There's no shortage of clever tricks to boost your iPhone's volume using just about anything from paper to ceramic bowls. Seedio is a new app that seeks to solve the same problem by turning several iPhones into one large speaker.
The app needs to be installed on every iOS device you want to turn into a speaker. Set up one of the devices as the hotspot by adding a list of songs, and then every other device receives music directly from the original. When it's all set up, every iOS device you have connected is synchronised and plays the same music at the same time -- effectively boosting the speaker volume 100 per cent for each device you add. You can add up to five devices at once.
Seedio worked surprisingly well in our tests. Running it on an iPhone and an iPad created a noticeable volume improvement. It could come in handy at a BBQ, for instance, where everyone has an iPhone but no one has outdoor speakers. You can also use Seedio to share what you're listening to with friends in the immediate area, or even as a remote if you have two devices in your house (one connected to the stereo receiving music, the other seeding music from your pocket).
Seedio is free for a limited time in the iTunes App Store.