SMPTE Dedicates New Technology Committee to Cinema Sound

The Society of Motion Picture and Television Engineers, SMPTE, has created a new technology committee, TC-25CSS, dedicated to cinema sound. The committee will work to update SMPTE standards and recommended practices to address opportunities created by technical advances that have emerged since standards last were created, as well as to improve the quality and consistency of cinema sound.

"Improvements in measurement technology, digital sound delivery, and in sound reproduction equipment, as well as the greater detail and dynamic range of movie soundtracks, present challenges when providing cinema sound," said Brian Vessa, executive director of digital audio mastering at Sony Pictures Entertainment and chair of the new SMPTE committee.

TC-25CSS is the first SMPTE technology committee dedicated to cinema sound. Similar to the introduction of Digital Cinema to improve the consistency of image display, the members will investigate and standardize new sound measurement techniques aiming for consistency in sound reproduction between the mixing stage and different cinema environments. Existing SMPTE standards and recommended practices help minimize variations, but cinema sound quality still depends on the skill and hearing acuity of the technician making adjustments.

TC-25CSS was formed following a study by the Theater B-Chain Study Group, which tested current test equipment and methods, measured reference and commercial theatres, and collaborated on observations and results. The committee currently has 130 members, representing about 90 companies and academic institutions from 14 countries.

The theatre sound chain is the sound track on the film stock, projector sound reader and Dolby decoder.   B chain refers to power amplifiers, crossovers and speakers, including cinema room equaliser response, EQ

As TC-25CSS works to standardize techniques and tools for optimizing sound systems and theatre acoustics, the committee will correlate human sound perception with the science of sound reproduction and measurements as the underlying principle. Current activities include development of a recommended practice for measurement and calibration of B-chain sound systems using modern standards and measurement, creation of a standard pink noise test signal, a final report on data and findings from the Theater B-Chain Study Group, and work by two new study groups examining immersive audio systems and new electroacoustic measurement methods and target curves.

"This is the first time since the late '70s that cinema sound has been addressed in depth," said Mark F. Collins, director of projection technology for Marcus Theatres. "Over the past three decades, significant changes in audio systems have taken place. Our hope is that, through the work of the new SMPTE committee and subcommittees, the tools used to measure audio signals will be brought up to date. With signal-testing tools that support very consistent audio quality throughout the industry, cinema owners can and assure movie creators that what's being reproduced in the field is consistent with the studio mix."

In the upcoming SMPTE Standards Webcast ‘Cinema Sound Systems — Raising the Bar Through New Standards’, scheduled for 12 March, Brian Vessa will discuss topics including current SMPTE standards, the new committee's work, and the impact of new and emerging immersive cinema sound systems on the standards-creation process. The webcast is free and open to all.  www.smpte.org