The most mundane things that you use every day (think post it notes, rubber bands, concrete) often have fascinating stories behind them.
In fact, people often only notice how something's designed when it goes wrong. But the process of discovery, testing and prototyping anything, no matter how ordinary, is full of pitfalls and the occasional exhilarating breakthrough.
Hearing Aid
Simply cupping your hand around your ear can improve your hearing by five per cent. By reflecting more sound waves into your ear, noises are amplified. It's the principle upon which ear trumpets of the Victorian age worked. It's also the basis upon which modern behind-the-ear hearing aids work. Sound is picked up by a microphone and transformed into electrical signals. These are then boosted before being turned back into sound, which is output through a small speaker placed inside the ear canal. Marconi made the first 'portable' electronic hearing aid in 1923, weighing 7kg. Although the audio components were relatively small, the battery needed to power them wasn't. The development of smaller batteries and electrical transistors to replace bulky valve amplifiers meant that in the 1950s hearing aids were truly portable, forerunners of those available today.
Space Shuttle