Paper for AMTA 08 Bucharest

1. Advanced techniques for the determination of sound spatialization in Italian Opera Theatres ENRICO REATTI, LAMBERTO TRONCHIN & VALERIO TARABUSI AMTA 08 - 24-26 June 2008 Bucharest

4. Plan It was built in the second half of the 18th century by the architect Antonio Galli Bibiena Bell shaped (no horse-shoe shape) Auditorium build with plastered bricks (no wood in the balconies) Last restoration work of 1980 brought to light traces in the plasterwork of the personalisation of the balconies.

5. Sezione longitudinale 34 m 22 m 16 m 33 m Capacity: 420 seats in the stalls 480 in the balconies Stage area: 460 m 2

6. Sezione trasversale 15,6 m Auditorium has seats in the stalls, in the four tiers of balconies and in the gallery

7. Experimental analysis Criteria for the choice of measurement positions : Good spatially distribution Research on half auditorium (symmetry hypothesis) Omni directional sources not centered to avoid focus points

8. Measurement points

9. Omni directional Array of loudspeakers Instrumentation Microphone Soundfield & Amplifier/processor Binaural Dummy Head Neumann (Senneheiser mic headset) Personal Computer P4 Software Adobe Audition Sound board ”Echo” Event

10. Measurement chain Test signal “sweep ” Sound propagation Stage complex & auditorium Acoustic Omni directional speaker Mic Soundfield Dummy Head PC & sound board

11. Data post processing audio signals (WY, XZ, Bin L/R) IMPULSE RESPONSE (IR) Impulse response (IR) Measurement in a particular seat EXPERIMENTAL MESAUREMENT Inverse filter

12. Impulse response Direct Sound Reflected Sound Sound source Receiver Direct Sound Reflected Sound

14. Acoustical parameters C80 - CLARITY INDEX D50 – DEFINITION INDEX

15. Acoustical parameters Early decay is responsible of sensation of reverberation Time necessary to the signal to decrease from -5dB to -35dB EDT – EARLY DECAY TIME T30 – REVERBERATION TIME

16. Acoustical parameters Is possible to calculate by Sounfield microphone using omni directional and Y signal Is possible to calculate by Dummy head signals (corresponding to two different ears) LF – LATERAL FRACTION IACC – INTERAURAL CROSS CORRELAION INDEX

17. Numeric Model The Ramsete calculation software, based on the pyramid tracing method (a variant of the “cone-tracing” algorithm) was used for processing.

18. 3D CAD Model A 3D cad model was made of the theatre’s auditorium and stage complex behind, using present day plan and elevation views

19. Numeric model elaboration Ramsete was run and the simulation repeated several times The associations between the properties of the materials and the flat elements (22000 flat el.) were entered and the same grid of 25 receiver points used for the experimental investigation was reconstructed. File ramsete.mat: each 3D face is part of a group and group has a set of coefficient of absorption (1/3 octave) associated

20. Numeric model elaboration Obtained a good numeric model is possible to calculate the acoustical parameters , as before, correspondent to a receiver point chosen, trough the extrapolation of his IR. Impulse response (receivers num. 5 e 8 at 125 Hz) Acoustical parameters (receivers 5 e 8)

21. Auralisation A anechoic recording of an excerpt from Torna a Surriento was processed by means of the experimentally and numerically obtained impulse response of a seat in the stalls (20d). Trough auralisation everyone can ear how the acoustic properties of the theatre change a sound reproduced in it. Experimental IR Numeric model IR Anechoic excerpt (tenor singer) Takes deconvolved with IR STOP

23. The End

24. Thank you

25. The crew Authors: Ing.Enrico Reatti Prof. Ing. Lambeto Tronchin Prof. Ing. Valerio Tarabusi Special thanks to: Dott. Ryota Shimokura Mr. Gerardo Pece Web sites: www.ciarm.ing.unibo.it www.deacustica.it AMTA 08 - 24-26 June 2008 Bucharest