Research sponsored by the Center for Operator Performance (COP) reveals that some alarm tones standard on distributed control systems (DCS) may be undetectable by older operators who have age-induced hearing loss, particularly in the presence of control room noise. A pilot study by Drs. John Casali and Kichol Lee of Virginia Tech University conducted spectral analyses of alarm sounds in two refinery control rooms. Certain alarm sounds standard on DCS systems (e.g., chime) are predominately in the same frequency range that is affected by age-induced hearing loss. The result is that older operators may not be able to “hear” alarms that use these sounds. This is particularly problematic if operators are able to adjust alarm volumes, where the previous shift operator may have reduced the volume, thereby making detection even 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.
The Center for Operator Performance is a collaboration of operating companies and DCS suppliers that conduct research focused on ways to improve operator performance. Operating companies include: Chevron (ChevronPhillips), Koch Industries (Flint Hills Resources, Invista Chemical, Georgia Pacific), Citgo and Nova Chemicals (Borealis). The DCS suppliers are Emerson and Yokogawa (KBC).
For more information, visit: www.operatorperformance.org