# Density — Sound Terrain

February 3, 2020

### The US is big

I’m sure you already know this, but The United States of America is a huge place. And I’m sure you also know that the population is not evenly distributed. So that’s not interesting.

What is interesting is experiencing that distribution in a way that you probably haven’t before.

Imagine a physical topographical map of the entire US on a table. Now imagine lowering your head so that your eyes are level with the table and you’re looking at it from the South. This is the concept behind what you’re hearing. The difference is that instead of terrain, we’re looking at the density of where our customers are.

Let’s look at the data. We’re about to see where our deliveries happen grouped by longitude, West is on the left, East is on the right. See if you can identify the different US cities by just looking at this chart. Thinking of the whole country just by longitude probably isn’t the way you’re used to looking at it.

Give it a try!

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No cheating!

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Check out how you did:

### The Data

What we’re seeing here is a measure of our customers on a logarithmic scale by longitude.

We’re scanning through it from West to East, so you can think of that graph as the “score” for this piece.

### What You’re Hearing

We’ve got a static note played on a synthesizer sustained throughout the entire piece. It definitely doesn’t sound static though.

The data is controlling a number of parameters all at once:

• Level of sub-bass
• Overdrive
• Reverb level
• Delay level
• Delay feedback
• Chorus level
• Frequency modulation amount on filter cutoff

Essentially, the more full, distorted, and erratic the sound becomes, the more customers are concentrated at that longitude.

### How it Works

I made a simplified tutorial on how to create these from start to finish. Check out the Colab notebook if you want to make one yourself.

This is another very basic one that can be created with just the sample notebook above. We’ve just gone one note that is constantly sustained, and the data that created the chart you saw above was scaled to integers between 0–127 and are put into a MIDI Control Change (CC) track.

Then I bring it into my DAW (REAPER), open up a synth plugin (in this case I’m using Waves Element 2.0), and then I map that one MIDI CC track to multiple parameters.

### Conclusion

Geography is not always intuitive. Put these in order from West to East: Los Angeles, Reno, San Francisco, Seattle. Or for you East Coast people, Charlotte, Cleveland, Miami, and Pittsburgh.

I’m sure a bunch of you will get it right, but the point is you really have to think about it and be pretty damn good at geography to nail it. (If you’re curious: San Francisco, Seattle, Reno, LA, and Cleveland, Charlotte, Miami, Pittsburgh)

I think it’s always a good thing to put something you think you understand into a new context that makes you look at something in a new way. Looking at where our customers are this way isn’t going to reshape how we think about the company per se, but it sure sounds neat.

Postmates is always looking for creative data-focused people to join our team. If you want to make things like this, check out https://careers.postmates.com/ and say that Alex sent you.

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