Antonio Pedro O. Carvalho
Acoust. Lab., Dept. Civil Eng., Faculty of Eng., Univ. of Porto, R. Bragas, P-4099 Porto Codex, Portugal
Reverberation time (RT) measurements were taken at several source/receiver
locations in 41 Catholic churches in Portugal built in the last 14 centuries,
using the impulse--response method. The use of the Sabine and Eyring
reverberation time equations was tested to estimate the measured RTs in this
sample of churches. The effect of coupled spaces was analyzed, and a new
algorithm for the application of the Sabine equation in churches was developed
producing an average of 16% in the differences between the predicted and
measured RTs compared to 71% using the standard Sabine equation. Coupled spaces
were found to act as windows with a characteristic absorption coefficient
depending on their dimensions. The recesses in churches were grouped in three
types: main altar area, chapels, and lateral aisles, each having a particular
acoustical behavior. It was found that those recesses only acted as coupled
spaces if their length/opening