Hear ye, hear ye

Keep workers in touch with electronic hearing protection

While ear plugs and conventional muffs can reduce a worker’s exposure to sound levels, they can also isolate them from other workers and dangers around the jobsite, affecting productivity, and in extreme cases, safety.

“People are naturally social. Hearing protection can isolate them from the work environment,” says Bill Schubach, vice president of sales and marketing at American Allsafe. “That isolation can reduce workers’ ability to communicate with others, hear audible alarms or other sounds that can keep them out of danger,” he says.

That isolation can also hinder hearing protection use because they must take off the hearing protection device (HPD) to communicate with others.

Electronic HPDs may be a solution
The electronic HPDs offered by a variety of manufacturers are perking up contractors’ ears who want to provide their workers with needed hearing protection without isolating them from their work environment and others.

According to Aearo Safety and NIOSH reports, the electronic muff-style HPDs typically offer a noise-reduction rating (NRR) of 19 to 26, compared with ear plugs that offer 12 to 33 NRR and semi-aural protectors offer 17 to 27 NRR. “Generally, a 10 to 15 NRR is appropriate for many construction jobs,” says Mark Stephenson, research audiologist at NIOSH.

The electronic HPDs use built-in microphones and micro-circuitry to monitor sound levels. The units automatically knock the peaks off of sound levels greater than 82 dB(a) and transmit that signal to the speakers in the muffs. The speakers are specially selected for their ability to transmit sounds in the human voice range.

“These communication headsets allow workers to clearly communicate with fellow workers, which will improve productivity and safety,” says Mike Cimino, Peltor product line manager at Aearo. “They are like a bionic ear. They can help improve compliance because the user does not have to take the muffs on and off to communicate with others in his or her surrounding environment.” he says.

Cimino adds that those who already have some hearing loss may also benefit from the muffs because they amplify important ambient sounds while minimizing or eliminating loud, irritating sound levels.

A variety of electronic HPD models are available. Hear-only muffs are the most basic models found in most product lines; older technology models use microphones that shut off sound transmission when they sense a sound greater than 85 dB(a). “They are fine for infrequent impulses such as shotgun or powder-actuated tool shots, but on jobsites where there are often many sounds producing greater than 85 dB(a), the muffs shut off almost continuously affecting the worker’s ability to hear,” Schubach says.

Newer, more advanced units use compression circuitry that takes incoming sound and reduces it before transmitting it to the muff speaker. The microphones sense the sound in a way that it gives the user a sense of 360-degree hearing ability. In addition to modifying incoming noise so the user is not exposed to sounds any greater than 82 dB(a), it also processes sounds in the human voice range — 62 to 67 dB(a) — and boosts it to 82 dB(a) so the user can hear human voices better.

“The units are designed to process only those frequencies that are in the human voice range, typically from 400 to 4,000 Hz,” says Roland Westerdal, president of Elvex Corporation.

The next step up in electronic HPDs feature models that can receive radio signals. Depending on the brand and model, they can receive AM and/or FM radio stations. Models that receive music or talk radio can help improve worker compliance and increase productivity on loud jobs where the work is repetitive and there is little need for two-way communication. “This gets to the social aspect of people. Studies show if they can listen to talk radio, sports or music of their choice, they are more productive,” says Schubach.

More sophisticated models have a built-in two-way radio and can receive 14 license-free channels. Workers can tune in to the channel their fellow workers are using to receive or give instructions, says Cimino.

These headsets incorporate the latest in boom microphone noise-canceling technology for clear discussions even in high-noise situations. They also allow cell phones or two-way radios to be used via a separate patch cord.

 “The people who need these are the ones wearing a radio or carrying a cell phone on the jobsite,” says Schubach. They are also helpful for workers who need to communicate with each other across distances, such as truck drivers and dozer or excavator operators, he adds.

 “This allows users to wear hearing protection yet still be able to hear and communicate with others,” says Cimino. “It can greatly improve compliance because the user will not miss calls or pages or have to remove the HPD to communicate with others.”

Some systems use a push-to-talk (PTT) button; others use a voice-activated (VOX) system for two-way communication. The microphones used in these systems will only pick up sounds in the 60 to 70 dB(a) range, effectively transmitting human voice without much of the background noise on the jobsite.

The self-contained two-way radio headsets offer up to a two-mile operating range, but can’t offer the extended distance of a 5-watt radio, says Cimino.

Not a cure-all
Although the active-listening HPDs can knock down dangerous sound levels for users, Westerdal cautions they are not a cure-all.

Models under development will allow users to “fine-tune” the high- and low-frequency cut-off settings to better tune the unit to the jobsite.

On jobsites with a wide variety of sounds, these units may be only marginally helpful, which could be negated by the cost of the units, which range from $60 for FM radio receiver units to up to $500 for two-way radio units.

This article was published in the September/October 2002 issue of Contractor Tools and Supplies magazine.

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