To minimize training and enhance crew performance, Space Station Freedom will use the same auditory alarms that are in use for the Orbiter ( i.e. fire/smoke, rapid delta pressure, master, and systems management alarms). However, it has been determined that an additional toxic -atmosphere alarm is required for Space Station Freedom. The purpose of this study was to select an auditory toxic-atmosphere alarm for Space Station Freedom. Four final toxic alarm candidates were selected to be tested based upon expected performance indicated by previous research, compatibility with existing Orbiter alarms, and human hearing characteristics. The candidate toxic atmosphere and the Orbiter alarms were tested to determine how well they could be remembered and discriminated. All 100 subjects received the four Orbiter alarms. Each group of 25 of these subjects received one candidate toxic alarm. The results of the comparisons between the candidate toxic alarms indicated that the “Chirp” alarm ranked first for both response times and errors. The next evaluation looked at how the Orbiter alarms compared with the “Chirp” toxic alarm. The results indicated that “Chirp” toxic alarm had the lowest mean response time and the lowest mean errors when compared to the Orbiter alarms. These results indicate that the “Chirp” alarm most consistently ranked highest of the four candidate toxic alarms tested and that this alarm also elicited competitive performance, in terms of response times and correct identifications, when compared with the existing Orbiter alarms.
