A comparative analysis of acoustic energy models for churches

Abstract

Different models to improve prediction of energy-based acoustic parameters in churches have been proposed by different researchers [E. Cirillo and F. Martellotta, J. Acoust. Soc. Am. 118, 232-248 (2005); T. Zamarreño et al., J. Acoust. Soc. Am. 121, 234-250 (2006)]. They all suggested variations to the "revised" theory proposed by Barron and Lee [J. Acoust. Soc. Am. 84, 618-628 (1988)], starting from experimental observations. The present paper compares these models and attempts to generalize their use taking advantage of the measurements carried out in 24 Italian churches differing in style, typology, and location. The whole sample of churches was divided into two groups. The first was used to fine-tune existing models, with particular reference to the "mu model," which was originally tested only on Mudejar-Gothic churches. Correlations between model parameters and major typological and architectural factors were found, leading to a classification that greatly simplifies parameter choice. Finally, the reliability of each model was verified on the rest of the sample, showing that acoustic parameters can be predicted with reasonable accuracy provided that one of the specifically modified theories is used. The results show that the model requiring more input parameters performs slightly better than the other which, conversely, is simpler to apply.

A Revised Sound Energy Theory Based on a New Formula for the Reverberation Radius in Rooms with Non-Diffuse Sound Field

“…Thus, they proposed a model based on the following assumptions: the direct sound is followed by linear level decay at a rate corresponding to the reverberation time; the instantaneous level of the late decaying sound is uniform throughout the space; the time t 0 corresponds to the time the signal is emitted from the source, therefore the direct sound reaches a point at a distance r from the source after a time t D = r/c. In this way the integrated energy decreases when the source-receiver distance increases, while the early/late reflected energy ratio remains constant; the integrated value for the reflected sound level is assumed to be, at r = 0, equal to the value predicted by the classic theory (Berardi et al, 2009). According to the Barron and Lee's revised theory of sound decay, the sound energy may be calculated as G = 10 log 10 (100/r 2 + 31200 · T /V · e (−0.04·r/T ) ).…”

“…Although applying the revised theory to concert halls markedly improves the prediction accuracy compared to classic theory, the revised theory still has some limitations (Vorländer, 1995;Berardi et al, 2009). In particular, there has been significant discussion in the last years about the appropriate starting time t 0 for the integration of the reverberant field.…”

The influence of the distribution of sound absorbing materials on the estimation of reverberation time in rooms

“…Reverberation time plays a significant role in the design of school rooms [1], sacral rooms [2][3][4], auditoriums [5], theaters and concert halls [6], open-plan spaces [7], or others. This parameter has been investigated in many different works, a few of them mentioned below in the last years [8][9][10].…”

A Double Synthetic Index to Evaluate the Acoustics of Churches

“…The values of C 50 above −6 dB were considered optimal for the clarity. The previous value, which may seem low for architectural acoustics, is common in many churches (Kosala, Engel, 2005;Cirillo, Martellotta, 2006) and is partially related to the high reverberation and late reflections in churches (Berardi et al, 2009a).…”

“…However, in this paper, the attention is focused on worship spaces. In fact, an increasing number of studies have been focused on the acoustics of churches, whose peculiarities are different from those of concert halls and theatres (Berardi et al, 2009a). Large surveys have contributed to create a consistent body of knowledge about the acoustics of churches in Portugal (Carvalho, 1994), Spain (Sendra et al, 1999), Poland (Kosala, Engel, 2005), Italy (Cirillo, Martellotta, 2006), and Japan (Soeta et al, 2012).…”