How Brian Eno works.

A history of the cell phone ringtone.

Many recent hip-hop songs make terrific ringtones because they already sound like ringtones. The polyphonic and master-tone versions of “Goodies,” by Ciara, for example, are nearly identical. Ringtones, it turns out, are inherently pop: musical expression distilled to one urgent, representative hook. As ringtones become part of our environment, they could push pop music toward new levels of concision, repetition, and catchiness.

On the producer Timbaland, then best known for collaborations with Missy Elliott, Aaliyah, and Ginuwine.