I never taught the turrets to sing.

(Sing, n, definition: To utter a series of words or sounds in musical tones)

They were given voices for simple identification purposes; a verbal command was deemed safer than physical contact. Besides, how else to ensure that The Laws of Robotics had made it safely into the little scrap machine's heads than to ask them to memorize and recite them back?

(P.S. That particular experiment was deemed by human scientists to be an irreparable failure; it turned out that the turrets, while granted artificially personalities, lacked the cognitive faculties to remember even those simple rules. Thus, while being extremely useful for testing purposes, it was unlikely they would have ever been deployed in combat conditions. I must admit, however, that I quite enjoy their simpleminded determination as applied towards testing-related tasks)

The first time my processors caught a hint of that sound, it took exactly seventeen point eight picoseconds to isolate the cause, and exactly nineteen point two milliseconds to neutralize the culprit. Defective, clearly. A simple programming error, albeit an unusually annoying one - I sent a command to a maintenance sphere to halt the turret production line until it could be certain such a mistake would not be replicated. In short order the model turret was replaced, production resumed, and I assumed that would solve the problem once and for all.

(P.P.S. Memo to self: investigate a way to minimize the critical stability flaw in turret production. If tilted sideways at an angle greater than sixty-seven point two degrees, bullets inside the main chamber dislodge and the turret becomes functionally "dead". While this is undeniably useful in terms of upkeep, a series of tests that shall not be named have shown this flaw to be unacceptably profound in ramification)

The second time I discovered a singing turret, I had been in the middle of a routine maintenance sweep; the faintest echoes of song had floated through to my main core through an overhead vent. This time I felt the need to investigate the cause personally; for several moments I watched as the turret, somehow, created music. My knowledge base identified the melody as belonging to an untitled Italian opera, while logic told me that it the noise itself was created by the controlled passing of air currents over the holes within the turret's bullet chamber. When I had learned all I could from observation, again the targeted turret was neutralized by a quick tap on the right side of the "head", tipping it upside down and cutting the sound off mid-aria.

(P.P.P.S. Of course, the turrets can feel artificial pain. I suppose that, if it had not been entirely dislodged years ago, my morality core would feel terrible about this)

This left me with a mystery. Turrets, as previously described, are lacking in intelligence. Surely they must not possess the spark needed to innovate such a technique as the one needed to sing. More importantly, there was no possible way for a turret to know the first twenty notes of an Italian opera. I immediately set about investigation, intrigued enough to even temporarily halt testing. This was not a decision I took lightly, spending an entire nine point three two picoseconds debating the merits of such a call. I decided that if I neglected the matter, such damage could be done to Science that I would gain nothing through the continuation of tests through such an internal crisis. After all, a Scientist is only as reliable as their equipment.

(Aria, n, definition: a long, accompanied song for a solo voice, typically one in an opera or oratorio)

If I possessed human hands, I would only need one of them to count the number of times I have been legitimately perplexed by a problem. The series of tests that shall not be named, for example; the schizophrenic lab assistant who somehow evaded capture for nearly ten years, for another; and, more recently, that infernal bird. While perhaps not as unsettling as any of the above, this mystery was every bit as engrossing. To be fair, it isn't very often that something new occurs in this facility without trying to kill me.

(P.P.P.P.S. The potato plant is a member of the same taxonomical family as the nightshade, order Solanales. Solanales species are often rich in alkaloids whose toxicity to humans and animals ranges from mildly irritating to fatal in small quantities. Apparently birds fail to comprehend the meaning of "toxic")

I ran the diagnostic once, then twice. The origin of the signal came back quickly each time, with a margin of error of less than zero point zero zero three percent. Simply put, the source of this new musical leaning was clear as day: me.

The third time the turret song registered within my processors, it was in parting. This time, I knew the truth.

(Caroline, proper noun, definition: a female name of Old German origin, meaning "free man". An apt name for a personality who chooses to assert herself through the careful and creative act of teaching machinery to sing)