It's time to talk about one of the most common - and annoying - sounds in the world: Beeping. Which we hear every time we use the microwave, get a text, or hear a trash truck backing up. But why do so many things use such an annoying sound? Robert White is a professor of mechanical engineering at Tufts University. And he says that beeps are cheap. In other words, making a beep requires very little electricity or computing power, and can be created using small, inexpensive speakers. But why are they so irritating? Shouldn't we be used to them by now? Michael Schutz is a researcher at McMaster University's Institute for Music and the Mind. And he says it's hard for us to accept the beep because our brains are wired to hear sounds produced in the natural world, like music or birdsong, in which notes fade out. But flat, constant tones - like repeating beeps - fall into the same mental category as car crashes and other unexpected sounds that create stress. The researchers equate a flat beep sound to a car driving 60 miles per hour then suddenly hitting a wall, as opposed to gradually slowing to a stop. Of course, we need some beeps to jar us into paying attention. You might get hit by a truck if its back-up signal played Mozart. And, your smoke alarm's supposed to get your adrenaline flowing. But, when it comes to our gadgets, some tech companies are giving people the option of hearing more natural sounds instead of flat, harsh beeps. And it pays off. In a study, people were alerted to a missed cell phone call by either four flat beeps - or notes that faded out. And when asked which phone they'd buy, nearly 90-percent of the people tested preferred the phone that used the natural tones.