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THREE-DIMENSIONAL ACOUSTIC DISPLAYS IN A MUSEUM EMPLOYING WFS (WAVE FIELD SYNTHESIS)

AND HOA (HIGH ORDER AMBISONICS)

Angelo Farina1,2, Andrea Capra1,2, Paolo Martignon1,4, Simone Fontana1,2,3, Fons Adriaensen1, Paolo Galaverna1 and Dave Malham5

1 LAE - Laboratory for Acoustics and Electroacoustics, Parma, ITALY, HTTP://www.laegroup.org

2 University of Parma, Industrial Engineering Dept., Parma, ITALY

3 Ecole Nationale Superieure de Telecommunications (ENST), Paris, FRANCE

4 University of Ferrara, LAV (Laboratory for Acoustics and Vibrations) Ferrara, ITALY 5 Music Research Centre, Department of Music, The University of York, UK

ICSV14

Cairns • Australia

9-12 July, 2007

(2)

The “Casa del Suono”

• It was born thanks to the cooperation of University of

Parma, Comune of Parma, and with funds (approximately 2 million Euros) provided by Casa della Musica, Italian

Governement and Cariparma Foundation

• The institutional goal is to display the famous Patanè’s Collection of vintage grammophones and radios, made available by CNIT (National Italian Consortium for

Telecommunications)

• It is also a research lab about electroacoustics, equipped with the latest technologies for sound recording and

reproduction employing a large number of channels

Presidenza del Consiglio dei Ministri

(3)

Topics

• Restoration of the S.Elisabetta church

• Exhibit of Patanè’s Collection

• Sound system for the exhibit

• The SONIC CHANDELLIER, an innovative planar WFS installation

• 30-seats listening room (linear WFS)

• The single-seat listening room (Binaural,

Ambisonics, Ambiophonics)

(4)

The S.Elisabetta Church

A Baroque square church, with annexed rectangular chapel

(5)

The S.Elisabetta Church

The main room is characterized by a very tall dome,with a lot of light thanks to many windows; in the center of the dome

the SONIC CHANDELLIER was installed

(6)

The S.Elisabetta church

Before the restoration the building was in miserable conditions

(7)

The S.Elisabetta church

Advanced restoration techniques revamped the original beauty

(8)

The S.Elisabetta church

However, these restoration and consolidation techniques caused the

acoustical behaviour of the church to worsten significantly, raising the

reverberation time of the empty room from 2.3 s to more than 4.0 s

(9)

The exhibit

6 circular niches in glass and steel, located in the 6 chapels of the main

church, contain the major part of the “pieces” being exposed

(10)

The exhibit

In the rear chapel, the two “surround” listening rooms are located

(11)

Patanè’s Collection

• The collection was donated to CNIT by don

Giuseppe Patanè, a priest and a collector, who employed his entire, long life for searching,

purchasing and repairing valuable pieces.

• The collections contains approximately 400 pieces, ranging from the first phonographs, to

Galen radios and extends to domestic and military radios of 20’s, 30’s, 40’s up to the first years after WWII. All pieces have been carefully maintained and serviced, most of them are working as new....

• There are also some particularly rare pieces, such as a cryptographic “Enigma” machine, employed by the German army for transmitting encoded

informations during WWII.

(12)

Patanè’s Collection

• Some samples from the collection

(13)

Patanè’s Collection

• Some samples from the collection

(14)

Patanè’s Collection

• Some samples from the collection

(15)

Touch screen

Speakers

Speaker

Exhibit’s sound system

(16)

Focus

S P E A K E R

Absorbtion

Exhibit’s sound system

Two vertical 13-speakers line-arrays are employed. A DSP unit focalizes

the sound downwards, where absorptive “sound traps” are located, for

avoiding to spread the sound all around the church

(17)

8 ch. DSP 8 ch. AMP

Player

Listener Delays ..

DSP control of line arrays

QSC 8-channels amplifier + BASIS

DSP controller / Cobranet interface

(18)

DSP control of line arrays

(19)

The Niches

Niche n. 1 - PHONOGRAPHS AND GRAMMOPHONS

1897-1923

(20)

The Niches

Niche n. 2 - RADIO

1921-1926

(21)

The Niches

Niche n. 3 - RADIO and GRAMMOPHONS

1926-1929

(22)

The Niches

Niche n. 4 - RADIO

1930-1935

(23)

The Niches

Nicchia n. 5 - RADIO AND RADIOGRAMMOPHONS

1935-1954

(24)

The Niches

Nicchia n. 6 - RADIO, TURNTABLES, AMPLIFIERS, STEREO

1950 - 2007

(25)

convex focus concave Absorption

1 kHz

2 kHz 500 Hz

The “Sonic Chandellier”

(26)

Design and Construction

(27)

Special 32 Ohm model by Ciare

Design and Construction

(28)

Installation

(29)

Hardware (computer, converters, amplifiers)

Computer Linux multiprocessor

Interface PCI->MADI (RME)

Interface MADI->ADAT (RME)

8 x converters ADAT 8ch. (Behringer)

8 x amplifiers 8ch. (QSC mod. 1608)

(30)

Hardware (computer, converters, amplifiers)

64 output channels

(31)

Software structure on Linux PC

“WFS Focus”

Software (runtime controlled multichannel

processor)

to the feeding system...

Audio Application

+

WFS plug-in

Audio 64 ch

(MADI bus) Audio

Mono 1

OSC

WFS GUI

OSC MIDI or

OSC controller

External Audio

MIDI or OSC

Audio Mono 2

Software

(32)

MIDI or OSC

“WFS Focus” structure

Software

(33)

Listening rooms

(34)

Listening rooms

• La sala bianca ospita sino a 30 ascoltatori, ed è dotata di

un sistema surround planare tipo WFS (192 altoparlanti)

(35)

30-seats room (“sala Bianca”)

• 176 loudspeakers are incorporated in the perimetral

walls, completely surrounding the audience at ear-height

(36)

The WFS technology

• Wave Field Synthesis is a playback technique which makes use of linear loudspeaker arrays which are used for creating wavefronts

appearing to be radiated by a virtual source

• Concept: spatially sampling a wavefront

(37)

WFS applications

• WFS can generate point sources or planar sources, and

even point sources which appear to be inside the room,

in the middle of the audience area

(38)

Tecnology WFS @ IRCAM, IRT

(39)

Synthesis of a virtual environment with WFS

(40)

FREE Software for WFS

• The Linux program Wonder makes it possibile to

generate WFS signals and to move in realtime the virtual

source being synthesized

(41)

Low-cost hardware for WFS

• The cheaper solution is based on a PC containing three MADI interfaces

(64 ch. each), connected with a rack of low-cost converters (Behringer)

(42)

Single-seat room (“sala Nera”)

• This room is equipped with 26 loudspeakers

(43)

Single-seat room

• The walls are made by plywood, gypsum boards and perforated

panels with polyesther fiber wool, providing good sound insulation

and optimal control of reverberation

(44)

Single-seat room

• The sound absorbing treatment, here simulated

employing the Ramsete program, provides a value of T20

of 0.40 s at 125 Hz and even lower ar higher frequencies.

(45)

Binaural (Stereo Dipole) method

• Playback is made on 2 loudspeakers located at +/- 10°, being fed through a digital cross-talk

cancellation system

2 3

1

Original 2-channels recording of the signals coming from N sources

d1l

xr

xl

Cross-talk canceller

d1r d2l d2r

dNl dNr N

20°

(46)

Binaural (Dual Stereo Dipole)

Pro Pro : :

„„

3D sound reproduction 3D sound reproduction

„„

Cross Cross - - talk cancellation talk cancellation filters also equalize

filters also equalize perfectly loudspeaker perfectly loudspeaker

and microphones and microphones

Contro Contro : :

„„

Poor low frequencies Poor low frequencies

„„

Colouring outside the Colouring outside the

“ “ sweet spot sweet spot ” ” Schematics

Subwoofer

(47)

Ambisonics Method

Recording Processing Playback

Encoding B-Format

Decoding

Speaker-feeds

(48)

• The Soundfield (TM) microphone provides 4 signals:

1 omnidirectional (pressure, W) and 3 figure-of-8 (velocity, X, Y, Z)

Recording

(49)

Recording Encoding Processing

X Y Z W

Directional components:

velocity

Omnidirectional component : pressure

Soundfield microphone

Polar diagrams

B-FORMAT

Decoding & Playback

Recording

(50)

Recording Encoding Proccessing

0 W

X

Y

Z 1

=0,707

=cos(A)cos(E)

=sin(A)cos(E)

s(t)=

=sin(E)

*s(t)

*s(t)

*s(t)

*s(t)

2 1

2

2 + Y + Z =

X

Decoding & Playback

Encoding

(51)

⎪ ⎪

⎪ ⎪

+ +

+

=

+ +

+

=

+ +

+

=

+ +

+

=

Z k Y

k W

k X

k Z

Z k Y

k W

k X

k Y

Z k Y

k W

k X

k W

Z k Y

k W

k X

k X

44 43

42 41

34 33

32 31

24 23

22 21

14 13

12 11

' ' ' '

Recording Encoding Processing Decoding & Playback

z z

R y

R x

y

R y

R x

x w w

=

⋅ +

=

=

=

'

) cos(

) sin(

'

) sin(

) cos(

' '

) cos(

) sin(

'

) sin(

) cos(

' ' '

T z

T y

z

T z

T y

y x x

w w

⋅ +

=

=

=

=

) cos(

) sin(

' '

) sin(

) cos(

' '

T z

T x

z y y

T z

T x

x w w

⋅ +

=

=

=

=

Rotation

Tilt

Tumble

Processing

(52)

Recording Encoding Processing Decoding & Playback

Z

Y

X

Speaker i-esimo

3D decoding 2D decoding

Decoding

(53)

High Order Ambisonics (HOA)

• As a complex time-domain waveform can be though as the sum of a number of sinusoidal and cosinusoidal functions, so a complex spatial distribution around a given notional point can be expressed as the sum of a number of spherical

harmonic functions

• When the signals corresponding to spherical harmonics up to 3° order are summed with proper gains, one obtains a “virtual microphone” having a directivity pattern which can be very complex and highly directive

-0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8

0 0.5 1 1.5 2 2.5 3

dc Cos(5) Sin(5) Cos(10) Sin(10)

-1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1

0 0.5 1 1.5 2 2.5 3

Sum -20

0 0

5 10 1520 25

30 35

40 45

50 55

60 65

70 75

80 85 90 95 100 105 110 115 120 125 130 135 140 145 150 160155 170165 175 180 190185 200195 205 210 215 220 225 230 235 240 245 250 255 260 265 270 275 280 285 290

295 300

305 310

315 320

325

330335340345 350355 0

0.35 0

5 10 1520 25

30 35

40 45

50 55

60 65

70 75

80 85 90 95 100 105 110 115 120 125 130 135 140 145 150 160155 170165 175 180 190185 200195 205 210 215 220 225 230 235 240 245 250 255 260 265 270 275 280 285

290 295

300 305

310 315

320

325330335340345350355

(54)

Spherical Harmonics

(55)

3 rd -order spherical microphone

(56)

Software for Ambisonics processing

Linux - Jack: AmbiDeco decoder by Fons Adriansen (open source, free)

(57)

Software for Ambisonics processing

Windows: VST plugins by Gerzonic, Dave Malham, Bruce Wiggins (freeware)

(58)

Software for Ambisonics processing

Windows: Visual Virtual Microphone by David McGriffy (freeware)

(59)

Low-cost hardware for HOA

• Again, a PC with MADI interface is employed

Stereo-Dipoles

Ambisonics 2D / 3D

Binaural

Multicore PC

RME MADI interface

(60)

Locations of loudspeakers

Horizontal Ambisonics octagon Ambisonics 3D cube Standard Stereo

Frontal Stereo-Dipole Rear Stereo Dipole Upper Stereo Dipole

(61)

Psychoacoustics research

• Musical Food: sound quality analysis of Barilla - Mulino Bianco crackers and bread substitutes

Fette Biscottate Classiche Spianelle

(62)

Psychoacoustics research

• Listening tests with compilation of sound quality

questionnaires

(63)

Psychoacoustics research

• Principal Component Analysis and correlation among physical and perceptual paramaters

Sonoro

Silente

Crispy

Crunchy

(64)

• Definzione contenuti espositivi e coordinamento:

Alessandro Rigolli (per l'Istituzione Casa della Musica)

• Progettazione allestimento espositivo:

Dario Costi e Simona Melli architetti

• Realizzazione allestimento espositivo:

– Leonardo Laboratorio di Costruzione S.n.c. via G. Giusti, 4/a Parma – Gruppo Fallani S.r.l. via Pialoi, 100 Marcon (Ve)

– Tecno-fer S.r.l. v.le Basetti, 14 Parma

• Progettazione e realizzazione componente acustica (LAE):

– AIDA srl via G. Sicuri, 60/a Parma – Genesis via Benedetta, 83 Parma

– Audiolink via Monte Prinzera, 17 Parma

• Sistemi informatici: IT City S.p.A. via Traversetolo, 36/a Parma

• Cablaggio:

– Albacom.Amps Telecomunicazioni S.p.A.

– Guglielmo srl via Livatino 9 Reggio Emilia Aet Parma Srl via Lelio Guidotti 15/A Parma

Thanks to:

(65)

Thanks to:

• The design and construction of these sound systems have been possible thanks to:

Laboratory of Acoustics and Elettroacoustics (LAE)

www.laegroup.org

Parma

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