Sound & Sight Perception

The New York Times had an article about a device some guy in the UK came up called the Mosquito which a noise-based theft deterent device. Apparently, the noise this gadget emits cannot be heard by most people over 30, but manifests as a really annoying pulsing buzz at 75 db for us young-uns. Now why would someone want to target the youth of today? To stop them from shoplifting, loitering, or generally having any fun or freedom away from home. I find this a fascinating application of the subjectively of everyone's perceptions. We are always told, the human ear can't hear below 20hz or above 20k give or take a bit. Now I suppose this must be based on youthful, perceptive brain-microphones - since the older we get, the more we need hearing augmentation of some kind. Same applies for eye-sight. Usually in the form of sharpness, or focus. But does eyesight degrade throughout life in terms of color vibrancy, or range of color perception? Obviously, all forms of colorblindness are the most obvious types of sight limitation, but can/does this happen to us all to a more limited extent?