Beak quiet! Are these the loudest birds in the world?

Some birds sing. Others chirp. But a few can make a noise louder than a plane taking off!

Scientists say they've discovered two birds, which they believe could be among the noisiest in the world.

Experts measured calls from more than 100 different species, and found that those from the bare-throated bellbird and red-legged seriema were the strongest.

The team added that their research could help explain how some birds are able to produce such powerful sounds.

Researchers from the University of Massachusetts Amherst in the America decided to take a closer look at a range of birds from the United States and Brazil.

They measured the calls of 123 different species, most of which had never had the volume of their calls measured before.

Experts found a big difference between the quietest and most powerful ones.

For example, a hummingbird's call measured around 64 decibels, which is around the volume of a normal conversation.

At the other end, the bare-throated bellbird and red-legged seriema were the loudest - both reaching more than 120 decibels.

The team also wanted to find out what helps these birds make such powerful sounds.

They discovered that birds with bigger bodies and stronger muscles tended to produce louder noises.

They think that may help them push more air when they call.

The birds also tended to have wider beaks, which could also help increase the volume.

Scientists say they still don't know exactly why these birds need to make such noisy calls.

They hope that studying more species will help them solve the mystery.