The Royal Albert Hall has unveiled a £2m speaker system designed to give the audience the same sound quality no matter where they are inside the auditorium.
It comprises 465 speakers and more than 15,000m (49,000ft) of cable.
It took 693 days to install, with most of the work carried out at night.
The last major improvement made to the hall's acoustics was in 1969, when giant discs were attached to the ceiling.
The fibreglass "mushrooms", as they became known, fixed an echo caused by the domed roof that had dogged the 148-year-old auditorium.
There are now speakers suspended from the ceiling all the way around the outside edge of the oval ceiling, as well as three speakers in each of the boxes that circle two tiers.
Detailed planning permission was required to make changes to the Grade I listed building in London.
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