The speaker on the iPhone 5s is fairly powerful given the handset's small size, but there's an easy way to get more audio oomph. I use this trick whenever I'm listening to music while doing the dishes or taking a shower. Just point the iPhone so that the bottom-mounted speaker is facing the wall, so that the audio reverberates. You'll notice a fairly dramatic volume boost. Sure, a Bluetooth speaker will give you more volume, but this "hack" works in a pinch.
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