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Hello, this is Six Minute English from BBC Learning English.
I'm Neil.
And I'm Georgina.
In this programme, we're talking about something that always surrounds us.
Noise.
Yes, whether it's the natural sounds of birdsong,
the windblowing or manmade 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 for the question about the measurement of sound,
which is in units called decibels.
According to a guide by the World Health Organisation,
what is considered the highest level we can be safely exposed to for a maximum of eight hours?
Is it A, 55 decibels?