How the piano allowed for dynamic volume control

HostMost of us have a piano in the house or at least know the sound of one. It's the go-to tool for almost every kind of music. We take it for granted that a player can sit down and make the music whisper or roar just by changing how they touch the keys.

HostBut for a long time, keyboard players were stuck in a world where everything stayed at the same volume. How did a change in the way these machines were built finally let musicians play with so much more feeling?

GuestIt really comes down to what's happening inside the box when you press a key. Before the piano came along, the main keyboard was the harpsichord. If you looked under the lid, you would see rows of strings, but they weren't being hit. Instead, there was a tiny little pick, often made from a bird feather, that would reach out and pluck the string. It's a bit like a tiny guitar player sitting inside the instrument. The problem is that a pluck is a pluck. No matter how fast or hard you hit the key, that little piece of quill is going to pull the string with the same amount of strength every single time.

HostSo the music always stayed at one level. It sounds like it would be like typing on a computer. It doesn't matter how hard I hit the letter A, it always looks the same on the screen.

GuestThat's a great way to think about it. You could've two different rows of keys that were set to different volumes, but you couldn't change the sound in the middle of a song. You couldn't start soft and slowly get louder. It was more like a light switch than a dial. Then, right around the year seventeen hundred, a man in Italy named Bartolomeo Cristofori decided he wanted something better. He wanted an instrument that could do both soft and loud. In fact, that's where the name comes from. The full name was the soft-loud, or the pianoforte. He threw out the feathers and the plucking and replaced them with hammers.

HostBut people had been hitting strings with hammers for a long time. If you take a stick and hit a string, you get a sound. Why did it take a genius in Italy to figure out how to put that into a keyboard?

GuestBecause the physics of hitting a string is much harder than plucking one. When you pluck a string, the pick moves past it and the string is free to shake and make noise. But if you hit a string with a hammer and the hammer stays there, it kills the sound instantly. It just goes thud. To make it work, you need a very tricky bit of engineering called an escapement. It's a part that lets the hammer fly at the string, hit it, and then jump back immediately, even if your finger is still holding the key down. This lets the string keep shaking. Without that little trick of the hammer letting go at the last second, the piano would just be a box of muted thumps.

HostThat sounds like a lot of extra moving parts just to get a little bit of volume. I have to wonder if it was really worth the trouble. I mean, people like Bach wrote some of the most beautiful music ever for the harpsichord. Was the lack of volume really that big of a deal?

GuestIt changed the very soul of the music. In the old days, if a composer wanted to show a big emotion, they had to use lots of notes. They would write fast runs or big chords to fill the air. But with the piano, you could suddenly have a melody that stood out because it was louder than the notes around it. It let the music breathe more like a human voice. A singer can swell on a single note or trail off into a sigh. The piano finally let a keyboard player do that. It turned the instrument from a ticking clock into something that felt alive.

HostI still find it hard to believe that plucking was that limited. Could you not just use a thicker pick or pull the string harder to get more noise?

GuestYou can only pull a string so far before it snaps or sounds out of tune. Hitting a string with a hammer is a totally different beast because you can put the weight of your whole arm into it. As the piano grew, the frames had to be made of heavy iron just to hold the tension of the thicker strings that those hammers were hitting. A harpsichord is a delicate piece of furniture, but a piano is a heavy machine built to handle a lot of force. That force is what gives us that huge range of sound. You can have the hammer barely graze the wire for a sound like a ghost, or you can slam it down to fill a whole concert hall.

HostIt sounds like the piano really took the power away from the machine and gave it back to the person sitting at the bench.

GuestIt made the player the boss of the sound in a way they never were before. Instead of just picking the right notes at the right time, they had to think about the weight of their fingers and the mood of the room. It made every performance unique because no two people hit those keys with the exact same strength. The invention of that little leaping hammer gave composers a whole new way to talk to us.

HostThose hammers did more than just strike wire; they let the music finally say what words could not.

GuestThe piano turned the keyboard from a set of buttons into a tool that could capture the tiny shifts in how a person feels.

HostThe next time I hear a song fade into a whisper, I'll think of that first Italian builder and his leaping hammers.