[BC] Free Orban Loudness Meter for Windows now available

[Robert Orban]

As an offshoot from the Optimod 8585 development 
project, we have developed a stand-alone loudness 
meter for Windows, which we are releasing as a 
free public beta. The meter can be downloaded directly by clicking this link:

http://www.orban.com/meter/setup_Free_Orban_Loudness_Meter_1.00.exe

Be sure to read the readme file, which is the 
meter's manual. The installer will offer to open 
the readme as part of the installation process.

Here is the press release:

ORBAN INTRODUCES FREE LOUDNESS/LEVEL METERING SOFTWARE

San Leandro, CA, April 10, 2008 Orban today 
announced that the first public beta of Orban 
Loudness Meter software for Windows XP and Vista 
is now available for free download from www.orban.com/meter.

This is the first of a family of Orban meters. 
Future paid versions will offer upgraded features 
including logging, surround monitoring, and 
oversampled peak measurements that accurately 
indicate the peak level of the audio after D/A conversion.

This software simultaneously displays 
instantaneous peaks, VU, PPM, CBS Technology 
Center loudness, and ITU BS.1770 loudness. All 
meters include peak-hold functionality that makes 
the peak indications of the meters easy to see.

The software accepts two-channel stereo inputs. 
The VU and PPM meters are split to indicate the 
left and right channels. The PPM meter also 
displays the instantaneous peak values of the L and R digital samples.

The CBS meter is a"short-term" loudness meter 
intended to display the details of 
moment-to-moment loudness with dynamics similar 
to a VU meter. It uses the Jones & Torick 
algorithm developed at the CBS Technology Center 
and published in 1981 in the SMPTE 
Journal.  Created using Orban-developed modeling 
software, the DSP implementation typically 
matches the original analog meter within 0.5 dB 
on sinewaves, tone bursts and noise.

The Jones & Torick algorithm improves upon the 
original loudness measurement algorithm developed 
by CBS researchers in the late 1960s. Its 
foundation is psychoacoustic studies done at CBS 
Laboratories over a two year period by Torick and 
the late Benjamin Bauer. After surveying existing 
equal-loudness contour curves and finding them 
inapplicable to measuring the loudness of 
broadcasts, Torick and Bauer organized listening 
tests that resulted in a new set of 
equal-loudness curves based on octave-wide noise 
reproduced by calibrated loudspeakers in a 
semireverberant 16 x 14 x 8 room, which is 
representative of a room in which broadcasts are 
normally heard. In 1966, they published this work 
in the IEEE Transactions on Audio and 
Electroacoustics, along with results from other 
tests whose goal was to model the loudness 
integration time constants of human hearing.

In 2006, the ITU-R published Recommendation ITU-R 
BS.1770: "Algorithms to measure audio programme 
loudness and true-peak audio level." Developed by 
G.A. Soulodre, the BS.1770 loudness meter uses a 
frequency-weighted r.m.s. measurement intended to 
be integrated over several seconds ­- perhaps as 
long as an entire program segment. As such, it is 
considered a "long-term" loudness measurement 
because it does not take into account the 
loudness integration time constants of human hearing, as does the CBS meter.

Orban’s BS.1770 loudness meter uses the Leq(RLB2) 
algorithm as specified in the Recommendation. 
This applies frequency weighting before the 
r.m.s. integrator. The frequency weighting is a 
series connection of pre-filter and RLB weighting 
curves. The Orban meter precisely implements 
equations (1) and (2) in this document by using a 
rolling integrator whose integration time is 
user-adjustable from one to ten seconds.

Additionally, the Orban meter offers an 
experimental long-term loudness indication 
derived by post-processing the CBS algorithm’s 
output. This uses a relatively simple algorithm 
that attempts to mimic a skilled operator’s 
mental integration of the peak swings of a meter 
with "VU-like" dynamics. The operator will 
concentrate most on the highest indications but 
will tend to ignore a single high peak that is atypical of the others.

Researchers have long been curious about the 
Jones & Torick meter but been unable to evaluate 
it and compare it with other meters. Orban 
developed this software because the company 
believed it would be useful to practicing sound 
engineers and researchers and also because Orban 
is using it in its new Optimod 8585 Surround 
Audio Processor. Thanks to this free software, 
engineers and scientists will now have the 
opportunity to easily compare the CBS algorithm 
with others, including the BS.1770 Recommendation.

The Orban software runs on Windows XP and Vista 
computers having 1.5 GHz or faster Intel Pentium 
4 or Intel-compatible processors that implement 
the SSE2 instruction set. While the software can 
be driven by any installed Windows sound device, 
monitoring playback from an application like 
Windows Media Player requires the sound hardware to support Windows Wave I/O.

Bob Orban