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Loudness Issues in Cinema 5 per cent

EU Report – 25 June 2014

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Scary Quote One

(extracted from page 299 of 345 Ajuntament de Barcelona BOPB de 02-05-2011)

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The owner or person responsible for the activity shall be responsible for the smooth operation of the limiter-recording equipment, so you will need to maintain a permanent maintenance service that allows you, in case of failure of the equipment, repair or replacement within no more than one week from the onset of the fault. It will also be responsible for having a copy of the logbook limiter, which will be available to the municipal officers upon request, which will have to be substantiated any abnormality suffered by the team, as well as repair or replacement by the official maintenance service, indicating the date and technical personnel responsible.

Context and Elaboration

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ORDENANZA DEL MEDIO AMBIENTE BOPB de 02-05-2011

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ANEXO II.15 Clasificación de las actividades en función del nivel de emisión acústica interior

Grupo I queentre 95 - 105 dB queA)) Discotecas

Cines

Salas de baile

Auditorios

Salas de fiesta con espectáculo

Talleres de reparación de vehículos con chapa Cerrajerías

Cafés teatro y cafés concierto

Karaokes

Locales para ensayos musicales o similares

Estudios de grabación de sonido

Teatros

Talleres de aluminio

Planchisterías

Establecimientos donde se realicen actuaciones en vivo

Centros docentes de música, teatro, danza y similares

Context and Elaboration

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ORDENANZA DEL MEDIO AMBIENTE BOPB de 02-05-2011

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ANEXO II.15 Clasificación de las actividades en función del nivel de emisión acústica interior

Grupo I queentre 95 - 105 dB queA))

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Cinemas – the common noun for a movie theater or complex in the EU – were not included in the first versions of the ordinance.

In 2002 the Leq solution for commercials and trailers mostly solved the problem for 35mm. Then came the new “Wild West” of the higher bandwidth DCP.

This Barcelona solution is typical in how this is coming up – fragmented local solutions.

Rumors of long passed Italian communities attempting to pass laws, but they did not complete.

The CST in France is beginning work on this subject and has promised to communicate results as they develop.

There is a common and unstudied thread that links “loudness” complaints to distortion.

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Present and Future

ORDENANZA DEL MEDIO AMBIENTE Reflections

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ANEXO II.15 Clasificación de las actividades en función del nivel de emisión acústica interior

Grupo I queentre 95 - 105 dB queA))

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The solution has been a question: How does one get an 8 channel limiter for a cinema? Where does one measure in the room? For how long is the measurement taken?

Barcelona is in North-East Spain. In North-West Spain, the City Hall of the regional capital Santiago de Compostela, Galicia, sent a letter to a cinema currently in design 2 weeks ago stating that in compliance with European Union directives of 2011, the level in the cinema may not surpass 90 dBA – but they don’t specify the EU directive, only the Barcelona Ordinance. Note that they devolved the allowed level from105dB, and make no mention of where or for how long to make the measurements and whether there can be peak levels, etc.

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The Flemish Law

Another Carry Forward from Limiting Concerts, etc. Specifics (1) Akoestisch Onderzoek in Bioscoopzalen – 
 A detailed study derived from 5 cinemas

Ministerial Order determining the requirements that a sound system in digital cinemas must satisfy

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Different levels for children and adult movies (85 and 95)

LAslow measured for whole movie and the maximum value must not be over the specified amount.

A limiter is suggested but not obligatory

There is a requirement for 1 year (re)calibration (with procedures) and with a report to authorities; 
 and a log that ‘tracks the evolution of the main fader’ and a 3 month SPL reading of the auditorium.

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The Flemish Law

Another Carry Forward from Limiting Concerts, etc. Specifics (2) Akoestisch Onderzoek in Bioscoopzalen – A detailed study derived from 5 cinemas

Ministerial Order determining requirements that a sound system in digital cinemas must satisfy

Only applicable in the north of Belgium – the Flemish Region

Not unthinkable that this would/could be a template for other territories of the EU, 
 though no one I spoke to has heard any ripples of this.

In fact, several clever installers and consultants in neighboring countries hadn’t even heard of it~!

There appears to have been an earlier attempt of a handshake “self-regulating” period.

Some sample SPL levels taken of various theaters including the Flemish tests

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The Flemish Law

Report from a Cinema Chain Specifics (3)

1. We where consulted by the government when they worked out this regulation.

2. We pushed to keep it as much as possible within the existing calibration methods 
 not to add to much work.

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3. The levels we where used to play at are also still the same after the regulation was passed. 4. One element that was crucial to me is that the fader level limitation is linked to the source loudness in dBFS, meaning if the mixing changes, we can adapt accordingly the fader level.

5. Difficulty today is to have a dBFS reading of an entire movie – 
 this should be part of the movie metadata.

6. I.e., and e.g.; For a regular movie where the fader in a large room can be at maximum -8db
 if the movie has a -21dBFS measurement M weighting over the whole movie –
 if this measurement is lower we could turn up the fader.

Reminder

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‘7’ – and ‘7’ Is The Dolby Dial

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From 4 to 10 it's 5/3dB per 0.5 step.

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From 0 to 4 – 10dB per 0.5 step.

10 = 95dB

6.5 =83.33

3.5 = 65dB

9.5 = 93.33dB

6 = 81.66dB

3 = 55dB

9 = 91.66dB

5.5 = 80dB

2 = 35dB

8.5 = 90dB

5 = 78.33dB

1 = 15dB

8 = 88.33dB

4.5 = 76.66dB

7.5 = 86.66dB

4 = 75dB

7 = 85dB

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Reminder

‘7’ – and ‘7’ Is Available Dynamic Range Theory

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Each quantization bit adds 6 dB in possible dynamic range 144 dB (24 x 6) = for 24 bit systems (D-Cinema)

126 dB for 21-bit systems

120 dB for 20-bit systems

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108 dB for 18-bit systems

96 dB for 16-bit systems (CD’s)

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Tangent: Power Requirements to achieve increased loudness – 3 dB doubles the acoustic power required

By 10 dB raises the acoustic power required ten times

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Reminder

‘7’ – and ‘7’ Is Distance from the Speaker

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Inverse Square Law Applies; Assume we are equipping an 80 ft x 52 ft 
 (24m x 16m) theatre

For screen and subwoofer channels, 
 2/3 the length of the length is 52 ft or 16m

Inverse square loss = 20 Log (16) = 24 dB

For surround channels, ½ the width of the theatre is 26 ft or 8m

Inverse square loss = 20 Log (8) = 18 dB

From Barry Ferrell – QSC Audio Products, Inc.

report: Sound Systems for Alternative Content

Safety mechanisms of the Ear

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(extracted from Physics of Music Lecture Notes

Instructor: Guy D. Moore August 3, 2006; McGill University)

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There is a set of muscles attached to the eardrum, and another set attached to the malleus. When these muscles contract, they tighten the eardrum, reducing the efficiency of sound transmission, and draw the malleus back from the eardrum, reducing the efficiency of transmission between the eardrum and the malleus. That is, these muscles can partially “turn off” the propagation of sound from the outside into your ear.

When there is a loud sound, a reflex called the acoustic reflex activates these muscles. This reduces the danger that a loud sound will cause damage to your ear. For future reference, the reflex usually occurs for sounds louder than about 85 deciBels (dB).

Safety mechanisms of the Ear

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(extracted from Physics of Music Lecture Notes

Instructor: Guy D. Moore August 3, 2006; McGill University

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However, like all reflexes, there is a delay before the reflex starts. In this case, it is about 30–40 milliseconds, or 0.03 to 0.04 seconds. This delay means that sudden loud sounds go through before the reflex can act. This means that sudden loud sounds (gunshot) are much more likely to damage hearing than steady loud sounds (jackhammer).

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Also, sudden loud sounds are more likely to be in the upper register of hearing, which is part of the reason that deafness usually progresses from high to low pitch.

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…to be continued EU Report – 25 June 2014 – C J Flynn, Digital Test Tools, LLC

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Documentation at: 
 www.dcinemacompliance.com/loudness/eu_loudness.zip

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With thanks to:

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Philip Newell

Frank De Neeve at CineServer

Jaume Puig at Dolby Spain

Mark Waldman at Karo Cinema

Mirko Heukemes at dcinex

Nicolas Hamon at Kinopolis Group