Many years ago I wrote some software for use on a laptop by biologists studying migrating birds of prey. The laptop collected several key data items for each group of birds that was observed. The input was specificly designed to be easy to enter with one hand and without looking at the keyboard. This is because the person using the software is likely holding a pair of binoculars and staring at the birds trying to determine what values to record before they fly too far away (or one gets lured in to be measured and tagged).

The problem with this is that if they make a mistake, they likely won't notice until it is too late.

So the software played middle C when the first value was entered correctly. Then it played D when the second value was entered correctly. This chromatic scale continued until the final value was entered correctly when it played a major third progression (C E G).

They were happy with the software so I got to spend several nights on a desert mountain top watching birds and even helping to capture, measure, and tag a few (and fixing any problems with the software). (Capturing migrating birds of prey is astonishingly like fishing, only up-side-down and less boring because you can clearly see who you are trying to fool and how they are reacting to the bait.)

The other civilians (a.k.a. non-biologists) at camp were fond of telling me how lucky I was because they had each paid quite a bit of money in order to have the privilege of volunteering to help.

I didn't sleep much, despite the kind donation of a couple self-inflating foam sleeping pads (I think each was only about 1/2" thick). But it was a great trip, mostly because all of the biologists and civilians were such good company. I think having had to sacrifice in order to have the privilege of being there combined with knowing that if anyone got sick or hurt helicopters would have to get involved made for unusually good interpersonal relationships.