rise above the jet noise

Technology Committee Meeting | 19-20 January 2005 | Glendale, CA 1

Rise Above the Jet Noise

AVX Adaptive Encoding

Jeremy Hoenack,CAS, MPSE

Sound Trax Studios

[email protected]


AVX Inflight Sound Overview 1

• Subtle dialog is clear and easy to understand

• Underscore and background effects that are normally lost are crisp and clear

• Film sound-track masks jet noise instead of reverse

• No high sound levels, no ear pain, no need to constantly adjust volume, natural sounding

• More immersion in film – more positive flight experience

• No new equipment – compatible with all IFE systems



• Psycho-acoustic adaptive encoding • Parses, disassembles, restructures the dynamic range in

real time – constantly adapts to program content

• Enables full optimization of dynamic range to needs of human hearing without severe limitations of existing technology



• Adaptive Encoder vs. Compressor/Limiter

• DSP intensive vs. analog design

• Unlimited design possibilities vs. practical limitations• AVX “reverse-compression” emulates how brain deals

with high ambient noise like conversation on a jet


IFE sound system – The Titanic

• Destined to cruise over sea of noise – 75db SPL (From take-off to landing, like sitting next to a vacuum cleaner, a hair dryer, or standing in the shower.)

• Can not change course very quickly – prohibitive costs• Needs to accommodate all kinds of people and stuff –

variety of headphones, hardware, media


Film sound track – The Iceberg

• Only the peaks are noticed

• Most of it obscured by sea of noise• “Big picture” missing – no context• Tells how to perceive visual (picture)• Controls emotional response eg. fear• Conveying the emotional content is

life or death matter to a film• Low emotion = low immersion

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How much is hidden?• Top of iceberg is 90db• 15db is revealed

• Sea of noise level 75db

• 35db obscured by sea of noise

• Over 2/3 of sound (dynamic range) is buried beneath sea of noise

• Bottom of iceberg is >40db

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Human hearing 1

• Normal range 35-72db for speech (intelligibility)

• Below 75db sea of noise in cabin

• = 0% intelligibility• Good news - No need to have

foreign language tracks

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Human hearing 2

• Lose intelligibility if average speech less than 15 db above noise – 75 + 15 = 90db

• Narrow range for speech 15 db – average at 90db (unsafe), peaks at 97db

• Bad news - Above 85db – no increase in intelligibility – instead oppression and discomfort

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How to uncover the iceberg?

• Can not change noise level - 75db

• Iceberg is 50db high (dynamic range) 90db-40db

• Can not lift above noise level 5db+75db=125db !!!!!

• 90db beginning of “unsafe levels” (D.O.L.), discomfort

• 2 hours @ 100db = hearing damage – long flights?

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painpainear damageear damage ear damage“unsafe”“unsafe”discomfort


Existing technology ineffective 1

• Squeezes to 30-40db range– Ear discomfort from peaks– Obscured mood fx / underscore– Straining to understand – low

intelligibility

• Jet noise “in front” of sound track

– Like looking through dirty glass

• Constant volume adjustments

• Little or no immersion in film

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Existing technology ineffective 2

• Operates from top down – Characteristics of electronics– Compressor– Limiter

• Unnatural

– Real life is opposite

• Limited by artifact -claustrophobic

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Human hearing psychology 1

• Decoding, decoding, decoding – Sound into phonemes– Phonemes into words– Words into language– Language into meaning

• Brain overwhelmed– Sound buried in noise– Playing “catch-up” -Trying to figure out

what was missed while trying to continue in-the-moment decoding

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Human hearing psychology 2

• Failure & frustration– No one likes to feel stupid

– Not knowing “what’s going on”

– Missing vital information that “others know”

• Ability to make emotional associations is blocked by obsession to decode

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Brainy brain has no problem

• Why we can have a normal conversation above the noise?

• Brain uses “reverse-compression” to raise bottom with little affect on top

• High intelligibility with acceptable levels

• Normal speech pattern -subconsciously adapt to ambient noise

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AVX one-ups the brain 1

• Extreme reverse-compress/limitmicro-encodes detail

• Top is normal – ‘must be normal’

• Comfortable levels

• Dynamic range fits

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• Raises bottom of sound track above noise

• Mask effect – sound track is relentlessly dominant

• Mind tunes out and soon forgets subordinate jet noise (it wants to)

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• Enhanced aural cues ~100% intelligibility including spatial cues

• Sound decoding easy & relaxing

• Brain resources free to make deep emotional associations

• High level of immersion in film

• Tune out flying – trip is shorter and more enjoyable

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• Clips mixed with jet noise @~73db for simulation

• All clips are at the same volume level

• Louder sounds are similar• AVX raises quiet sounds

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Film Clips from SECONDHAND LIONS comparing

WAEA 1289-1 spec. audio with AVX encoded audio


Per 1289-1 spec. #1

Inaudible under bridge, cop, plane approach

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AVX Encoded #1

Distinct snoring & ambience under bridge, plane

approach


Per 1289-1 spec. #2

Inaudible off camera speech, music and ambience

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AVX Encoded #2

Speech is intelligible, distinct music and

ambience


Per 1289-1 spec. #3

Inaudible lion growls, weak ambience, lack of presence

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AVX Encoded #3

Distinct lion growls, ambience is dominant,

speech has good presence


Per 1289-1 spec. #4

Inaudible bell-tree, no presence to music and ambience

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AVX Encoded #4

Distinct bell-tree, good presence of music and

ambience


Per 1289-1 spec. #5

Inaudible ambience, unclear speech at end

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AVX Encoded #5

Better ambience, distinct speech at end “learn to do

without” & “uh-huh”


Per 1289-1 spec. #6

Speech is frustrating - unclear, music missing until end

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AVX Encoded #6

Speech is intelligible, music is marginally audible


Per 1289-1 spec. #7

Speech is marginal, jet noise dominates

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AVX Encoded #7

Speech is crisp and present, music and ambience

dominate over jet noise


Per 1289-1 spec. #8

Jet noise dominates, missing/obscure lion sound,

ambience very weak

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AVX Encoded #8

Sound track dominates,lion & ambience clear,

presence, “in the movie”


Per 1289-1 spec. #9

Jet noise dominates, speech lacks presence,

ambience very weak

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AVX Encoded #9

Track dominates, speech is intimate & clear, ambience, reverb, presence, “in the movie”


Summary

• AVX solves the difficult noise problem for IFE films

• Film perceived as intended

• High immersion > enjoyment > successful distraction

• Greater satisfaction & positive impression of flight

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AVX turns the iceberg into a

breeze, giving IFE

a free ride


AVX 757 Simulator Demo

• 5-8 after show, 10 minute drive west near Disney & Warner Bros.

• Sound Trax Studios2815 West Burbank Blvd.Burbank 818-842-6300

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AVX would like to thank

• WAEA attendees

• John Salzman

• John Eargle & Chris Foreman –sound reinforcement research

• Avid Airline Products – headphones

• Sound Trax Studios

• New Line Cinema

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rise above the jet noise

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