Pres Wseas Amta Bucharest08
- 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
- 2. Acoustic and spatialization - Acoustic map of a typical “Italian style” opera theater Impulse responses and acoustical parameters Simulate the same space and conditions by a numeric model and obtain again IRs and acoustical parameters auralization of an anechoic excerpt like a way to compare the experimental study and the numerical one
- 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
- 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
- 13. Acoustical Parameters - Strength Strength represents amplification effect of the auditorium. Strength is correlated to Loudness and consequently to the sound quality. difference between strength measured on the stage and this one measured in the pit represents the BALANCE.
- 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
- 22. Conclusions Make an experimental analysis is useful also to do a “Backup” of the acoustic of a theatre (for ex. La fenice) Acoustic map as important as plan and elevation plan Estimate space project trough a numeric model is of great use in many different fields: from brand-new projects to restoration. Acoustic render
- 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