Sara Girón

Acoustic analysis in Mudejar-Gothic churches: Experimental results

This paper describes the preliminary results of research work in acoustics, conducted in a set of 12 Mudejar-Gothic churches in the city of Seville in the south of Spain. Despite common architectural style, the churches feature individual characteristics and have volumes ranging from 3947 to 10 708 m3. Acoustic parameters were measured in unoccupied churches according to the ISO-3382 standard. An extensive experimental study was carried out using impulse response analysis through a maximum length sequence measurement system in each church. It covered aspects such as reverberation (reverberation times, early decay times), distribution of sound levels (sound strength); early to late sound energy parameters derived from the impulse responses (center time, clarity for speech, clarity, definition, lateral energy fraction), and speech intelligibility (rapid speech transmission index), which all take both spectral and spatial distribution into account. Background noise was also measured to obtain the NR indices. The study describes the acoustic field inside each temple and establishes a discussion for each one of the acoustic descriptors mentioned by using the theoretical models available and the principles of architectural acoustics. Analysis of the quality of the spaces for music and speech is carried out according to the most widespread criteria for auditoria.

Acoustic energy relations in Mudejar-Gothic churches

Extensive objective energy-based parameters have been measured in 12 Mudejar-Gothic churches in the south of Spain. Measurements took place in unoccupied churches according to the ISO-3382 standard. Monoaural objective measures in the 125-4000 Hz frequency range and in their spatial distributions were obtained. Acoustic parameters: clarity C80, definition D50, sound strength G and center time Ts have been deduced using impulse response analysis through a maximum length sequence measurement system in each church. These parameters spectrally averaged according to the most extended criteria in auditoria in order to consider acoustic quality were studied as a function of source-receiver distance. The experimental results were compared with predictions given by classical and other existing theoretical models proposed for concert halls and churches. An analytical semi-empirical model based on the measured values of the C80 parameter is proposed in this work for these spaces. The good agreement between predicted values and experimental data for definition, sound strength, and center time in the churches analyzed shows that the model can be used for design predictions and other purposes with reasonable accuracy.

Acoustic simulations of Mudejar-Gothic churches.

In this paper, an iterative process is used in order to estimate the values of absorption coefficients of those materials of which little is known in the literature, so that an acoustic simulation can be carried out in Mudejar-Gothic churches. The estimation of the scattering coefficients, which is even less developed, is based on the size of the irregularities. This methodology implemented is applied to six Mudejar-Gothic churches of Seville (southern Spain). The simulated monophonic acoustic parameters, both in the frequency domain and as a function of source-receiver distance (spatial distribution), are analyzed and compared with the in situ measures. Good agreement has been found between these sets of values, whereby each parameter is discussed in terms of the just noticeable difference. This procedure for existing buildings, especially for those which are rich in heritage, enables a reliable evaluation of the effect on the maintenance, restoration, and conditioning for new uses, as well as the recreation of the acoustic environment of ancient times. Along these lines, the acoustic influence of the timber roof and the presence of the public in these churches have also been studied.

Clarity and Definition in Mudejar-Gothic Churches

This paper studies the C80 and D50 objective acoustic indices in relation to source-receiver distance for five different octave bands inside Mudejar-Gothic churches. This type of church, eight examples of which we have studied in the city of Seville, is characterised by good acoustic conditions as far as this can be indicated by reverberation times. This article aims to supply more data on these values and to explore the dependence of these measurements on receiver position. Finally, the experimental results have been compared with expected results derived from a semiempirical analytical model proposed.

Magneto-optic Kerr effect in amorphous FexSi1−x

Abstract The magneto-optic Kerr effect amplitude ΔR/R is measured in amorphous Fe x Si 1− x films for different incidence angles versus photon energy in the 1.2–5 eV range. As a general result and contrary to expectations, the effect amplitude is lowered upon crystallization without any important change of the spectral structure.

Correlations of the Acoustic Fields of Mudejar-Gothic Churches

This paper studies the statistical correlations between monaural acoustic parameters with themselves and with architectural parameters from an acoustical survey undertaken in 12 Mudejar-Gothic churches in Seville, southern Spain. Objective room-acoustic parameters have been measured using impulse response analysis through a maximum-length-sequence measurement system in each church. Measurements cover time parameters (reverberation time, early decay time); levels (sound strength); energy-based parameters (centre time, clarity for speech, clarity, definition, early lateral energy fraction); and speech intelligibility (rapid speech transmission index) and the analysis takes into account both spatially averaged values and individual positions. The aim of the study is to identify the main architectural factors that have relevant influence on the acoustic fields of the churches, and the minimum number of room acoustic parameters which are able to describe adequately this acoustic field, thus the possible excess of information is evaluated. Significant correlations have been found that, in the best cases, correspond to fits using pairs of independent variables instead of one single variable. The best option to describe the six subjective attributes of sound perception in these buildings consists of three acoustic parameters formed by two different pairs plus the early lateral energy fraction.

Experimental Study of Support Parameters on Auditorium and Proscenium Stages

This paper deals with measurements of early and late support parameters on the stages of 9 concert halls within the theatre heritage of Andalusia (southern Spain). The enclosures under investigation belong to two main categories of buildings: 7 proscenium theatres of two typologies (horseshoe-shaped and shoebox-shaped ground plans) and 2 auditoria. Wherever possible, measurements covered the two configurations with and without orchestra shells on the stages. The experimental procedure was carried out according to the ISO 3382-1 where monophonic impulse responses were measured using sine sweep signals in the 125-4000 Hz octave band range on the stage and in the audience area. The experimental results of support parameters versus frequency are compared with their predictions through the diffuse field theory using the reverberation times measured in the halls. The relationships of spectrally averaged support parameters with architectural elements of the enclosure of the stage are studied. Results show that the most significant regressions are for early support with the volume of the stage enclosure and its height/width ratio. The differences found in support measures due to the addition of the orchestra shells are also examined.

Subjective ranking of concert halls substantiated through orthogonal objective parameters

This paper studies the global subjective assessment, obtained from mean values of the results of surveys addressed to members of the audience of live concerts in Spanish auditoriums, through the mean values of the three orthogonal objective parameters (Tmid, IACCE3, and LEV), expressed in just noticeable differences (JNDs), regarding the best-valued hall. Results show that a linear combination of the relative variations of orthogonal parameters can largely explain the overall perceived quality of the sample. However, the mean values of certain orthogonal parameters are not representative, which shows that an alternative approach to the problem is necessary. Various possibilities are proposed.

Simulated acoustic field in mudejar‐gothic churches

The most significant acoustic parameters in a set of mudejar‐gothic churches were measured (all the churches were located in the city of Seville). From the analysis of these data important conclusions were otained about the behavior of the reverberant field versus source–receiver distance [J. Sendra et al., Computational Acoustics and its Environmental Applications—II (Computation on Mechanics Publications, Southampton, 1997), pp. 139–148] from Barron‘s revised theory [Barron et al., J. Acoust. Soc. Am. 84, 618–628 (1988)] and the relations between several acoustics quality descriptors: C80, D50, and RASTI [Zamarreno et al., Proceedings Acustica‐98, Lisbon (1998)]. The three most representative churches were chosen to carry out a computer simulation with the raynoise software. Absorption coefficient values used in the model have been adjusted using measured reverberation time data, and thus the results were obtained for the other acoustic parameters in the different octave bands. It was proven that, in ge...

Method for the Economic Profitability of Energy Rehabilitation Operations: Application to Residential Dwellings in Seville☆

Abstract This work proposes a method based on a computer model to assess the economic profitability of energy rehabilitation operations in the envelope of a block of residential dwellings (Virgen del Carmen) in Seville (Southern Spain). The work evaluates the influence that certain hypotheses of interventions in the opaque part of the envelope exert on the annual energy demand: better insulation of the facade, interior partitions, roof and ground floors, in addition to its semi-transparent part: improvements in the airtightness of the building openings, the glass windows, and the thermal conductivity of its frame. These interventions arise from strict compliance with the Spanish regulatory framework. This model has been designed for the context of a Mediterranean climate, (mild winters and hot summers). The simulation tool Design Builder 3.4.0.041, which uses the calculation engine Energy Plus 8.1, has been selected to generate the computing model and establish its energy demand. The amortization of the economic costs of rehabilitation is quantified by the net present value (NPV) index, in accordance with the savings in the bills of energy consumption due to the reductions in demand for heating and cooling in the building, thereby obtaining an amortization period which exceeds 22 years.