Masking music's drawbacks?

What are the many inputs and outputs that a designer must consider?

What impact does the outside environment have on the design of software?

Background Once upon a time, in a certain medieval village, a group of mysterious strangers appeared in jeans and T-shirts. The strangers managed to learn enough Old English to explain that they had been enjoying their favourite pastime – belting out tunes at a karaoke party – when they saw a blinding flash and heard a thunderous roar, lost consciousness, and found themselves transported back in time without any explanation. The villagers were most interested in the strangers’ wide-ranging knowledge of popular songs from the future. They understood that the strangers belonged to some sort of bard class. The villagers were also party animals, and had a feast every night. The bards agreed to come to some of the parties and sing one Billboard Top 40 song whenever they did. When they weren’t there, the villagers would sing these songs to each other, reverently, knowing that they held clues to the future of their world. The more they learned, the more they were able to share, and some were…

What heuristics can you use to make your system's design better?

What are the many inputs and outputs that a designer must consider?