"Very well. Now, are you watching what Mr. Oak is doing?"
"Yes, sir."
I picked up a small ball-peen hammer and hit the speaker—not too gently—at just the right place.
"Did you see that, McGuire?" I asked.
"Yes, sir. I saw it." His voice sounded hoarse, muffled, and whispery coming through the damaged speaker.
"Do you see what sudden damage can do to speaking apparatus?"
"I must test," McGuire said, an almost hesitant note in his new voice. He spent fifteen seconds or so saying a series of nonsense syllables that are used as a test for a robot's speaking apparatus. They contain every sound used in English.
When that was over, he said: "The damage inflicted has radically changed the basic patterns of the voice. If an equivalent amount of damage was done to Mr. Oak's vocal apparatus, then the voice which has been speaking must belong to Mr. Oak."
"You saw the damage being done in each case," I said quickly. "You also see that it is the source of the voice that becomes important when the pattern has changed."
"Yes, Mr. Oak. I see that."