The sound is controlled by the App on your smartphone.
If you tap on the ICON photo of your model tile in the App, the Bluetooth transceiver in your phone silently "pings" that tile tracker device. The app will show green rings adding multiple concentric rings as you gain closer proximity to your tile. The tile remains silent. Useful, just to verify your stuff is within range. Since it is quiet, this ping mode uses less power from the tile's battery (no speaker), assuring a life of >1yr.
If you want to find your tile audibly (lost car keys that you know must be somewhere inside the house), instead, tap on the GREEN "find" button in the App. You can remotely control whether the volume is either on or off on your tile. This is helpful if you desire "stealth mode", which again, is more battery efficient. It is useful to not audibly tip-off thieves, that the device is in the car, so it can do its work and rat-out their location. Having one hidden in your car, is akin to having a poor-man's LoJack type device, without the related cost.
When the battery eventually gets depleted (>1yr), your tile will communicate this to you thru your App. You can then send it in the free provided shipping envelope to obtain a replacement, via the ReUp program.