From the Now Playing screen, tap the cover.
The email, 30-second repeat, and playback speed controls appear along with the scrubber bar. You can see elapsed time, remaining time, and the episode or chapter number.
The scrubber bar lets you skip to any point along the timeline. You can adjust the scrub rate from high-speed to fine by sliding your finger down as you drag the playhead along the scrubber bar.

Tap
.
Drag the playhead along the scrubber bar. Slide your finger down to adjust the scrub rate. The scrub rate becomes slower the farther down you slide your finger.
Tap
.
Tap
. Tap again to change the speed.
= Play at double speed.
= Play at half speed.
= Play at normal speed.