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Control of Loudness - LEQ Programme

Control of Loudness - LEQ Programme. Julian Pinn, Senior Sound Consultant, Dolby Laboratories Inc. Overview. Typical Natural Sound Levels Fundamental Issue Solution: Dolby Model 737 Current news Discussion. Aircraft carrier - Jet takeoff with afterburner @ 15m. Conversation.

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Control of Loudness - LEQ Programme

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  1. Control of Loudness -LEQ Programme Julian Pinn, Senior Sound Consultant, Dolby Laboratories Inc.

  2. Overview • Typical Natural Sound Levels • Fundamental Issue • Solution: Dolby Model 737 • Current news • Discussion

  3. Aircraft carrier - Jet takeoff with afterburner @ 15m Conversation Jet flyover @ 350m Diesel train, 45mph @ 35m Threshold of hearing Rock gig Bird song Pain Very quiet Quiet Moderate Very loud Typical Natural Sound Levels

  4. Fundamental Issue • Peak recording levels (headroom) was being used for average record levels of many competitive spots. • Loss of standard replay level. • Loss of dynamic range, thus quality. • Independent peak-limitation did nothing for quality, and caused difficulty for international releases.

  5. Solution • Research the most suitable way of measuring the perceived loudness and annoyance of a section of film sound. • Produce a tool to be able to measure this new limitation. • Establish a world-wide standard.

  6. Dolby Model 737Soundtrack Loudness Meter - Leq(m) Time averaging Frequency weighted curve Cheap and easy to install 5.1 compatible

  7. Dolby Model 737Soundtrack Loudness Meter - Leq(m) dBSPL • Time averaging 110 105 100 95 90 85 80 75 Time

  8. Modified CCIR curve (offset of 5.6 dB - ref. 2 kHz) dB Frequency Dolby Model 737Soundtrack Loudness Meter - Leq(m) • Frequency weighting

  9. Current news • Trailer Audio Standards Association requires a limit of all US trailers to 85 dBLeq(m). • Screen Advertising World Association recommends a limitation of all commercials to 82 dBLeq(m). • The British Standard (BS5550 7.4.2) specifies the Leq(m) system and the currently practiced industry levels. • An International Standards Organization (ISO) new work item specifies Leq(m) for perceived loudness assessment. • Motion Picture Loudness Committee obtained agreement between Dolby, dts, and SDDS that all UK trailers and commercials be rejected that exceed BS5550 7.4.2. • Many screen advertisers standardized on 82 dBLeq(m) and Dolby Digital as the commercial release format. • Dolby Laboratories Inc. (RoW) require all cinema commercials and film trailers to be mastered in accordance with BS5550 7.4.2 from 1 January 2002.

  10. Control of Loudness -LEQ Programme Julian Pinn, Senior Sound Consultant, Dolby Laboratories Inc.

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