Age-induced hearing loss may make certain alarms undetectable for older operators

The Center for Operator Performance (COP) has revealed research that indicates some alarm tones standard on Distributed Control Systems (DCS) may be undetectable by older operators who have age-induced hearing loss, and particularly so in the presence of control room noise. A pilot study by Dr. John Casali and Dr. Kichol Lee of Virginia Tech University conducted spectral analyses of alarm sounds in two refinery control rooms. Certain alarm sounds standard on DCS systems, like a chime, are predominately in the same frequency range that is affected by age-induced hearing loss.

According to COP, this means that older operators may be unable to “hear” alarms that use these sounds, which problematic if operators are able to adjust alarm volumes, where the previous shift operator may have reduced the volume, making detection more difficult.

A more detailed study to determine optimal alarm sounds is being planned. The study will provide recommendations not only to accommodate the age-induced and noise-induced hearing loss problems, but also encoding alarm priorities in multi-console control rooms.