Advertisers like to make their TV ads seem louder than the programmes they accompany, so they stand out. Broadcasters can already limit the peak sound level in commercials to match that of the programmes, but this does not really solve the problem because it is not the peak loudness that people find annoying, but the average loudness level over a period of time.

Busy, complicated soundtracks with lots of simultaneous dialogue, sound effects and music – typical of many US dramas, such as ER – seem louder than something with more intermittent sound, even if both peak at the same level.

Programme makers will often arrange for dialogue to peak much lower – by around 8 decibels – than the upper sound limit set by broadcasters, in order to make loud sound effects such as explosions seem more dramatic. While these loud sounds do hit the limit, viewers find this practice perfectly acceptable.

In ads, by contrast, the quiet passages are made nearly as loud as the noisiest ones, and this is what makes viewers want to turn the volume down. The trouble is, there is no standard, universally agreed way for production companies and broadcasters to measure these average loudness levels.

Dynamic range

Broadcasters try to take the compressed “dynamic range” of advertisements into account when setting transmission sound levels. Chris Hearn of the British independent broadcaster Granada TV in Manchester says that the limits for the peak sound level for material in which the sound is compressed in this way is normally set at a lower level than for a drama with a full dynamic range.

Today’s electro-mechanical sound meters that display average loudness are not sophisticated enough to take into account the way the human ear perceives the sustained sound. But this is set to change.

Prompted by complaints from viewers, the International Telecommunication Union (ITU), which sets standards for the broadcasting industry, is developing a metering system that marries people’s subjective perception of loudness with electro-mechanical measurement.

Hundreds of clips

Engineers at the ITU’s Communications Research Centre in Canada have been playing volunteers hundreds of clips from programmes and ads contributed by broadcasters from around the world.

Later in June they will take the data on how people perceived average loudness in certain types of material and use it to build a range of software-driven meters that broadcasting technicians will put to the test.

A report on the technology needed to quell ad noise is expected to be circulated among ITU members in August.

Steve Lyman of the ITU says he is confident that this will give the TV industry a better way to control loud ads. Even in stations using automatic computerised transmission, the new metering software could be installed in a video server, where it will analyse the programmes and ads and adjust the sound in real time as they are broadcast.

British Airways is testing these natural sounds—merged with specially
composed music—in executive lounges at Heathrow, Gatwick and Manchester
airports, to see if they relax tired and stressed travellers as they wait for
their flights.

The sounds have been processed and mixed in an attempt to evoke the ambience
of a meadow on a sunny day. Fifty sets of strategically placed stereo speakers
are used to generate a “sound image”.

BA says travellers have complained that its lounges are merely “stuffy,
functional waiting rooms” which offer them no personal space. A BA spokesman
says the company aims to “bring the outside inside”.

The airline hired the Japanese company TOA to build the sound system, which
creates an ambience so subtle as to be almost subliminal. “You may not take any
notice of the sounds—you hear it but you don’t hear it,” says Brett
Downing, director of TOA’s British arm. “But there are things like duck calls at
specific times of day.”

Ironically, for a system designed to calm, the material was assembled by
Brian Robertson, formerly guitarist with the 1970s heavy metal band Thin Lizzy.
Robertson and his partner at Yodel Studios in Brentwood, Essex, Rob Jeffries,
were brought in after BBC sound effects recordings of bird song were deemed “too
boring”. The pair recorded the dawn chorus, streams and the ambient sound of
meadows on digital audio tape for transfer to CD. The TOA system employs a
computer-controlled CD jukebox that schedules the sounds and music.

As long ago as 1975 psychologists showed that quiet music, with a slow rhythm
and no sudden harmonic changes, can reduce the aggression of a person who has
been insulted. But Peter Simpson, a psychologist at the University of Surrey in
Guildford, wonders whether adding natural sounds can help further: “The idea
must be based on the notion that the sounds of nature are by definition calming.
Listening to bird song might be effective because it will attract the
attention—spot the woodpecker, that kind of thing. But why would the
waterfall be calming without the physical coolness, breeze and maybe negative
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