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Hello, this is 6 Minute English from BBC Learning English.

I'm Neil.

And I'm Georgina.

In this program, we're talking about something that always surrounds us.

Noise.

Yes, whether it's the natural sounds of birdsong,

the wind blowing or man-made noise, like traffic or music.

There's always something we can hear.

Of course, there are sounds that we like to hear,

and then there are those sounds that really great,

annoy or irritate.

Like the beeping sound on a reversing lorry

or someone drilling a hole in the road.

Indeed, soon we'll be looking at the language of noise

and hearing about ideas for making the world a quieter place.

But let's kick off with a question about the measurement of sound,

which is in units called decibels.

According to a guide by the World Health Organization,

what is considered the highest level we can be safely exposed to

for a maximum of eight hours?

...