What sound(s) do you hear when the camera takes a photo? You should a distinct series of clicks as the mirror moves up, the shutter fires, and mirror moves back to its resting position.
The shutter button has a “double action” built into it. You can “half press” the button, which causes it to AF, Auto Focus. You can then “fully press” the shutter button to actually take the photo.
In some shooting modes, the flash my pop open and flash when you “half press” the shutter to focus. The light that flashes is called a Focus Assist Beam. It does not make much noise.
When you fully press the shutter after you have locked focus, you should hear the series of clicking noises I described earlier.