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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

Control of Loudness -LEQ Programme

Julian Pinn,

Senior Sound Consultant,

Dolby Laboratories Inc.


Overview
Overview

  • Typical Natural Sound Levels

  • Fundamental Issue

  • Solution: Dolby Model 737

  • Current news

  • Discussion


Typical natural sound levels

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


Fundamental issue
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.


Solution
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.


Dolby model 737 soundtrack loudness meter leq m

Dolby Model 737Soundtrack Loudness Meter - Leq(m)

Time averaging

Frequency weighted curve

Cheap and easy to install

5.1 compatible


Dolby model 737 soundtrack loudness meter leq m1
Dolby Model 737Soundtrack Loudness Meter - Leq(m)

dBSPL

  • Time averaging

110

105

100

95

90

85

80

75

Time


Dolby model 737 soundtrack loudness meter leq m2

Modified CCIR curve (offset of 5.6 dB - ref. 2 kHz)

dB

Frequency

Dolby Model 737Soundtrack Loudness Meter - Leq(m)

  • Frequency weighting


Current news
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.


Control of loudness leq programme1

Control of Loudness -LEQ Programme

Julian Pinn,

Senior Sound Consultant,

Dolby Laboratories Inc.


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