Personal reverse alarm

At the end of a long and wearying shopping trip, I lose a large amount of my sense of coordination, personal space, and all those other crazy there-are-other- people-in-the-world skills.

When navigating my way through yet another full shop trying to keep an eye on two equally bored kids and appease my wife who has long since sensed my lack of commitment to the matter at hand, I tend to back up without checking who, or what is behind me. Frequently. This can extend the shopping trip even more.

The basic, slightly arrogant version of my proposed solution is a gyroscope equipped alarm, that senses when you are moving backwards and emits noises similar to those UPS vans: "This - person - is - reversing. This - person - is - reversing."

The slightly more sensitive version, which is more useful in a china shop, too, would have a set of those reverse sensors they have on modern car bumpers. Beeps close to your ear increase in frequency the closer you get to an object behind you.

I find my responsiveness to stimuli in these situation tends to deteriorate substantially, so maybe a combination of the two solutions might be best.