Looming sounds as auditory warnings: Uses for enhancing visual contrast sensitivity?

Looming sounds have been shown to influence visual perception, suggesting they may make effective auditory warning tones for use with visual tasks. To explore the use of looming sounds as warning signals and to determine whether the strength of a looming sound will impact its effectiveness, we tested five looming sounds with different amplitude increases as warning tones in a contrast sensitivity task where participants made judgements concerning the orientation of low-contrast sinusoidal gratings. Reaction time, accuracy, and contrast threshold were measured for each sound condition. Our results indicate that accuracy was higher and reaction time was faster when a sound was present compared to when no sound was present, and contrast threshold was significantly lowered in sound trials compared to silent trials. However, there was no difference in accuracy, reaction time, or contrast threshold by strength of looming. These results suggest that while auditory warning sounds do enhance performance on a basic visual task, the benefit was not unique to looming sounds. This experiment will help inform the design of warnings by providing insight into the underlying effects of looming sounds on visual performance.