audio loudness
Having to change the volume
because a commercial sounds much
louder than your favourite show is a
constant source of annoyance. Is there
an effective solution? Kevin Hilton
reports.
Pass the remote
A
ssessing broadcast the late 1990s. The starting point was following extensive testing of existing
transmissions can be to find a device that could quantify meters and working with a variety of
boiled down to ‘good comparative sound levels and make programme material.
pictures or bad pictures’ allowances for commercials being Having such a foundation for a set of
and ‘good sound or bad more heavily compressed than TV rules is a good start but, like anything,
sound’. So far so dramas, which tend to have a wider application is everything and BCAP's
objectively subjective. But audio is dynamic range. The established devices guidelines give broadcasters and post-
open to personal interpretation, which for measuring audio levels, PPMs (peak production houses some flexibility.
explains why broadcasters, meter programme meters) and the VU Peak-reading meters are still allowed
manufacturers, regulators and post- (volume unit) meter, are effective for if the maximum level of commercials is
production facilities have taken so long showing highs and lows but do not ‘at least 6dB less than the maximum
to establish methods of measuring have any great subtlety beyond that. level of the programmes’ to compen-
differences in loudness.
The
Algorithms were developed to show sate for any compression. Established
This is most likely also why there are
Advertising
the difference in sound levels caused practice for broadcasting analogue
not only discrepancies in
Standards
by compression, something that had audio is to peak the main programmes
recommendations between countries
Authority
previously been ‘measured’ solely in at no more than +8dBm, which means
but also in how individual national subjective terms through the human ads are restricted to +2dBm, or PPM
guidelines are implemented. In Italy the
(ASA) in the
ear. Meter manufacturers including 4.5 on a peak-reading meter.
Authority for Communications (AGCOM) UK eventually Chromatec, Dolby, Dorrough, TSL, RTW Advertisers spend vast amounts of
brought in rules during 2006 that
decided to
and DK-Technologies introduced money on making commercials and
govern commercials, promos, idents
take action
products for measuring loudness and want their ads to stand out, even
and the main programming, setting a
last year...its
while some broadcasters and facilities though they risk annoying the viewers,
maximum difference between all
Broadcast
adopted these, many others chose to causing them to turn down the sound
material of 0.6dB. A similar scheme was stick with PPMs or VUs. or, in extreme cases, mute it
introduced in the UK on 7 July 2008 but
Committee on The Advertising Standards Authority altogether. There is also concern that
this covers only discrepancies between
Advertising
(ASA) in the UK eventually decided to powerful clients will put pressure on
advertisements and programmes.
Practice
take action last year, perhaps facilities and dubbing mixers to use
Having to keep changing the volume
because a commercial sounds much
(BCAP) drew
prompted by the complaints about hard compression and so push the
louder than your favourite show has
up guidelines
noisy ads it received from over 100 limits of the rules.
people during 2007. In response, its Leading London audio post-
long annoyed the hell out of viewers.
on audio
Broadcast Committee on Advertising production companies, including Grand
In today's world of multiple digital levels of Practice (BCAP) drew up guidelines on Central and Jungle, have been working
channels, where there is no master
television
audio levels of television with broadcasters to test the loudness
control room housing operators who
advertise-
advertisements, which recommend the meters on the market and agree a way
can manually alter the levels to
produce a uniform output, the situation
ments, which
use of loudness meters. to implement the regulations that suits
has, if anything, got worse. Regulators
recommend
The BCAP recommendations, like everyone. But the problem of
those used in Italy, are based on two subjectivity prevails. "Loudness has
and other relevant official bodies
the use of documents produced by the always been subjective because there's
receive regular complaints, largely
loudness
International Telecommunication Union never been any way to compensate for
because two sound sources can
meters.
(ITU) in 2006-7. ITU-R BS1770 factors like the age of the listener but a
register the same on an audio meter (algorithms to measure audio compromise can be reached," said John
but one can still sound far louder. programme loudness and true-peak Bolton, technical director of IMD
Finding a solution to this seeming audio level) and ITU-R BS1771 (Independent Media Distribution),
paradox was a difficult proposition but (requirements for loudness and true- which developed a custom delivery
concerted efforts were made during peak indicating meters) were drafted system that performs a quality control
14 l ibe l January/February 2009 l www.ibeweb.com
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