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ACOUSTIC ENHANCEMENTTutorial
AES 59th Conference – July 2015Acoustic Enhancement | 2
purpose
• adaptation of the acoustic environment tothe requirements of the performance
ØA room suited for this
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purpose
• adaptation of the acoustic environment tothe requirements of the performance
ØSound good for an event like this
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purpose
• adaptation of the acoustic environment tothe requirements of the performance
ØA room that looks like this
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purpose
• adaptation of the acoustic environment tothe requirements of the performance
ØTo sound like a room likethis
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what?
• reverberation• early reflections• direction
(lateral/medial/elevation)
• loudness
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reverberation
natural acoustics:• room volume• absorption• coupled rooms
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reverberation
electronic enhancement:• regeneration• synthetic generation (in-line)§ all pass filtering§ multiple reflections/FIR filtering§ sampled reverb/convolution
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early reflections
natural acoustics:• orientation of reflectors• placement of absorption
electronic enhancement:• electronic delay• redistribution
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direction
natural acoustics• room shape• distribution of absorption/reflection
electronic enhancement• balance of loudspeakers in enhancement
system
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loudness
• passive/natural acoustics§ inverse proportional to volume and absorption
• regeneration§ proportional to RT60
• in-line§ relatively independent of acoustic parameters
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electronic systemsacoustic feedback
ways to control:• microphone configuration• loudspeaker configuration• loudspeaker/microphone relation
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electronic systemsstability improvement
• multiple (independent) channels§ band limited - high gain/channel§ wide band – low gain/channel
• linear EQ
• de-correlation§ time variant§ time invariant
• echo cancelling
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implementations
LARES
Assisted ResonanceRODS
ERESWFS
AFCCarmen
Vivace
Constellation/VRASSIAP
ACSMCR
VAP
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implementationsreverberation generation
rege
nera
tion
allp
ass
FIR
conv
olut
ion
MCR XLARES X
ACS XSIAP X
Carmen X Constellation X ? ?
Vivace XVAP X X
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implementationssignal pick-up
dire
ct
inte
rmed
iate
reve
rb
no.m
icr.
MCR X largeLARES X small
ACS X mediumSIAP X small
Carmen X medium/large Constellation X large
Vivace X smallVAP X medium/large
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implementationsearly reflection control
MCR noLARES limited
ACS yesSIAP yes
Carmen no Constellation yes
Vivace yesVAP no
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implementationsdirection
MCR noLARES yes
ACS yesSIAP yes
Carmen no Constellation ?
Vivace yesVAP limited
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implementationsgain
MCR proportional to RT60LARES largely indep. of RT
ACS largely indep. of RTSIAP largely indep. of RT
Carmen proportional to RT60 Constellation partly proportional to RT60
Vivace largely indep. of RTVAP partly proportional to RT60
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implementationsmicr. - speaker relation
MCR distantLARES distant
ACS distantSIAP distant
Carmen close Constellation distant
Vivace distantVAP close
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implementationsdecorrelation
MCR microphone speaker distanceLARES time variant
ACS time variantSIAP time invariant
Carmen time variant Constellation ?
Vivace time variantVAP time invariant
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summary
• regeneration systemsoffer good reverberation,essentially RT variation only
• in-line systemsearly reflection manipulation,RT quality dependent on the reverberator
• microphone configurationhas significant influence on enhancementcapabilities
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Remember
• there is more to acoustics than justRT60
• acoustics should not be noticed
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worth reading
Design Criteria for Acoustic EnhancementSystems
Ben Kok, Wim Prinssen6th ICSV, Copenhagen, July 1999
Variable Acoustics means Variation ofReverberation Time – does it?
Ben KokNAG-DAGA, Rotterdam, March 2009
AES 59th Conference – July 2015Acoustic Enhancement | 25
THANK YOU
[email protected]. benkok.com
www.linkedin.com/in/benkok
