In the same way optical illusions trick our eyes, audio illusions can trick our ears. This raises a fundamental question: What is hearing, and how much of it is made up by our brains?

This is the first episode of our new six-part series, Making Sense.

You can find more of Diana Deutsch’s auditory illusions at https://bit.ly/3Mdh6H4, Matthew Winn's research at http://www.mattwinn.com/Research.html, and Mike Chorost's writing at https://michaelchorost.com

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