The researchers found that if there was no air puff, participants misheard "pa" for "ba" and "ta" for "da" 30 to 40 percent of the time. The accuracy improved 10 to 20 percent when an air puff over the hand or neck accompanied "pa" and "ta." No improvement occurred, however, if an air puff was sent through the tube in the ear, suggesting that the participants were not simply hearing the airflow.
The opposite effect was observed when the participants received an air puff with the inappropriate sounds— "ba" and "da." While subjects correctly identified these sounds in about 80 percent of cases when played without the release of air, the accuracy decreased by about 10 percent if the sounds were accompanied by puffs of air.
Most of the volunteers were not consciously aware of the puffs of air. Link