Ailsa Chang

The question of how Billboard determines the most popular music in the country has gotten a lot harder in the digital age. It used to be a simple question of which album sold the most physical copies, but now Billboard needs to consider things like Spotify plays and mp3 downloads. Starting Jan. 3, it will also include YouTube streams.

NPR's Ailsa Chang talks to Chris Molanphy, a chart analyst and pop critic at Slate, about the significance of this change. Listen at the audio link and read on for an edited version of their conversation.

Two witnesses testified during the last scheduled day of public impeachment hearings on Thursday. Fiona Hill, a former National Security Council official, and David Holmes, a political counselor in the U.S. Embassy in Ukraine, spoke in front of the House Intelligence Committee — wrapping up two weeks of public and closed-door testimonies to Congress about President Trump's actions in the Ukraine affair. Click the audio link to listen to a special broadcast of NPR hosts and reporters offering analysis on the significant moments of the day.

Four witnesses testified before the House Intelligence Committee on Tuesday in the impeachment inquiry into President Trump: Jennifer Williams, an aide to Vice President Pence; Lt. Col. Alexander Vindman, a National Security Council adviser; Kurt Volker, the former U.S. special envoy to Ukraine; and Tim Morrison, a former National Security Council adviser. Click the audio link to listen to a special broadcast of NPR hosts and reporters offering analysis on the significant moments of the day.

The former U.S. Ambassador to Ukraine, Marie Yovanovitch, testified in front of the House Intelligence Committee on Friday in the public phase of the impeachment inquiry. Click the audio link to listen to a special broadcast of NPR hosts and reporters offering analysis on the significant moments of the day.