Acoustic!characterization!of!the!Usina!del!Arte! … · 22nd!International!Congress!on!Acoustics,!ICA!2016! Buenos!Aires!–!5!to!9!September,!2016! !!!!! (Acoustics(for(the(21st(Century…

!Buenos!Aires!–!5!to!9!September,!2016!Acoustics(for(the(21st(Century…(

PROCEEDINGS!of!the!22nd!International!Congress!on!Acoustics!

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Concert!Hall!Acoustics:!Paper!ICA2016J166!

Acoustic!characterization!of!the!Usina!del!Arte!Symphony!Hall!

Leandro!Rodiño(a),!Alejandro!Bidondo(b),!Nahuel!Cacavelos(c)!(a)!Universidad!Nacional!de!Tres!de!Febrero,!Argentina,[email protected]!!(b)!Universidad!Nacional!de!Tres!de!Febrero,!Argentina,[email protected]!!(c)!Universidad!Nacional!de!Tres!de!Febrero,!Argentina,[email protected]!!

Abstract!

The!old! industrial! building! “Usina!Don!Pedro!de!Mendoza”!was! for! 80! years!one!of! the!most!important!electric!power!stations!of!Buenos!Aires!city.!In!the!late!90s!the!building!was!closed!and!abandoned!until!10!years!later,!when!it!was!redesigned!as!an!arts!center.!This!paper!presents!a!historical!and!architectural!review!as!well!as!an!acoustic!characterization!of!the!new!Usina!del!Arte!Symphony!Hall,!the!main!concert!hall!of!the!city!and!the!definitive!host!of!the!Symphonic!and!Philharmonic!National!orchestras.!The!equipment!and!protocols!are!carried!out!according!to!ISO!3382!in!order!to!obtain!multiple!impulse!responses,!including!monoaural,!binaural!and!3D!sound!field!recordings.!The!acoustic!parameters!evaluated!are!RT30,!EDT,!D50,!C80,!STI,!RaSTI,!IACC!and! background! noise! (NC! curve),! including! 3D! impulse! response! mapping.! The! study! also!includes!an!objective!evaluation!of!its!sound!field!diffusivity!using!the!SFDC!(sound!field!diffusion!coefficient).!

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Keywords:!acoustical!parameters,!concert!hall,!symphony!hall! !

!22nd!International!Congress!on!Acoustics,!ICA!2016!Buenos!Aires!–!5!to!9!September,!2016! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!(

Acoustics(for(the(21st(Century…!! ! !

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Acoustic!characterization!of!the!Usina!del!Arte!Symphony!Hall!

1! Introduction!1.1! Historical!review!In!1914,!the!Italo\Argentina!Electricity!company!started!the!construction!of!its!main!headquarter!in!La!Boca!neighbourhood!in!Buenos!Aires,!Argentina.!This!new!building!of!approximately!7500!m2!was!intended!to!provide!electricity!to!the!whole!city.!About!1916!it!opened!its!doors!with!the!name!of!“Usina!Don!Pedro!de!Mendoza”.!The!main!architect!and!designer!of!the!original!project!was!the!italian!Giovanni!Chiogna!while!the!constructors!were!Martignone!and!Sons.!In!1919!and!1921! respectively! the!building!had!upgrades! in!order! to!enlarge! its!electrical!energy!providing!capacity.

In!the!middle!90´s,!during!a!strong!public!privatization!process,!the!Usina!was!abandoned!and!it!became! ruins.! Ten! years! later,! the! national! and! city! government! of! Buenos!Aires! decided! to!recover!the!building!and!to!locate!there!a!new!arts!center!initially!called!¨Usina!de!las!Ideas¨.!The!entire!project!included!a!symphony!hall,!a!chamber!hall,!a!rehearsal!hall,!a!foyer!and!several!arts!exposition!rooms.!It!was!divided!in!3!stages!of!work,!the!first!being!inaugurated!on!July!14th,!2011!with!the!final!name!of!“Usina!del!Arte”!(Arts!Plant)!as!can!be!seen!in!Figure!1.!

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!Figure!1.!Usina!del!Arte!exterior!façade.

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The!façade!of!the!building!remains!as!the!original!design!with!a!strong!Florentine!Renaissance!style! that! refers! to! the! northern! Italy.! The! acoustics! of! the! Symphony!Hall! were! studied! and!designed!by!the!engineers!Rafael!Sánchez!Quintana!and!Gustavo!Basso.!It!was!intended!to!keep!the!original!industrial!style!as!the!masonry!walls!were!conserved.!The!floors,!the!mobile!ceiling!



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structure!and!the!lateral!diffusers!were!all!of!Güatambu!plywood.!In!Figure!2!can!be!seen!a!lateral!diffuser!of!a!repeated!sequence!of!QRD7.!

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!Figure!2.!Repeated!sequences!of!one!dimensional!QRD7!Schroeder!diffuser!in!the!lateral!

walls!of!the!hall. !

With!a!volume!of!15.700m3!the!hall!has!a!total!of!1200!seats!distributed!in!3!floor!of!boxes,!trays!and!side!Pullman.!The!stage!area!is!193!m2!and!the!total!audience!area!is!817!m2.!Figure!3!shows!the!auditorium!from!a!musician's!perspective!at!the!stage.!

! !Figure!3.!Stage!view!of!the!Symphonic!Hall.



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2! Procedure!2.1! Equipment! All!the!equipment!and!the!procedure!of!the!measurement!was!carried!out!according!to!ISO!3382![1].! The! instruments! used! included:! 2! Svantek! 959! sound! level! meters,! 4! Earthworks! M50!omnidirectional!microphones,!an!Outline!dodecahedron!omnidirectional!source,!a!Kemar!dummy!head!with!pinnae!simulator,!a!Soundfield!SPS200!microphone,!a!Focusrite!Scarlett!8i6!external!sound!card!and!a!Macbook!with!Aurora!module!running!within!Audacity.!All!microphones!were!located!at!all! receiver!positions.!All! instruments!were!previously!calibrated!with!a!94!dB!1!kHz!tone!generated!by!a!Svantek!SV31!acoustic!calibrator.!

2.2! !Methodology!The!measurements! took! place! on! June! 2nd! between! 9! and! 18:00! hs.! Background! noise!was!measured!with!the!sound!level!meter!at!the!early!beginning!of!the!experiment!in!10!physical!points!inside!the!room!in!Slow!mode!with!30!seconds!integration!interval.!In!order!to!obtain!the!impulse!responses!of!the!hall,!a!50!second!logarithmic!sine!sweep!(LSS)!from!40!Hz!to!16!kHz!at!16!bits!48.000!kHz!sample!rate!and!its!inverse!filter!were!generated!for!reproducing,!recording!and!later!de\convolution!and!post!processing![2].!It!was!assured!a!minimum!signal!to!noise!ratio!of!30!dB!for!all!frequency!bands.!A!combination!of!2!sound!source!positions!in!the!stage!and!5!receiver!positions!in!the!audience!area!were!used.!

The!impulse!responses!obtained!by!the!dummy!head!were!used!to!calculate!the!IACC!full!while!the!ones!obtained!with!the!omnidirectional!microphones!were!used!for!the!acoustical!parameters!including!the!sound!field!diffusion!coefficient!(SFDC)!estimator!calculation![3]!over!third!octave!bands!from!250!to!8!kHz.!Results!are!in!Gaussian!white!noise!units!(GWNu).!All!SFDC!values!used!Ct\r!as!tsplit! for!separating!the!physical!early! from!the! late!sound!field.!Also,! the!relative!crossover!times,!Ct\r![4],!were!calculated!for!all!5!receiver!positions.!All!average!results!are!shown!in!Table!1.!

With!the!responses!obtained!by!the!Soundfield!microphone,!the!3D!impulse!response!could!be!post!processed.!The!analysis!of!impulse!responses!in!three!dimensions!represents!a!novel!and!useful!tool!for!the!study!of!concert!halls.!For!this!reason,!analysis!of!impulse!responses!in!3D!was!performed!using!the!technique!of! interpretation!developed!by!Cacavelos!et#al! [5].!For!analysis!settings! 1! ms! time! windows! were! used! in! order! to! achieve! greater! accuracy,! thus! avoiding!overlapping!reflections!in!a!single!window.!A!low\pass!filter!at!5!kHz!was!applied!to!the!signal!in!order!to!avoid!phase!distortion.!The!choice!of!the!filter!cutoff!frequency!is!given!by!the!distance!between!the!tetrahedral!microphone!capsules!used!in!the!measurement.!The!number!of!vectors!shown!was!rigged!to!256!in!order!to!achieve!clarity!in!the!resulting!graphs.!

The!displayed!acoustical!parameters!are!EDT,!RT30,!C80,!D50,!IACC!Full,!STI,!RaSTI,!AlCons%,!SFDC! (Early,! Late! and! Total)! and! Ct\r.! The! numerical! method! for! calculating! the! first! eigth!parameters! was! examined! and! explained! in! detail! by! Leo! Beranek! [6].! All! the! results! were!



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averaged!among!all!the!obtained!samples!and!the!standard!deviation!of!the!mean!was!calculated!and! displayed.! Given! the! magnitude! of! the! obtained! results,! the! computational! error! of! the!calculation![7]!was!not!taken!into!account.!

3! Results!3.1! Background!noise!The!average!background!noise!measured!by!third!octave!band!was!31,5!dBA.!As!can!be!seen!in!the!Figure!4!it!corresponds!with!a!NC\20!curve!according!to!ANSI!S12.2![8].!

!Figure!4.!Average!background!noise!over!octave!frequency!bands.!

3.2! Acoustical!parameters!

Figure!5.!Average!early!decay!time!over!third!octave!bands!and!its!standard!deviation.!



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! Figure!6.!Average!RT30!(reverberation!time)!over!third!octave!frequency!bands!and!its!standard!deviation.!

!Figure!7.!Average!C80!(clarity)!over!third!octave!bands!and!its!standard!deviation.!

!Figure!8.!Average!D50!(definition)!over!third!octave!frequency!bands!and!its!standard!

deviation.!



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Figure!9.!Average!interJaural!cross!correlation!over!octave!frequency!bands!and!its!

standard!deviation.!

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Figure!10.!Average!values!for!SFDC!EARLY,!LATE!and!TOTAL!over!third!octave!frequency!bands!and!its!standard!deviation.!

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!Table!1.!Average!values!for!Crossover!time,!SFDC!EARLY,!LATE!and!TOTAL.

CtJr![ms] SFDC!EARLY![GWNu] SFDC!LATE![GWNu] SFDC!TOTAL![GWNu]

56.7 0.86 1.07 0.69

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Table!2.!Average!speech!intelligibility!and!articulation!loss!results!and!its!standard!deviation.!

!! Average!Final! Standard!Deviation!

STI! 0,48! 0,08!AlCons![%]! 12,75! 0,11!STI!(Male)! 0,47! 0,09!STI!(Female)! 0,47! 0,1!RaSTI! 0,44! 0,13!

3.3! IR!mapping!In! Figure! 10! a! 3D! RIRs! single!measurement! point! is! shown! on! four! views! corresponding! to!axonometric!main!view!(Standard!view)!and!three!orthogonal!planes!including!the!point!of!origin!(Top,!Front!and!Lateral!view).!In!this!example!it!is!possible!to!observe!that!the!greatest!energy!concentration!comes!from!the!rear!of!the!microphone!in!the!three!planes!represented.!In!temporal!terms,!side!components!within!the!first!50!ms!and!rear!energy!content!in!the!150!ms!of!the!direct!sound!are!observed.!This!way!provenances!of!the!early!and!late!reflections!can!be!analyzed!of!the!impulse!response!measurement.!

!Figure!10.!3D!impulse!response!of!a!single!measurement!point!of!the!hall.!



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3D!RIR!display!joins!energy,!3D!image!source!direction,!frequency!and!temporal!information.!3D!RIR!are!composed!by!vectors!with!same!origin!but!different!directions!and!colors.!Each!vector!is!the!result!of!an!energy!calculation!using!a!temporal!integration!window!(in!this!case!was!set!to!1!ms).!The!vector’s!length!represents!its!magnitude.!All!magnitudes!are!direct!sound!normalized.!The! vector’s! color! is! the! temporal! separation! from! the! direct! sound! (from! red! to! blue),! in!milliseconds.!With!3D!RIRs!and!Ct\r,! early!and! late!physical! sound! field!provenances!can!be!clearly!identified!and!studied.!!

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Figure!11.!2D!impulse!response!mapping!over!the!symphony!hall!plan.!

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4! Concluding!remarks!With!the!aim!of!describing!acoustically!the!Usina!del!Arte!Symphony!Hall,!a!series!of!acoustical!descriptors!were!post\processed!from!registered!impulse!responses!and!displayed.!SFDC,!Ct\r!and!3D!impulse!responses!results!were!included.!The!authors!recommend!the!latter!to!become!included!in!every!acoustic!analysis!in!order!to!characterize!music!halls,!as!they!bring!information!about! the! reverberation! texture,! the! instant! when! the! room! becomes! memoryless! and! the!directions!arrivals,!respectively.!

Acknowledgments!This!research!was!supported!by!UNTREF!University,!and!their!main!authorities,!Jozami,!A.!and!Kaufmann,!M.,!Rector!and!Vice!Rector!respectively.!Also!we!have!to!thank!Prof.!Joaquín!Mansilla,!Prof.!Shin\ichi!Sato!and!Students!from!UNTREF’s!2014!Acoustic!Instruments!and!Measurements!lecture,!for!their!help!and!collaboration.!!



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A!special!acknowledgment!should!be!made!to!Alberto!Haedo,!who!provided!an!insight!overview!of!the!construction!and!modeling!project.

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References![1]! !ISO,!International!Standard!ISO!3382:!Acoustics#–#Measurement#of#rooms#acoustic#parameters,!2012.!

[2]! !Farina,!A.!Advancements! in! impulse! response!measurements! by! sine! sweeps,!Audio#Engineering#Society#122nd#convention,!Vienna,!Austria,!May!5\9,!2007.!

[3]! !Bidondo,!A.r! Vázquez,!S.r! Vázquez,! J.r!Heinze,!G.r! Arouxet,!M.!Measuring!Sound!Field!Diffusion:!SFDC.!139th# Audio# Engineering# Society#Convention.!October! 31! –!November! 1st.! NY.!USA.! 2015.!Convention!Paper!9462.!

[4]! Bidondo,!A.r!Vázquez,!S.r!Vázquez,!J.r!Heinze,!G.r!Arouxet,!M.!A!new!and!simple!method!to!define!the!time! limit! between! the! early! and! late! sound! fields.! 141nd# Audio# Engineering# Society# Convention.!September!29th!–!October!2nd.!L.A.!USA.!2016.!

[5]! Cacavelos!N.r!Bonelli!A.r!Bidondo!A.r!Development!of!a!3D!impulse!response!interpretation!algorithm.!22nd!International!Congress!on!Acoustics,!Buenos!Aires,!Argentina,!2016.!

[6]! Beranek,!L.!Concert#Halls#and#Opera#Houses:#Music,#Acoustics,#and#Architecture.!Springer,!NY!(USA),!2nd!edition,!2004.! !

[7]! Mansilla,!J.r!Sato,!S.r!Rodiño,!L.r!Arias,!A.r!Masson,!F.r!Calderón,!I.r!Comparison!of!room!acoustic!parameters! calculated! by! different! types! of! software.! Internoise# 2015# convention,! San! Francisco,!United!States!of!America,!9\12!August,!2015.!

[8]! !ANSI/ASA!S12.2,!Criteria#for#Evaluating#Room#Noise,!United!States!of!America,!2008.!

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Documents

Acoustic!characterization!of!the!Usina!del!Arte! … · 22nd!International!Congress!on!Acoustics,!ICA!2016! Buenos!Aires!–!5!to!9!September,!2016! !!!!! (Acoustics(for(the(21st(Century…