3-78
OPERATION ORBAN MODEL 8685
Appendix A: Using the ITU BS.1770 and CBS
Loudness Meters to Measure Loudness Control-
ler Performance
In 2009, the ATSC released a Recommended Practice: Techniques for Establishing and
Maintaining Audio Loudness for Digital Television (A/85:2009). This specifies use of a
long-term loudness meter based on the ITU BS.1770 algorithm for assessing and set-
ting the loudness of DTV broadcasts.
For many years, Orban has used the Jones & Torick loudness controller and loudness
measuring technology
1
in its products for loudness control of sound for picture. De-
veloped after 15 years of psychoacoustic research at CBS Laboratories, the CBS loud-
ness controller accurately estimates the amount of perceived loudness in a given
piece of program material. If the loudness exceeds a preset threshold, the controller
automatically reduces it to that threshold. The CBS algorithm has proven its effec-
tiveness by processing millions of hours of on-air programming and greatly reducing
viewer complaints caused by loud commercials.
Since first licensing and using the CBS algorithm in its Optimod-TV 8182 back in the
early ‘80s, Orban has continually refined and developed this technology. In the last
quarter century, audio processors from Orban and CRL using the CBS loudness con-
troller have processed millions of hours of on-air television programming — an un-
surpassed track record that no other subjective loudness controller technology can
claim.
Because the ATSC recommends the BS.1770 algorithm, many engineers facing the
problem of controlling broadcast loudness have wondered how the CBS and BS.1770
technologies compare. The purpose of this paper is to present, using both meters,
comparative measurements of the output of Orban’s current audio processors
2
that
use our latest refinement of the CBS loudness controller technology.
3
Test Setup
A stereo recording of approximately 30 minutes of unprocessed audio from the out-
put of the master control of a San Francisco network station was applied to the 2.0
1
Jones, Bronwyn L.; Torick, Emil L., “A New Loudness Indicator for Use in Broadcast-
ing,” J. SMPTE September 1981, pp. 772-777.
2
Optimod-Surround 8585 and 8685, Optimod 6300 (with version 2.0 and higher
software), and Optimod-PC 1101 and 1101E (with version 2.0 and higher software).
3
For a discussion of the CBS and BS.1770 technologies, see
http://orban.com/meter/Technology.html
. The ATSC A/85:2009 document also dis-
cusses the BS.1770 algorithm.
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