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Control of Loudness - LEQ Programme

In this presentation by Julian Pinn, Senior Sound Consultant at Dolby Laboratories, we explore the critical issue of loudness control in audio production. We examine typical natural sound levels and the fundamental challenges posed by inconsistent recording levels that impact sound quality. The discussion highlights the effectiveness of the Dolby Model 737 Soundtrack Loudness Meter (Leq(m)) in assessing perceived loudness and maintaining dynamic range. Recent industry standards, including guidelines from the Trailer Audio Standards Association and the British Standard BS5550.7.4.2, help ensure audio consistency across cinema and commercial releases.

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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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