As a baseline starting point, each test bug was subjected to a horn blast and noted that all would jump.
As the research progressed, the legs of each grasshopper were removed one at a time and the test bug again subjected to a horn blast, noting that the test bugs would jump at the sound.
After the last leg of each test bug was removed and again subjected to the horn blast, the test bugs did not move and remained motionless. The testing continued for several more months to verify the results.
It was then determined that if you remove all the legs of a grasshopper, they go deaf.