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Swiss company Liechti reckons it has the answer for radio stations that want
to assess their audience approval. The firm has developed a recorder in a
wristwatch that lets broadcasters sample listening figures accurately. For four
seconds each minute, the watch records background noise, including the radio,
and converts the sounds into a digital signal. The watch’s software compresses
the signal and stores it in a memory chip. To find out who’s been listening to
which programmes and stations, all broadcasters have to do is compare the data
from the watches with compressed recordings of programmes for sequences that
match.