Audiorium Acousics 11, Dublin Diffusion in Concer halls analyzed as a funcion of ime during he decay process Claus Lynge Chrisensen & Jens Holger Rindel Odeon A/S, Lyngby, Denmark
Agenda Why invesigae diffusiviy? Direcional Diffusion and Seady Sae Diffusiviy Defining he Dynamic Diffusion Curve DDC Normalising he DDC Typical feaures of he DDC DDC in models of 1 concer halls DDC as a funcion of disance in halls DDC and fluer echo Conclusions Audiorium Acousics 11
Moivaion, why invesigae diffusiviy? Diffusiviy is assumed o be imporan for he qualiy of concer halls Effors are pu ino promoing diffuse reflecions; making surfaces scaer sound shape of geomery disribuion of maerials Therefore we should undersand beer how given designs affec diffusiviy in rooms. Audiorium Acousics 11 3
Seady Sae Diffusiviy Thiele 1953 defined Direcional Diffusion d in % as d = 1 µ % µ = E E I % where E is sound energy and I is sound inensiy Direcional Diffusion is usually close o %, so insead we may prefer o define Seady Sae Diffusiviy in db as: D ss = log E log I [db] Noe! I = I + I + I x x z Audiorium Acousics 11
Seady Sae Diffusiviy Example on Dss a differen locaions Diffusiviyss db a Hz >= 11, Receiver in side gallery wih no visible no sigh,5 9, Odeon 195-11 Licensed o: License informaion /dongle unavailable a sar up!,9 19. db@hz P1,1 7,3,5 5, Receiver a floor. db@hz,9, 3,, <=, Audiorium Acousics 11 5
Dynamic Diffusiviy Curve DDC energy and inensiy curves Backwards inegraed squared impulse response curve = = E = log E d [ db] n n Backwards inegraed inensiy curve = n = n = n I x d + I y d + I z d = = = I = log n Audiorium Acousics 11
Dynamic Diffusiviy Curve DDC example; energy and inensiy curves Schröder curve Backwards inegraed Inensiy curve Dss SPL db 5-5 - Decay curves a Hz, T3=3, Zoomed decay T,57, -1,35=,9 s DDCn b b E, Simulaed E, Inegraed E, Correced I, Simulaed I, Inegraed -15 - -5,,,, 1 Time seconds rel. direc sound 1, 1, Audiorium Acousics 11 7
Dynamic Diffusiviy Curve DDC DDC is he difference beween energy and inensiy curves [db] log log = = = = = + + = = n n n n d I d I d I d E n I n E n DDC Audiorium Acousics 11 [db] log = = = + + z y x d I d I d I
Comparing DDC for rooms wih differen T3 Box shaped room 1 x 1 x 1 1 P1 Diffusiviy db 1 1 1 1,5 Dynamic diffusiviy curves 1 1,5,5 3 3,5 Time seconds rel. direc sound,5 b b b b b b b b T3=3.s@ Hz All hard surfaces Low scaering DDC -3 Hz DDC -15 Hz DDC -5 Hz DDC -5 Hz DDC - Hz DDC - Hz DDC - Hz DDC - Hz DDC fi -3 Hz DDC fi -15 Hz DDC fi -5 Hz DDC fi -5 Hz DDC fi - Hz DDC fi - Hz DDC fi - Hz DDC fi - Hz Diffusiviy db 1 1 1 1,5 Dynamic diffusiviy curves 1 1,5,5 3 3,5 Time seconds rel. direc sound,5 b b b b b b b b DDC -3 Hz DDC -15 Hz DDC -5 Hz DDC -5 Hz DDC - Hz DDC - Hz DDC - Hz DDC - Hz DDC fi -3 Hz DDC fi -15 Hz DDC fi -5 Hz DDC fi -5 Hz DDC fi - Hz DDC fi - Hz DDC fi - Hz DDC fi - Hz T3=1.5s@ Hz hard surfaces+absorbing ceiling High scaering Audiorium Acousics 11 9
Normalising DDC Use Schröder curve for normalizaion Subsiue ime axis wih decay [db] -1-1 - - Decay curves a Hz, T3=3, Zoomed decay T-15,9, -7,37=3,5 s b E, Simulaed E, Inegraed E, Correced I, Simulaed I, Inegraed SPL db - - - -3-3,1,,3, Time seconds rel. direc sound,5, Audiorium Acousics 11
Normalising DDC Diffusiviy db Dynamic diffusiviy curves 1 1 1 1-5 - -15 - -5-3 -35 - Decay db b b b DDC -3 Hz DDC -15 Hz DDC -5 Hz 1 DDC -5 Hz 1 DDC - Hz DDC - Hz 1 Diffusiviy db DDC - Hz 1 DDC - Hz DDC fi -3 Hz DDC fi -15 Hz DDC fi -5 Hz DDC fi -5 Hz Dynamic diffusiviy curves DDC fi - Hz DDC fi - Hz DDC fi - Hz -5 - -15 - -5-3 -35 - DDC fi - Hz Decay db b b b DDC -3 Hz DDC -15 Hz DDC -5 Hz DDC -5 Hz DDC - Hz DDC - Hz DDC - Hz DDC - Hz DDC fi -3 Hz DDC fi -15 Hz DDC fi -5 Hz DDC fi -5 Hz DDC fi - Hz DDC fi - Hz DDC fi - Hz DDC fi - Hz T3=3.s@ Hz All hard surfaces Low scaering T3=1.5s@ Hz hard surfaces+absorbing ceiling High scaering Audiorium Acousics 11 11
Typical feaures of DDC Iniial value Dss is lower ha laer values A peak appears wihin he firs 5 o db DDC reaches is plaeau level afer some 5 o db decay The plaeau can have ripples e.g. in case of a fluer echo Audiorium Acousics 11 1
1 Concer halls models Source mid sage receiver mid-parerre Dss, Peak and Plaeau levels
Two examples for comparison
DiffusiviyDss Boson Symphony Hall Floor level, only 3 meres Diffusiviyoal db a Hz >= 9,9,9 5 meres 15 5 P1, 7,5,,1 5,,7, 3,3, 1,9 1,,5 Audiorium Acousics 11 15 <=,1
Dss and Plaeau levels as a funcion of disance Boson Symphony Hall 1 Diffusiv viy db Dss db Plaeau db, 11, 1, 17,, 3,, 9, 3, 35, 3, 1, Disance Source-Receiver in meres Audiorium Acousics 11 1
DDC variaion wih disance in BSH Dynamic diffusiviy curves 35 meres 5 15 5 3 meres 15 P1 1 11 9 7 5 3 1 5 Diffusiviy db 1 1 1 1-5 - -15 - -5-3 -35 Decay db Dynamic diffusiviy curves Diffusiviy db 1 1 Audiorium Acousics 11 Diffusiviy db 1 1 1 1 1 1 R1 R5-5 - -15 - -5-3 -35 - Decay db Dynamic diffusiviy curves R9-5 - -15 - -5-3 -35 - Decay db b b b b b b b b b b b b DDC -3 Hz DDC -15 Hz DDC -5 Hz DDC -5 Hz DDC - Hz DDC - Hz DDC - Hz DDC - Hz DDC fi -3 Hz DDC fi -15 Hz DDC fi -5 Hz DDC fi -5 Hz DDC fi - Hz DDC fi - Hz DDC fi - Hz DDC fi - Hz DDC -3 Hz DDC -15 Hz DDC -5 Hz DDC -5 Hz DDC - Hz DDC - Hz DDC - Hz DDC - Hz DDC fi -3 Hz DDC fi -15 Hz DDC fi -5 Hz DDC fi -5 Hz DDC fi - Hz DDC fi - Hz DDC fi - Hz DDC fi - Hz DDC -3 Hz DDC -15 Hz DDC -5 Hz DDC -5 Hz DDC - Hz DDC - Hz DDC - Hz DDC - Hz DDC fi -3 Hz DDC fi -15 Hz DDC fi -5 Hz DDC fi -5 Hz DDC fi - Hz DDC fi - Hz DDC fi - Hz DDC fi - Hz 17
DiffusiviyDss Royal Fesival Hall Floor level, only 3 5 meres Diffusiviyoal db a Hz >= 9,9,9 meres P1, 7,5,,1 5,,7, 3,3, 1,9 1,,5 Odeon 195-11 Licensed o: Odeon Audiorium A/S Acousics 11 1 <=,1
Dss and Plaeau levels as a funcion of disance Royal Fesival Hall 1 Diffusivi y db Dss db Plaeau db, 9, 1, 15, 1, 1,, 7, 3, 33, 3, Disance Source-Receiver in meres Audiorium Acousics 11 19
DDC variaion wih disance in RFH 5 5 meres 5 15 5 3 35 3 meres 5 P1 15 11 9 7 5 3 1 5 Audiorium Acousics 11 Diffusiviy db 1 1 1 1 Dynamic diffusiviy curves -5 - -15 - -5-3 -35 - Decay db Dynamic diffusiviy curves Diffusiviy db 1 1 1 1 R1 R5-5 - -15 - -5-3 -35 - Decay db Dynamic diffusiviy curves Diffusiviy db 1 1 1 1 R9-5 - -15 - -5-3 -35 - Decay db b b b b b b b b b b b b DDC -3 Hz DDC -15 Hz DDC -5 Hz DDC -5 Hz DDC - Hz DDC - Hz DDC - Hz DDC - Hz DDC fi -3 Hz DDC fi -15 Hz DDC fi -5 Hz DDC fi -5 Hz DDC fi - Hz DDC fi - Hz DDC fi - Hz DDC fi - Hz DDC -3 Hz DDC -15 Hz DDC -5 Hz DDC -5 Hz DDC - Hz DDC - Hz DDC - Hz DDC - Hz DDC fi -3 Hz DDC fi -15 Hz DDC fi -5 Hz DDC fi -5 Hz DDC fi - Hz DDC fi - Hz DDC fi - Hz DDC fi - Hz DDC -3 Hz DDC -15 Hz DDC -5 Hz DDC -5 Hz DDC - Hz DDC - Hz DDC - Hz DDC - Hz DDC fi -3 Hz DDC fi -15 Hz DDC fi -5 Hz DDC fi -5 Hz DDC fi - Hz DDC fi - Hz DDC fi - Hz DDC fi - Hz
Queen s Hall, Copenhagen DDC and Fluer Echo reflecor panels iled slighly inwards creaing a fluer echo P1 1 Dynamic diffusiviy curves Source: 1 Surface: *Receiver* Refl.: Pah <m>:,5 Time <ms>: 77 Diffusiviy db 13 1 11 9 7 5 3 1,5 1 1,5,5 Time seconds rel. direc sound 3 b b b b b b b b DDC -3 Hz DDC -15 Hz DDC -5 Hz DDC -5 Hz DDC - Hz DDC - Hz DDC - Hz DDC - Hz DDC fi -3 Hz DDC fi -15 Hz DDC fi -5 Hz DDC fi -5 Hz DDC fi - Hz DDC fi - Hz DDC fi - Hz DDC fi - Hz Audiorium Acousics 11 1
Queen s Hall, Copenhagen DDC and Fluer Echo reflecor panels iled slighly inwards creaing a fluer echo P1 1 Dynamic diffusiviy curves Source: 1 Surface: *Receiver* Refl.: Pah <m>:,5 Time <ms>: 77 1 1,5,5 Time seconds rel. direc sound Diffusiviy db 13 1 11 9 7 5 3 1,5 1 1,5,5 Time seconds rel. direc sound 3 b b b b b b b b DDC -3 Hz DDC -15 Hz DDC -5 Hz DDC -5 Hz DDC - Hz DDC - Hz DDC - Hz DDC - Hz DDC fi -3 Hz DDC fi -15 Hz DDC fi -5 Hz DDC fi -5 Hz DDC fi - Hz DDC fi - Hz DDC fi - Hz DDC fi - Hz Audiorium Acousics 11
DDC and fluer echo Dynamic diffusiviy curves Before reamen wih scaering surfaces Diffusiviy db 1 1-5 - -15 - -5-3 -35 - Decay db b b b b b b b b b DDC -3 Hz DDC -15 Hz DDC -5 Hz DDC -5 Hz DDC - Hz DDC - Hz DDC - Hz DDC - Hz DDC fi -3 Hz DDC fi -15 Hz DDC fi -5 Hz DDC fi -5 Hz DDC fi - Hz Afer reamen wih scaering surfaces Diffusiviy db 1 1 Dynamic diffusiviy curves -5 - -15 - -5-3 -35 - Decay db DDC -3 Hz Audiorium Acousics 11 3 b b b b b b b b b DDC -15 Hz DDC -5 Hz DDC -5 Hz DDC - Hz DDC - Hz DDC - Hz DDC - Hz DDC fi -3 Hz DDC fi -15 Hz DDC fi -5 Hz DDC fi -5 Hz DDC fi - Hz
Conclusions Dynamic Diffusion Curve DDC is suggesed for invesigaing dynamic behavior of diffusion during decay Feaures for rooms wihou echoes; Sars wih Seady Sae Diffusion in audioria -7 db, Peak value ypically wihin firs 5- db of decay Plaeau level rev. diffusion in audioria 5-1 db Feaures for rooms wih echo problems, e.g. fluer echo; Ripples xx db? Furher research, opimum values, JND s, beer ools han DDC?, exrac oher informaion from he DDC ec Audiorium Acousics 11
Example Inegraed energy and inensiy curves Schröder curve Dss Backwards inegraed Inensiy curve SPL db -15 - -5-3 -35 - -5 Decay curves a Hz, T3=3, Zoomed decay T-15,9, -7,39=3, s DDCn b b b b b E, Simulaed E, Inegraed E, Correced I, Simulaed I, Inegraed -5-55,,,, 1 1, Time seconds rel. direc sound 1, 1, Audiorium Acousics 11 5
Inegraed energy and inensiy curves 5-5 - Decay curves a Hz, T3=3, s a Hz b b b b b E, Simulaed E, Inegraed E, Correced I, Simulaed I, Inegraed SPL db -15 - -5-3 -35 - -5,5 1 1,5,5 Time seconds rel. direc sound 3 Audiorium Acousics 11