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This is 99% Invisible. I'm Roman Mars.

Here at the San Francisco main library, and that is Dennis Paletti.

If you walk into the library, there's a five-story atrium.

He's an acoustic designer, and it also is very hard and reflective with all of the plaster, concrete, reflective materials.

Companies hire him to make their buildings and boardrooms and cathedrals and public spaces sound better.

One in early scheme, the architect had the main information desk right in the middle of that floor plant in the center of that five-story atrium.

The commotion that would go on, it would be disastrous for the people who had to work there to try to hear the visitors coming in asking for things and trying to communicate.

One of the things we recommend was to just tuck that information desk off of the atrium and tuck it under some of the mezzanines.

Pretty simple, pretty minor, but to me just made such an improvement, I always liked that solution.

But that's smart and simple choice to tuck the information desk over to the left side.

Patrons and librarians could actually hear each other created this wide open circular entryway, and no one really knows how to walk across it without bumping into someone else.

So this beautiful $140 million building has an added feature that certainly was not on the architect's plans.

It's a hack, a jankety, retractable movie theater style velvet rope partition that helps create the proper traffic flow.

And right there, 15 feet apart from one another, a minor triumph and a minor failure of design.

In the epic of Gilgamesh, the gods get so infuriated with the noisiness of their human neighbors that they send a flood to wipe us all out.

And when you walk around the city, it's pretty easy to slide with the gods in that scenario.

What is noise?

Noise is very simply as unwanted sound. It used to be called environmental noise. But in recent years, people are beginning to get interested in looking at a city's environment as something unique to that city.

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