iPhone 4 goes far in music playback time

CNET Labs has returned the official iPhone 4 battery results for music playback time. With 3G turned on, we managed an impressive 59.02 hours in our longest test. That more than beats Apple's promised time of 40 hours for audio playback. As a reminder, we also surpassed Apple's rated talk times in the CNET Labs test last month.

When we conduct our music playback battery life test, we start with a fully charged phone. The display is set to a brightness level of 50 percent, and the backlight is set to turn off after 10 seconds. All phones are set to the same volume level, which we measure electronically to ensure fairness and consistency in testing. If the phone includes an EQ setting, we set it to "flat." We play a group of repeating audio files and record the amount of time that passes until the phone's battery drains and it shuts off.

Times in chart are in hours