Every 15 minutes, temperature sensors built by WNYC and its partners in the Harlem Heat Project have been recording temperatures inside 30 Harlem apartments. All day. All night.

We wanted you to hear what the heat in Harlem sounds like on an average summer day. So the WNYC Data News team looked at the average heat index throughout the day and turned each feels-like temperature into a musical note. We then condensed a full 24 hours of readings into 20-second songs: one for the outdoor temperature, and one for the indoor temperature.

To hear them, click on the "Outside" or "Inside" labels above. (Or the "Remix!" button, which is a combo.) 

We found that the heat index inside our participants' homes regularly stay higher than 80 degrees, for days and nights on end, not even cooling off the way it does outside when the sun goes down. The National Weather Service says prolonged exposure to a heat index of 80 degrees or more can lead to fatigue. 

This week in the Harlem Heat Project, we explore how people use air conditioning to keep cool. By doing so, they often exacerbate global warming because of the carbon emissions created by the excess energy consumption. To hear that story, click the "Listen" button above.