iPhone - Audio- How can I increase the volume (make sound louder) on my iPhone speaker?

The iPhone speaker is good for a portable device, but it's not great. If you don't have a dock or external amplified speakers you can hook up to the headphone out jack you're stuck with the stock speaker. Here are a few tips to make the audio louder:
1. Maximize the volume within the app you're using by pressing the side volume buttons while you're already running the app.
2. Place the iPhone flat on a table and the volume will get a boost.
3. If you're holding the iPhone in your hand (for example on speakerphone) cup the inside of your palm around the back of the phone behind the speaker. This will focus the sound in your direction and it should be louder.
4. To maximize sound with the stock iPhone speaker, when the iPhone is lying down put it in front of a wall, window, or other surface. Place the iPhone on its back a couple of inches from the wall, and angle the iPhone at a 45 degree angle to the wall with the speaker facing the wall. Sound will bounce off the surface and the tabletop, increasing the volume and depth of the music.