快猫短视频

TELEPHONE networks of the future will work by sending speech in the same form
as Internet data鈥攊n discrete packets. But anyone who has tried making a
phone call over the Internet will know what happens when the network gets
congested: speech can end up sounding like a strangled underwater garble.

Now PsyTechnics, a 拢2 million spin-off from British Telecom鈥檚 research
laboratory, believes it has the answer. It has developed a 鈥渃omputer model of
human irritation鈥� that senses when Internet voice lines are becoming annoyingly
congested and acts to supply more network capacity鈥攚ithout your hearing so
much as a wobbly vowel.

Future networks, both land-based and mobile, will digitally compress speech
into Internet protocol (IP) data packets. When the Internet is busy, some
packets are lost or corrupted. The network automatically sends them again until
they get through. This is fine for ordinary data, but it distorts speech because
packets arrive out of sequence.

鈥淎ll the usual test methods, like sending test tones down the line, are
useless with IP networks,鈥� says Mike Hollier, chief executive of PsyTechnics.
鈥淭he only sure way to know when there is an overload is when people complain,
which is the worst possible way to run a network. So the operator has to play
safe and send less data. Efficiency gain is then lost.鈥�

Hollier and his colleagues played distorted Internet speech to hundreds of
volunteers and asked them to say when they had problems understanding what was
said. They then used the results to build a computer model which has the same
鈥渋rritation鈥� threshold as a human would when sound quality deteriorates. This
controls a 鈥渄ata gate鈥� that balances data flow against demand to ensure that the
speech never degrades enough to upset callers.