There are lots of sites that give various methods for speaker amplification:
I have tried these but none of them were great.
Is there a better way to amplify my iPhone's speakers?
We can even rotate the cup to amplify in a particular direction.
The easiest way I know, when you're at home or outside and don't have any gadgets or items, is simply placing your phone next to a wall or ideally in a corner with the speakers facing the wall. The sound waves will reflect off the wall and more of them will get directly into your ear.
To understand this, imagine a speaker in the middle of a room with you standing on the right side of the room. The sound waves move in all directions and only one part of them will directly get into your ear. The rest will first reflect off the left, top and bottom walls before they get into your ear. They will lose some of their loudness and will get there with some delay: You here a slight echo (of course depending on the size of the room). So if the speaker is in the corner, more of the sound waves get directly into your ear or only with a minimal delay.
It isn't that much louder, than placing it in a bowl or toilet paper roll but you will still hear a difference.
You can amplify your mobile speakers by using induction speakers which boosts the volume of any device with an external speaker without any wires.
How does it work? It's grabbing the magnetic field of the speaker using induction, and then running that signal into its own amp and speakers.
If your purpose is different and you want to make as much noise as you can (e.g. you're a heavy sleeper), then put your phone into a glass/mug.
Similar to @kenorb's answer, but instead you could place your phone in a metal saucepan. I have done this while on holiday and I had forgotten to bring speakers and it works really well. Also tilting the pan on it's side and facing it to where you are sitting or 'boogieing' will make it more directional and louder.
I've had success by placing the phone with the speakers facing up in a large, tall ceramic/glass/metal bowl. Plastic or wood doesn't work as well.
It's not too much louder, but it does make a difference.
I have gone to android now, but when I had an iPhone, I had several "horn amplifiers" laying around. I think I paid $3 each. These are very cool and work fantastically. It's a piece of silicone the phone just sits in it (see below).
Yes if you have one in your home or office it will help you to make amplifier;all you have to do is make a rectangular hole that your phone fits. You can increase effect by adding conical things like paper-cup or even closing one side will do more for you. Also one more thing more longer the tube is more the voice....
Also Paper Clips may help you to keep it on desk.
