Twitch has gone from streaming video to streaming audio. Don’t worry, this isn’t a bold new direction. This is just another option for users of the Twitch iOS app to enjoy content. With the newest update, you have the option of only listening to audio.
You can also put your phone to sleep without stopping playback. Controls such as volume, pause, rewind and fast forward can all be accessed from the lockscreen. If you want to take things a step forward, you can go into your device’s settings and set up the app to default to audio whenever you lock your device.
I see this audio option as being particularly useful for professional gaming tournaments that have commentators. It shouldn’t be any different than listening to a basketball or baseball game on the radio. Assuming the commentators can do a good job of painting a visual picture, the listeners shouldn’t feel like they’re missing out on the action.
Source [Twitch Blog]