INTERNATIONAL CONGRESS ON ACOUSTICS MADRID , 2-7 SEPTEMBER 2007 ACOUSTICAL ASPECTS OF THE SAGRADA FAMILIA CHURCH PACS

It is said that Antoni Gaudi (1852-1926) envisaged the Sagrada Familia as a gigantic musical instrument. Each pinnacle seems to be designed as a belfry, in which many tubular bells will be installed. Its upper section of the Nativity Façade has numerous windows with characteristic louvers. The lower section is almost closed and connected to the nave through muffler-like structures. Therefore, Gaudi’s bell music is to be radiated exterior as well as to be propagated interior to the nave. Acoustic radiation from the windows and propagation through lower structures are simulated by two-dimensional FDTD (Finite Difference in Time Domain) method. The window yields a broad directivity pattern in lower frequencies (63 Hz – 500 Hz) and a beam pattern formed by a kind of line array consisting of secondary sources in higher frequencies (500 Hz – 2 kHz). Six receiving points along the lower structure indicate interactions between the direct sound from the top of the lower section and the reflection from the floor. Also, an impulse-response measurement on a 1/25-scaled model of the lower structure suggests that an attenuation of 40 dB is estimated above 100 Hz and that the frequencies below 110 Hz are strongly cut off. INTRODUCTION The construction of the Sagrada Familia Church began in 1882. Gaudi was commissioned with the direction of the work in 1883 shortly after the resignation of the architect Francesc de P. Villar. However, Gaudi died by traffic accident in 1926 at the first stage of the huge Sagrada Familia Project. In 1936 the Civil War destroyed the Gaidi’s studio and workshop, from which Gaudi’s original materials were lost. Nevertheless, the construction is still going on. The support to this construction should be considered from various directions. It is important for the future continuators to create new ideas and incorporate them into the construction. In addition, it is needed to look for Gaudi’s original intention based on the surviving things and matters. According to the ground plan of the Sagrada Familia [1, 2], three facades (the Nativity, the Passion, and the Glory Façade) are constructed facing to the east, west, and south, respectively. Each Façade consists of the four bell towers. The height of the longest tower exceeds 100 meters. The Nativity Façade was almost completed by Gaudi himself, and the Passion Façade was completed by the next-generation architects. The Glory façade has not been completed yet. The altar faces the north. Furthermore, six main towers will rise over the central nave, which is surrounded by the side aisles. The 12 towers rising from the three facades are the belfries. It is said that Gaudi planed to install many bells and transmit bell music to the city of Barcelona. In fact, Gaudi carried out the propagation experiment using a model bell in 1914. Also, it is designed to lead this bell music to the central nave in the Sagrada familia. BASIC STRUCTURE OF THE NATIVITY FAÇADE The Façade of Nativity, which was constructed by Gaudi, is divided into two both horizontally and vertically. Figure 1 depicts the cross-sectional view. The Façade is vertically divided at the central surface passing through the choir loft. That is, the Façade has twin-tower structure. We thus consider the left half. Also, the Façade may be horizontally divided into the upper structure (the bell tower with many windows) and the lower structure (the lower section of the bell tower