What makes the click when you take a photo on your phone?

Film cameras and many digital cameras set how long light reaches the sensor with a thin curtain in front of it that opens and closes. When that curtain moved, it made a short, crisp sound.

Most phone cameras have no such curtain. The sensor electronically controls when it starts and stops taking in light, and with no moving parts it would make no sound at all. The idea that a tiny door shuts behind the lens every time is a common misconception. The brief flicker on the screen when you take a shot is the same kind of confirmation signal.

The click is a sound effect that plays briefly through the speaker only at the moment you shoot. It isn't saved in the photo file, and taking a picture silently doesn't change its quality.

The sound still earns its place. Before your eyes check, your ears tell you whether your finger really pressed the screen and the photo was taken. Imitating the familiar film camera sound makes that signal easy to recognize right away.

In many countries, switching to silent mode turns off the click too. Apple's help pages say you can mute the shutter sound with silent mode, and add that in some countries and regions you can't.

Korea and Japan are the best-known examples. In 2004, to discourage illegal filming, Korea's Telecommunications Technology Association created a standard requiring a 60 to 68 dB shutter sound. It isn't a law, but carriers and manufacturers follow it, so it became the default in practice. Japan has also included the sound under a voluntary standard among its mobile carriers.

So a phone bought in Korea clicks even in silent mode. In quiet places like a library, a concert hall, or a room where a baby is sleeping, glancing around before you shoot makes things easier for everyone.

Even the same model can have different shutter sound settings depending on the country where it was sold or the network it connects to. The reason phones sound different lies more in each market's standards than in the hardware.