At the Baton Rouge Fire Department, voice communication by radio begins at the microphone and ends at the speaker or earphone — same as anywhere else. That much is simple. Firefighting apparatus, such as pumpers and tankers, make loud noise that could induce hearing loss besides interfering with communications.
“Communications is a vital part of firefighting. We experiment almost daily to develop better ways of using microphones of all kinds and headsets,” said Ed Smith, chief of the department's Special Services Division.
For comfort, hearing protection and an improved ability to hear from an earphone when noise is loud, a double-ear headset with gel- or water-filled ear cups that mold to the ear work well, said Carolyn Servidio, president of RadioMate, a headset manufacturer in Concord, Calif.
But firefighters working the pumpers for the Baton Rouge, La., fire department prefer single-ear headsets.
“When our firefighters are standing next to the apparatus, they want the noise coming in, so they can be aware of what's going on. They won't wear double-ear headsets that reduce their peripheral hearing,” Smith said.
Although a running pump makes a lot of noise, Smith said it is not so loud that the firefighters worry about possible hearing loss when on an emergency response. He said that when operators might test a pump for 30 to 40 minutes at a time, though, they wear hearing protection.
Paul Mills, RadioMate's vice president, said that OSHA requires a certain amount of noise reduction because of the siren. For example, the National Institute of Occupational Safety and Health puts a level of 85 dB as the dividing line between sound that doesn't cause hearing loss and sound that may. A worker near a siren could be exposed to sound as loud as 120 dB.
“The dual-ear headset protects hearing while allowing communications among users on the rig while it's running. It offers protection from loud and abrupt noises such as sirens and air horns,” Mills said.
Servidio added that headsets supplied with a slotted ear cup for hearing protection allows the wearer to hear some ambient noise.
A second type of headset worn inside helmets serves firefighters working at a distance from the apparatus. With helmet headsets, Smith said the biggest problem is overcoming background noise in both directions.
“Clarity always is a problem. We try throat microphones and bone-conductive microphones. Most of our studies indicate that background noise is the biggest hindrance to the helmet microphone,” Smith said.
The Baton Rouge Fire Department also wants headsets with interchangeability among helmets. The department uses a headset with a cloth strap that goes over the top of the head and drops down around the ear.
With a headset inside the helmet, Smith said his department sometimes uses a pad-like switch positioned in the firefighter's armpit where it is activated either by pushing it with the opposite hand or by squeezing it with the arm. “It helps with the background noise and avoids the risk of a speaker mic picking up everything that's said on the scene that doesn't need to reach the public through scanners. Things can get hectic, and people can shout something, and you have to control that function,” he said.
Every truck has two portable radios with speaker mics. Firefighters normally carry them in a pocket made for the purpose. Smith said that the problem with those units was that “you have to have hands available to push the button to talk. And you're wearing an air pack and mask, everything sounds garbled, and you have to talk back through the mask.”
Otto Communications in Carpentersville, Ill., designed its Genesis speaker mic with a large, snap-action push-to-talk switch that has positive tactile feedback, yet resists accidental actuation. The large diameter button allows a firefighter to actuate it with or without protective clothing such as fire gloves.
A dual grill seals the speaker mic from high-pressure water and submersion in 1 meter of water for 31 minutes (IP68 standard). A removable front grill and a washable speaker cavity area lets users wash away accumulated dust, dirt and other debris. An optional debris screen that fits beneath the front grill resists extreme conditions.
With an optional watertight accessory jack, the speaker mic supports skull microphones, throat microphones and headsets that can be used with a breathing apparatus.
Smith said that in firefighting, a hand-operated radio conflicts with the manual operation of hoses and axes. “There's a deficiency in having to use speaker mics, but we do use them,” he said.
When it comes to radio communications, “the more information you can get out to the command post and to the firefighters, the more positive the results. That's always a goal we try to achieve,” Smith said.
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