Hearing aids have come a long way. Centuries ago they were little more than straight trumpets — think the kind of horn an angel might sport — that you stuck in your ear to make everything louder. Today they are microcomputers with far more processing power than the Apollo spacecraft carried onboard.

One of the key events in the development of modern hearing aids was Alexander Graham Bell’s new gizmo, the telephone (and the subsequent development of the carbon microphone). A relatively small machine using electrical currents to transport sound — and the subsequent development a way to amplify those signals — was the first step.

But relatively is a key word in this process.

The first commercially marketed hearing aid was Western Electric Company’s Vactuphone, which sold for over $100 in 1921 (about $1,500 in current dollars). It was the size of a small suitcase, heavy, and anyone who wanted to talk had to come to you, not the other way around.

Things got relatively smaller and lighter in the following decades, but even “portable” hearing aids were a chore. It wasn’t until the invention of the transistor in 1948 that the possibility of a hearing aid that could be practical in everyday settings became feasible.

The next few decades — into the 1990s — saw transistor-based technology get better and better and increasingly integrated into everyday life. But since the digital revolution hit, hearing aids have become ever more unobtrusive while simultaneously becoming far more powerful.

Today’s models are small, durable, and not only able to counteract most forms of hearing loss, but also connect wirelessly with other digital devices such as smartphones, computers, and home entertainment components. A long way from sticking a rudimentary musical instrument in the ear.