Congruency effects with dynamic auditory stimuli: design implications

Since pitch is a commonly varied parameter in auditory displays, we investigated whether it is possible to attend to relative pitch while ignoring changes in pitch, and whether changes in pitch could be assessed independently of the overall pitch of a dynamic auditory stimulus. Stimuli were defined as either congruent (e.g., high pitch stimulus that became higher in pitch) or incongruent (e.g., high pitch stimulus that became lower in pitch). In this experiment, faster responses to congruent stimuli indicated a failure of selective attention. This effect was uniform for pitch judgments with all stimuli, but varied with the overall pitch for pitch-change judgments. The performance difference between congruent and incongruent trials was greatest for the extreme (high or low) stimuli. Moreover, pitch information intruded more into responses to pitch change than vice versa. Auditory display designers can use congruent stimuli to help distinguish between high and low pitches. If pitch change is the important dimension, designers should restrict the range over which stimulus pitches vary.