About REVERBDATA
REVERBDATA is an Acoustic Heritage database of significant Portuguese spaces. It contains Room Impulse Responses – RIR of spaces that are selected based on their importance from the acoustical, architectural, cultural, and functional points of view. Multi-channel RIR are being registered at several locations inside the selected spaces, processed and fed to the database, providing a GUI for navigation and for artificial reverberation generation. Using advanced and optimized measurement and processing techniques, impulse responses under different multi-channel formats are being acquired for subsequently allowing immersive and accurate sound reproduction through FFT convolution reverb. RIR databases have been developed and explored in audio and acoustics, providing a valuable collection of measured or simulated responses that almost completely describe the acoustic characteristics of different spaces.
The data is divided into architectural documentation, acoustic records with associated specific information and photographic materials. Regarding acoustic acquisitions and recordings, raw audio containing the sweeps and in situ recorded RIR is available, as well as post-processed audio containing the optimized, noise-free responses. The RIR are subdivided into two categories, the first containing the stereo and binaural responses (in 4-channel wave files) and the second containing the Ambisonics responses in formats A and B. In the latter case, the responses are available in the FUMA or ACN/AMBIX formats. Stereo-binaural responses are available normalized to the maximum value ±1 or scaled according to source-receiver distances. For some spaces, mono impulse responses acquired using ARTA software (v1. 9.7) are also available in the database. For each post-processed RIR, the main objective parameters describing the acoustic quality of the space (wideband and octave band values) are available in an associated .txt file.
What is a Room Impulse Response?
A Room Impulse Response (RIR) is like an acoustic photograph of a space. It contains the complete information on how the sound is heard and perceived inside the space due to reverberation.
Reverberation is a common auditory phenomenon experienced daily, resulting from sound interacting with the surrounding environment. This effect, that is particularly audible in enclosed spaces due to the numerous echoes arising, is often artificially incorporated into electronically recorded and produced music, as well as other media like cinema, virtual reality applications, and computer games. Using RIRs together with a technique called convolution reverb we can obtain the exact acoustic sense experienced in real spaces.
Portuguese Spaces
Acknowledgments
The authors thank all entities that have provided access to their spaces, allowing for setting up REVERBDATA.
We thank all students of Music Technologies who have participated in REVERBDATA.
IPL/IDI&CA2023/REVERBADATA_ESML
Calouste Gulbenkian Foundation
Grand Auditorium
The Grand Auditorium of the Calouste Gulbenkian Foundation in Lisbon had its inaugural concert on the 3rd of October 1969, the day after the official inauguration of this complex. With exceptional acoustics, its design and construction were aimed at hosting many cultural activities, including symphonic and choral-symphonic music, congresses and conferences, ballet, theater and cinema. The hall was designed by the Portuguese architects Alberto Pessoa, Pedro Cid e Ruy d’ Athouguia and by the British acoustician William Alexander Allen. Renovated in 2014, with ARUP as acoustic consultant, the Great Hall has a capacity for 1203 people, spread over 36 rows on 3 different levels.
Cartuxa Monastery
The project for a New Church was born with the general plan of the Monastery of D. Basílio de Faria, Prior of Vallis Misericordiae between 1613 and 1621. However, the construction of the Church was dragged into a second phase of works, as the need was imposed of the construction of the Hermitage. About a century later, in the priory of D. Luís de Brito (1716 – 1746), the economic conditions came together to allow progress with the second phase of construction of the New Monastery, largely thanks to the alms collected by Gregório dos Santos in Brazil , who began arriving in Laveiras in 1727. On March 25, 1733, a second blessing of the Church took place and the first stone of the construction was laid, in the presence of the first patriarch of Lisbon, D. Tomás de Almeida. According to some authors, the works themselves began in 1736. In that year, Frei Gregório managed to raise another 99,800 reis from benefactors in Portugal and the Monastery received a generous contribution from King D. João V for the works on the New Church.
From Guerin, A.; Marrinhas, M. L.; Bulhões, D. , “Santa Maria Vallis Misericordiae – A Cartuxa em Oeiras”, Municipality of Oeiras, Oeiras 2023.
Church
In 1746 the Church was already built and in use, with only the main chapel panel missing, and on the frontispiece the niche of Our Lady and the fires at its top, which was soon completed. The New Church is built to the south of the Hermitage and aligned with its axis, in tradition of the monastic architecture of the Order of Saint Bruno. To the west is the Small Cloister and its facilities for monastic community life. The architecture and distribution of the spaces of a Carthusian Church are at the service of a cult that obeys specific rules and statutes of the Order of St. Bruno, which is why the space presents characteristics specific to the Order.
The church, with a wide limestone facade, is topped by an image of the Virgin and Child and was built in the 18th century. Due to its excellent acoustics, this space has regularly hosted concerts by the Lisbon Metropolitan Orchestra and the Cascais and Oeiras Orchestra.
Coliseu Micaelense
Located in Ponta Delgada city, is the largest entertainment hall in the Autonomous Region of the Azores. Built in 1917, it was purchased, renovated and reopened by the Ponta Delgada City Hall in 2005. It can host a wide variety of events, including shows in a conventional auditorium and shows in a circus arena, even shows such as café-concerts, rock concerts, banquets, casino, congresses, fairs and dance balls.
Convent of Christ
The Convent of Christ is a UNESCO Heritage of Mankind monumental complex in the city of Tomar, having been continuously built between the 12th and 16th centuries. Known for its Templar history and diverse architectural styles, it is of undeniable cultural and archaeological importance.
Nowadays it is permanently open to the public and occasionally it hosts educational and artistic exhibitions as well as cultural events such as concerts and plays.
The acoustic acquisitions and records were done in the Church of the Convent (Charola – Round Church and Main Body), Main Cloister (D. João III), Refectory and Cistern (of the Crows’ Cloister), allowing for a rather complete and unique heritage preservation of the monument’s acoustics.
Charola – Round Church and Main Body (3rd Floor)
Located on the 3rd floor, the Church of the Convent of Christ is made up of the Charola (or Rotunda) and of the Main Body of the church.
The Charola dates from the 12th century and is an early Templar Romanesque fortified oratory inspired by the Temple of Jerusalem, having its capitals on the central columns and the painting on stone allusive of St. Christopher, dating also from that period. The Main Body, built in the Manueline style from 1510-15 by Diogo Arruda and João de Castilho, includes the nave, the upper choir and the lower choir, and is joined to the Charola by means of an arch opened in the walls of the old oratory. The inner drum of the Rotunda would be turned into a chancel.
Between 1510-15 King Manuel I also commissioned the decorative interior of the Church, adding stucco, carved woodwork and the fresco and secco paintings. From that period are the wooden statues in the chancel and the upper choir stalls, now gone, by the Flemish sculptor Olivier de Gand and completed by Fernão Munhoz, and also a set of monumental wooden boards executed by the royal painter Jorge Afonso. The paintings on the peripheral altars of the Charola, by Gregório Lopes (1536-38) would also be added during the 16th century, as well as the decoration on the triumphal arch by Domingos Vieira Serrão and Simão de Abreu (1592-97).
Main Cloister D. João III (1st Floor)
The Main Cloister (D. João III) is the magnum opus of the Renaissance convent built by King D. João III, outside the castle walls, and surrounding the nave with which his father, D. Manuel I, expanded the Templar church.
It is part of the group of four large cloisters around which the formal structure of convent space is based. Adjacent to the Church of the Convent, the D. João III Cloister flanks the south façade of the Manueline nave. Its design is different from the rest of Castilian convent architecture. Remade after the death of Diogo de Castilho, by Diogo de Torralva, in the Mannerist style of the Italian Cinquecento, this cloister will feature a graceful water fountain, from Fernandes Torres, fed by water from the conventual aqueduct. It is considered a masterpiece of the European Renaissance.
Refectory (1st Floor)
The Refectory, built by João de Castilho during the great campaign of King João III, was probably finished between 1535 and 1536, according to the inscriptions on the pulpits that were reserved for reading during mealtimes.
It has very interesting vaulting ribs. The antechamber served as a pantry and gave access to the kitchen. The wine and olive oil cellars lay below the refectory, as did other rooms of agricultural nature, connected to the orange grove (Friars’ Garden) and the Convent enclosure. The present arrangement of the tables was due to later work, from the time of the Missions Seminary (Seminário das Missões), 1922-92.
Cistern of the Crows’ Cloister (Basement)
The Cistern (of the Crows’ Cloister), built between 1543 and 1546 by João de Castilho, was probably used for irrigation. Castilho himself called this space the barn cloister. The Cistern has exclusive access via a small staircase, close to the door to the friars’ kitchen.
The quadrangular shaped Cistern has two double arcade galleries separated by buttresses, which rise to the 3rd register to the south and west, and coverings and supports identical to those of the Cloister of Micha. The block is surrounded by 4 bodies of 3 floors, with the south side occupied by the old granary (today the chapel), the north by the kitchen (ground floor) and the novitiate cells (1st floor) and the east side by the Refectory and the cells on the south arm of the dormitories.
Lisbon School of Education
It can be considered that the roots of Lisbon School of Education (ESELx) date back to the portuguese reign of D. Luís and the year 1862, when the Lisbon Primary Normal School was created. Installed in the Palace of the Marquises of Abrantes, in Marvila, this School admitted only male students. The Female Normal School, located in Calvário, began its activities in 1866. From 1914 the two Normal Schools merged and began to operate under a co-education regime, in its own building, located at Quinta de Morocco in Benfica, in the 1919. This is the building where the Lisbon School of Education is located today. This building has been undergoing restoration, maintenance and recovery works, which have allowed the spaces to be adapted, monetized and improved, making them more functional and consistent with the activities that the School carries out. ESELx only began its activities in 1985 with the appointment of the Installation Committee. For eight years, from 1985 to 1993, the School developed activities in the various fields of intervention assigned to it – initial, continued and specialized training; professionalization in service; research, research and development; provision of services to the community – together with the tasks inherent to the installation regime. On January 1, 1994, following the approval of the School’s statutes, the Board of Directors, elected by members of the school community, took over.
From ESELx site (“history”)
Great Hall
Located at Lisbon School of Education, has a maximum seating capacity for 300 persons and allows a variety of cultural events such as theatre, cinema, concerts, and conferences. The hall has a flat audience area, with individual chairs, and a circular shape balcony.
Lisbon School of Music
Lisbon School of Education (ESML) was created in 1983 following the reconversion of the National Conservatory, having been integrated into the Polytechnic Institute of Lisbon in 1985. ESML assumes as its mission the artistic, technical, technological and scientific training, at the highest level, of professionals in the Music area. It presents itself, on the national and international scene, as a reference school, which is based not only on its origins and the recognized quality of its international-level teaching staff, but also on the dynamics, diversity, projection and prestige of its achievements. artistic in the fields of artistic production and dissemination, teaching and research, which illustrate and embody its commitment to the constant search for excellence, openness to innovation and contemporaneity. Located on the IPL Benfica Campus, it has facilities of recognized international architectural prestige, as well as equipment suitable for its training activity. In pursuit of its mission, it promotes a teaching/learning environment equipped with the highest standards of demand and quality, guiding students towards their development with a view to entrepreneurial, nationally and internationally competitive and socially relevant professional performances in the areas of Arts and Music Industries.
From ESML site (“about us”)
Great Hall
Also called Vianna da Motta Auditorium is located at Lisbon School of Music. This room was designed by the Portuguese architect Carrilho da Graça and by the Belge acoustician Daniel Commins. The stage possesses a flat wooden floor on joists, the audience area is tilted approximately 20º in relation to the horizontal plane and has two wooden flights of stairs in between the rows of chairs. The walls surrounding the audience go continuously around the stage in a roughly trapezoidal shape and consist entirely of large-scale shape-optimized reflection phase grating diffusors.
Small Hall
Located at Lisbon School of Music, this hall was designed by the Portuguese architect Carrilho da Graça. It has a seating capacity for 58 persons, with features that gives it versatility to host various cultural events, like music, conferences, theater, dance, and cinema.
Organ Room
Located at Lisbon School of Music, this room is specific for organ music practicing and rehearsal, it also holds periodic performances for small groups.
Lourinhã Mercy Church
The Lourinhã Misericórdia Church dates from 1626, and its construction date is inscribed on the tympanum at the entrance. The facade of the church has a pointed gable, and the door is surmounted by a triangular tympanum, where the date 1626 and the phrase: “Blessed are the merciful, for they shall obtain mercy” are inscribed. In the building where the church is located, there is a Manueline portal of great artistic value, which belonged to the Chapel of the Holy Spirit.
The Church is currently part of the Museum Space of the Santa Casa da Misericórdia da Lourinhã. This space, in the heart of the village, presents a collection of inestimable value, with works of sacred art, liturgical objects and extremely relevant historical information to understand the role of the Santa Casa da Misericórdia as an active part in the development of the village of Lourinhã, over the last 450 years.
Lux Frágil
Disco Room
A famous nightclub located in Lisbon that opened on the 29th of September 1998. Lux Frágil, besides being a bar and disco, has hosted concerts, performances, exhibitions, book presentations and recordings and was even on the set of many television programs.
National Palace of Mafra
The Royal Building of Mafra is a Cultural Site inscribed on the World Heritage List by UNESCO in 2019, integrating the Royal Palace, the Basilica, a Convent, the Jardim do Cerco and a vast enclosure.
With more than 1200 classified hectares, this is the largest Portuguese national monument, of which more than 38000 m2 are related to the Convent Palace, ordered to be built by King D. João V.
UNESCO recognized this monument as a feat of architecture, engineering and the capacity of human genius. Based on projects by Filippo Juvarra, its final design was carried out by the German Johann Friedrich Ludwig and the construction was carried out by the chief engineer of the kingdom, Custódio Vieira. The first stone was laid on November 17, 1717, and the consecration of the Basilica took place on October 22, 1730.
Inside, one of the most important Enlightenment libraries in Europe stands out, with around 30,000 volumes. The Basilica’s bell towers hold one of the largest bell rings in the world, consisting of two carillons with a total of 98 bells; and inside this Royal Basilica, six historic organs, installed between 1792 and 1807, which returned to echo in the Basilica after its complete restoration in 2010. Not being the usual residence of the Royal Family, the Palace of Mafra has always been visited by kings, to attend religious festivals or hunt in the Tapada.
From https://palaciodemafra.pt
Basilica
The Basilica of the National Palace of Mafra is inspired by the great churches of Rome, it has one of the most significant collections of Italian sculpture of its time, with 58 statues, a large crucifix with archangels in adoration and three high reliefs, as well as an important set of painting, representative of some of the most famous painters active in Italy and France, in the early 1730s. The Basilica’s collection of vestments and liturgical implements is also very significant, due to its quality and rarity.
Also noteworthy is the bell ringing ensemble, with 120 bells, which comprise two of the largest carillons of the 18th century, cast in Antwerp and Liége in the workshops of Willem Witlockx and Nicolas Levache, respectively. The bells are associated with two clocks dating from the first half of the 18th century, as well as four automatons for automatic music.
Inside the Basilica there is a set of pipe organs, unique in the world, made up of six instruments designed to play together, built between 1792 and 1807 by Portuguese organ makers António Machado e Cerveira and Joaquim Peres Fontanes.
Library
The Library of the National Palace of Mafra is one of the most iconic spaces in the monument. It is one of the largest European libraries from the 18th century, in a single room, measuring 1000 m2. Here there are around 30,000 volumes that reflect the main themes of Enlightenment culture, more rational and scientific, predominating religious themes, but also medicine, pharmacy, history, geography, literature, philosophy, architecture and art, law, literature, etc.
The installation of the shelves took place in 1776 but only in 1791 were the books distributed on them. At the beginning of the 19th century, Frei João de Santa Ana completed the second inventory of books and organized them as they still exist today, with the northern part reserved for religious themes, and the southern part, for exact sciences and civil themes.
In addition to printed books, there is also an important collection of music books, incunabula (works printed between 1455 and 1500, such as the Nuremberg Chronicle, from 1493), and a collection of handwritten and illuminated books, such as the Books of Hours, from the 15th century. In its archive, there is a vast collection of musical scores by various composers: Marcos de Portugal, João de Souza Carvalho, José Joaquim dos Santos, João José Baldi, among others, many of them destined for the Basilica’s organs.
Confirming the importance of the Library, Pope Benedict XIV granted it a bull in 1754, authorizing the keeping of books prohibited by the Index, works considered subversive or for dealing with themes condemned by the Church and the State.
National Theatre D. Maria II
Garrett Hall
Is the main hall of the National Theatre D. Maria II in Lisbon. The Garrett Hall was designed by the Italian architect Fortunato Lodi in a classic horseshoe shape and opened at 13th April 1846. In 1964, the theatre was destroyed by a fire, which led to a full reconstruction of the building, inaugurated in 1978. The restoration project focused on providing the best possible acoustic conditions, aiming at a 1 second reverberation time. Nowadays this hall is still mainly used for theatre performances, thus maintaining its original purpose.
São Carlos National Theatre
Theatre inspired by the 17th century, in a neoclassical style and with some Italian influences, namely from the Teatro di San Carlo, in Naples (designed in 1737 by G. A. Medrano) and the Teatro dela Scalla in Milan (by Guiseppe Piermarini and built between 1776 – 78). Its facade, with great decorative sobriety, is especially inspired by the latter. Several artists participated in the interior decoration of São Carlos, including, for example, Cirilo Volkmar Machado (foyer ceiling and stage opening), the Italian Appiani (royal tribune) and Manuel da Costa (hall ceiling). Built as a court theatre – with all its characteristics in internal architecture and function – for the bourgeoisie, constituting the first public theatre, open to any and all paying citizens. Its rapid construction, in just 6 months, was due to the great impulse of the Intendant Pina Manique.
Designed by architect José da Costa e Silva, the São Carlos National Theatre was built between 1792 and 1793 and opened on June 30, 1793, with a program consisting of the opera “La Ballerina Amante”, by Domenico Cimarosa, followed by the ballet “A felicidade lusitana” , by Caetano Gioia and a sung eulogy was included, composed by António Leal Moreira, as part of the celebrations of the pregnancy of Princess Carlota Joaquina, to whom the Teatro de São Carlos was dedicated.
A National Monument since 1996, the São Carlos National Theatre is one of the oldest theatres in Europe and the only opera theatre in Portugal.
Located in the historic centre of Lisbon, in Chiado, it is located among 19th century buildings and has other classified properties nearby. The São Carlos National Theatre is made up of an architectural complex made up of three properties: the main body of the Theatre, built between 1792 and 1793 and classified as a National Monument, the Duques de Bragança annex incorporated in 1888 and a third called the Serpa Pinto annex, incorporated in 1933. The longitudinal section of the Theatre clearly identifies the three articulated volumes and a differentiated roof. Inside, spaces are considered such as: foyer, grand hall, main opera room, with an elliptical plan with five orders of boxes, Italian type, stage box, technical areas, dressing rooms, rehearsal rooms and administrative rooms.
Main Opera Hall
The Main Hall of the São Carlos National Theatre is designed for Opera. By placing reflectors in the shape of an acoustic shell, the hall also offers excellent acoustic conditions for classical music concerts.
Great Hall
The Great Hall of São Carlos National Theatre is on the 4th level of boxes of the Main Opera Hall and features rich internal decoration in the style of the end of the 18th century. It hosts recitals and concerts with different instrumental formations, opera readings and more intimate performances.
St. Dominic Convent
Church
Inaugurated on the 21st of March 1994 by the Dominican Order as the first male catholic convent built in Lisbon since the last 250 years. Designed by Portuguese architects José Fernando Gonçalves and João Paulo Providência, it is a modern church of sober and minimalist lines, with a rectangular shaped floor and a considerable large height. The space has a large window that opens onto the inner cloister, the floor is slightly inclined towards the altar and its interior decoration is also very minimalistic, without figures or images.
St. George Cinema
Manoel de Oliveira Room
The main hall of this cinema in Lisbon is called Manoel de Oliveira (after the famous Portuguese filmmaker). The cinema opened in 1950 and was remodeled several times, the last refurbishment took place in 2001. It is a hall with a seating capacity for 830 persons divided into 3 audience stalls.
São Vicente de Fora Monastery
The Monastery of St. Vincent de Fora was built by order of D. Afonso Henriques in 1147, following a promise during the siege of Lisbon: if he managed to conquer the city of Lisbon from the Moors, he would order the construction of the monastery dedicated to St. Vincent, a highly venerated saint among the Mozarabs. This monastery was founded in the same year, on the “outside” side of the city walls, the building’s toponymy being thus justified.
Over the centuries, different Portuguese kings left their mark on the monastery, notably through the imposing 16th century reconstruction ordered by king D. Filipe I of Portugal (II of Spain), making the building one of the pioneering examples of Mannerism in Portugal. Also noteworthy is the rich decorative artistic filling applied during the sumptuous reigns of D. Pedro II and D. João V.
On a visit to the Monastery, with one of the best panoramic views of the Tagus River and the city of Lisbon, one can appreciate some renowned paintings ranging from the 17th century until the end of the 18th century, as well as one of the largest collections of baroque tiles in situ in the world, with more than 100 thousand tiles, which includes a unique exhibition of 38 fables by la Fontaine. The Monastery also contains the royal pantheon of the last dynasty of Portuguese kings (Bragança Dynasty), an imposing church with a canopy and historic organ from the Baroque period, rooms covered with inlaid marble, among other varied exhibitions and spaces.
Church
The Church of the Monastery of São Vicente de Fora has a sober and symmetrical façade in the Italian style, with a tower on each side and statues of Saints Vincent, Augustine and Sebastian above the entrance. The façade contains two turrets that rise on showy columns, open with windows and adorned with parapets. Two domes emerge from between them. A parapet of thirty-three meters, adorned with ornaments, joins the two turrets above the central body. The church has a longitudinal plan composed of a Latin cross, with a single nave with 6 interconnecting side chapels, an inscribed transept and a chancel with a rear choir. Inside the Church, a set of works ordered by King D. João V stands out:
- a baroque style canopy by Machado de Castro, supported by four powerful columns above the imposing altar, by Johann Friedrich Ludwig, flanked by eight life-size white painted wooden statues; on high plinths stand out the eight monumental images in the Italian style of the Mafra Ludoviciana School, two representing St. Vincent and St. Sebastian, made by Manuel Vieira, who is also responsible for the beautiful sculptures of angels, placed over the access doors to the canons’ choir;
- a historic organ built in 1765 by the organ maker João Fontanes de Maqueira, constituting one of the best and largest examples of Portuguese organ work from the 18th century;
- a transept, wide and with admirable architectural sense, limited around it by an order of six pilasters, identical to those of the nave. On it rested the large dome, which collapsed in the 1755 earthquake. Currently, a rotunda skylight, made of wood, torn by eight rectangular windows, somewhat disguises this absence.
Cloister
The former Augustinian Monastery adjacent to the Church, accessed through its nave, preserves its 16th century cistern and traces of the old cloister. It also stands out for its 18th century tile panels: at the entrance, next to the first Cloister, scenes from D. Afonso Henriques’ attacks on Lisbon and Santarém by Manuel dos Santos are depicted. Around the two cloisters, tile panels with rural scenes, surrounded by floral designs and cherubs, illustrate La Fontaine’s fables.
Technical Details
Acquisition Equipment
The acquisition procedure in terms of the used hardware and software has thus become now more or less stable. The following equipment has been used:
Source:
Lookline DL-303 omni dodecahedron loudspeaker.
Microphones:
2 Earthworks M30 omnidirectional measuring microphones,
1 Binaural Enthusiast B1-E dummy head with BE-P1 microphones,
1 Sennheiser Ambeo VR microphone,
1 Zylia ZM-1-3E 3rd order Ambisonics microphone.
Audio Interfaces:
Steinberg UR44, ESI U108PRE.
Software:
Custom scripts and functions in GNU Octave 6.4.0 using double precision FP arithmetic, developed in the last years by the authors
Acquisition Procedure
The dodecahedron loudspeaker was used for radiating exponential sine sweeps, or synchronized exponential sine sweeps, generated in the Octave software.
The sweeps recorded with the microphone array were registered synchronously through the ASIO compatible audio interface with the Octave software that calculated the corresponding impulse responses: stereo, binaural and 1st order A format Ambisonics (when using the Sennheiser Ambeo VR mic). The sweeps recorded by the Zylia mic were registered with its proprietary software (Zylia Studio) on 19 channel A format Ambisonics wave files and the corresponding impulse responses were also calculated in Octave.
The impulse responses were obtained by deconvolving the recorded sweeps with the inverse signal of the used exponential sine sweep, generated in the Octave software. When synchronized exponential sine sweeps were used, then the deconvolution was done analytically in the frequency domain employing the Fourier Transform of the synchronized swept-sine signal.
The sweeps recorded through stereo, binaural and 1st order Ambisonics mics were digitized with a sampling rate of 96 kHz, except for the two older acquisitions (ESML Great and Small Hall) where a rate of 44.1 kHz was used; a quantization depth of 32 bits FP was used in all cases. For the sweeps recorded with the 3rd order Ambisonics mic a sampling rate of 48 kHz with a quantization depth of 32 bits FP was employed.
RIR Processing
The raw audio as recorded in situ containing the RIRs was post-processed for the purpose of denoising and for converting the Ambisonics A-format responses into convenient B-format responses. Denoising is necessary due to the inherent background noise that is present in the spaces and, to a lesser extent, also in the acquisition chain, that limits the achievable signal-to-noise ratio (SNR). The achieved SNRs (of the order 80 – 90 dB, broad-band) are more than enough for characterization of the spaces using ISO 3382-1 standard room acoustical parameters, but the noise present in the RIRs can still be audible when using them for reverb convolution. The adopted solution consists in truncating all responses before the decay reaches the level of the background noise. The procedure employed for this truncation is based on the so-called Lundeby algorithm, which gives very good results in most cases.
After denoising, the associated main acoustical parameters specified in the ISO 3382-1 standard were calculated for each RIR and stored in text files. The calculated parameters set include signal-to-noise values, reverberation times (EDT, T10, T20, T30, T60), clarity indexes (D50, C50, C80), center times and IACC values in the case of binaural responses.
The conversion of A-format to B-format was carried out in Reaper using the proprietary plug-ins from Sennheiser (Ambeo A-B Format Converter, v1.2.0) and from Zylia (Ambisonics Converter v1.7.0).
Space’s RIR Details
REVERBDATA Articles
- D. Alarcão, A. Couto Pinto – ” The REVERBDATA Room impulse response database“, AES Europe 2024, Madrid, Spain, 15 – 17 June 2024 (https://aes2.org/publications/elibrary-page/?id=22551)
- D. Alarcão, A. Couto Pinto, G. Marramaque, F. Mendonça – ” REVERBDATA – a RIR database of Portuguese architectonic spaces“, TECNIACÚSTICA 2024, Faro, Portugal, 11 – 13 September 2024 (PDF File)
Contacts
Prof. Dr. Diogo Alarcão
CESEM – Centre for the Study of the Sociology and Aesthetics of Music
ESML – Music Technologies, Lisbon School of Music
IPL – Polytechnic University of Lisbon, Portugal
email: dalarcao@esml.ipl.pt
Prof. Dr. António Couto Pinto
CEDET – Center for Studies and Development of Electronics and Telecommunications
ISEL – Lisbon Engineering Institute
ESML – Music Technologies, Lisbon School of Music
IPL – Polytechnic University of Lisbon, Portugal
email: apinto@esml.ipl.pt
Português