. I hope you find them useful in your setting or industry.

Observe. Take a walk around the noisy area and just observe the process. Note the types of noises you hear (high-pitched, impact, banging, grinding, compressed air, winding, clanking, and so on) and their locations.

Record. Draw a simple map of the area or obtain a facility drawing. Using a sound level meter or the NIOSH SLM app, plot decibel measurements on your map. The location of your problem areas will become clear.

Investigate. Look and listen for the root causes of noise sources. Follow your ears and your meter as you pinpoint the noise source. For example, one of our facilities has an automated taping machine that made a loud screeching noise as it taped cardboard boxes. We first suspected the noise was generated by friction as the tape peeled off the roll, so we considered trying a different brand of tape. However, we also noticed that the machine had a tape guide rod that had small airholes on the guide surface and a flexible compressed air hose connected to it. So, we thought, “OK, let’s find out if the air pressure is adjustable.” Our mechanic followed the air hose and found a small adjustable thumbscrew, which was fully open. We adjusted down to half-open, and bingo! The noise reduced nicely, and the machine still operated well. Sometimes, as in this case, the root cause is hard to spot, because it occurs while other mechanical parts are moving. It may take many observations and experimentation to find the true source and root cause of a loud noise.

Solutions

The following ideas for reducing noise exposure are based on the hierarchy of controls. Try these yourself, or suggest them to your engineering team or contractor:

Elimination. If a certain loud process or device is not necessary, simply remove it or have it de-energized and locked out. For example, we identified a loud air suction device with no added benefit to production and locked it out.

Substitution. Choose low-noise versions of equipment. For example, compressed-air devices like vacuum generators come in standard models or quiet types that include sound muffler or silencer attachments. Vacuum pump manufacturers make models that are quiet by design; for louder pumps, manufacturers offer noise enclosures. Instead of using compressed air, ask whether the task can be done using another method. At home, I replaced my cheap car tire air pump running at a painful 98 dBA with a low-noise model that runs at a comfortable 73 dBA.

Engineering controls. Several industrial noise vendors offer products such as custom-fit noise enclosures and barriers, food-grade/cleanroom silicone sheets, and aluminum tape to deaden the vibrational noise from impacts to sheet metal and plastic; the tape can also be installed on the feet of a machine or enclosure to reduce vibrational noise. Other products include quiet-by-design compressed-air nozzles for removing debris, cleaning, cooling, or drying. Sound-absorbing ceiling tiles can help by reducing sound reflection and are offered in cleanroom-certified models. Auto shut-off allows a noisy process to be automatically turned off when not needed. For example, a compressed-air parts dryer can be shut off a few seconds after sensing the last part of a batch on a production line. This also lowers operating costs by reducing the duty cycle of otherwise constantly-on compressed air. This system consists of a sensor and actuator and is available off the shelf or can be designed and installed by your company’s automation engineers.

Professional Help

Hiring an acoustic engineer who specializes in noise assessment and reduction can give you a head start in identifying sources, solutions, and a budget for your project. Also, noise control vendors that offer quiet-by-design products such as compressed-air nozzles can give you valuable suggestions via phone or video conference for specific applications. Their tech support is usually a free and useful resource.

Be Persistent

I encourage you to be persistent in finding noise sources and ways to reduce them. As always, seek help from your colleagues and connections, and make it a team effort. Once you’ve succeeded in reducing the noise of one source, you will notice others that were masked by the more dominant sound. For example, after eliminating a loud compressed-air leak, you may now hear the high-pitched ringing of a nearby motor needing refurbishment. This means you’re making progress: you’ve picked that lower-hanging fruit and are reaching higher up the tree.

Related: Read "How to Buy Safer, Quieter Tools" in The Synergist.

Editor's note: This post was updated Aug. 15, 2023, with information about auto shut-off engineering controls.