For audiophiles, being able to scrub accurately is not a matter of privilege but sometimes a necessity. In iOS 7's Music app, you can do this by tweaking the scrub speed on your iPhone, iPod Touch or iPad.
Although the feature seems to be hidden, it's basically a tap-and-hold feature. Obviously, not everyone is going to need this feature so one might argue that the feature isn't really hidden but judge for yourselves.
How to Change the Scrubbing Speed in Music App on iPhone and iPad
Step #1. Open the Music app and play a song.
Step #2. When you are on the Currently Playing screen, you see the red vertical line along the time-bar. When you drag this, you scrub the song.
Step #3. When you drag it normally, the song scrubs at a default rate.
Step #4. Now, tap and hold and then slide upwards. You should see that the title of the song changes to “Half-Speed Scrubbing” or something else depending on how far you have slid your finger upwards.
Step #5. There are three scrubbing speed options available: Half-speed, Quarter-speed and Fine.
Step #6. “Fine” is where you scrub by the second.
So that's how you scrub. Tap and hold the red line, slide upwards to select a scrub speed and then drag across the screen (all this without letting go of the screen).
Like I said, the default scrub speed is okay in most circumstances. But if you are listening to podcasts or if you want precision-scrubbing, the “fine” level/gradation should come in handy as you can slide down the seconds, accurately.
Following a massive redesign to the Music app – which lost all of its former skeuomorphic glory to adopt a totally flat design – such features have been a good thing actually. Thankfully, features like being able to customize the menu haven't been changed.