# Courtyard Sound Field Characteristics by Bell Sounds in Han Chinese Buddhist Temples
## 4 Conclusions  
This study established and analysed a standard Han Chinese Buddhist temple courtyard sound field model, which yielded the following results. (1) An increase in temple courtyard wall height will increase sound reflection in courtyards, which will, in turn, significantly increase the SPL(A) of each courtyard and make the sound fields more uniform. As shown by the temple model that was established in this study, for every wall height increase of 1.5 m, the SPL(A) of the second through fourth courtyards increased by 0.7 to 2.3 dBA. An increased wall height will increase RT and decrease C\({}_{80}\), to some extent. When wall height exceeds the height of the sound source, the courtyard's sound field will no longer be varied. (2) Traditional temples usually do not have partition walls between courtyards. The simulation model showed that adding partition walls between courtyards did not have significant effects on the SPL(A) of the first and second courtyards, but it decreased the SPL(A) and (1-IACC\({}_{\rm E3}\)) of the third and fourth courtyards, which were relatively far from the sound source. Adding courtyard partition walls also increased the EDT\({}_{\rm m}\) of the second through fourth courtyards by 52%, 42%, and 21%, respectively, but decreased their C\({}_{80}\). (3) The position of the bell tower affected nearby courtyards' SPL(A). The model showed that there were no significant differences between the Qing and Song dynasties' bell tower layouts regarding the SPL(A) and C\({}_{80}\) of the second through fourth courtyards. However, these two layouts led to  
Figure 12: Diagrams of the effects of flooring materials on courtyard sound fields. (**a**) Variation in SPL(A). (**b**) Variation in EDT\({}_{\rm m}\). (**c**) Variation in C\({}_{80}\). higher SPL(A) and C\({}_{80}\) than a third layout in which the bell tower was located at the centre of the first courtyard. The (1-IACC\({}_{\text{E3}}\)) of each courtyard was greater with the Qing dynasty layout than with the Song dynasty layout. Furthermore, the Qing dynasty layout reduced the sound field uniformity of the second through fourth courtyards. Changes in bell tower height also significantly affect a temple's interior and exterior sound fields. When the sound source was 3 m above the ground (i.e., the same height as the wall), both T\({}_{\text{30m}}\) and EDT\({}_{\text{m}}\) reached their maximum values in each courtyard; when the sound source was 6 m above the ground, C\({}_{80}\) reached its maximum values. (4) With regard to courtyard materials, changes in a courtyard wall's sound absorption coefficient led to significant sound field changes. The simulation showed that for every increase of 0.3 in the sound absorption coefficient, the SPL(A) of the second and third courtyards decreased by 1.2 to 4.0 dBA, and the fourth courtyard's SPL(A) decreased by 2.2 to 4.6 dBA, causing non-uniform distribution of courtyard SPL(A) and decreasing the EDT\({}_{\text{m}}\) and T\({}_{\text{30m}}\) of each courtyard, while increasing C\({}_{80}\), to some extent. However, changes in materials, such as those used in roofs and in windows, did not significantly affect Buddhist temples' courtyard sound fields. In short, with a bell as the sound source, spatial elements that have significant effects on Buddhist temples' courtyard sound fields include the following: (a) courtyard wall height, (b) position of courtyard partition wall, (c) position and height of bell tower, and (d) the courtyard wall's sound absorption coefficient. Our research indicates that the temple layout of the [PERSON] dynasty (that is, the bell tower with a height of 6 m located in the first courtyard; the brick courtyard walls with a height of 3 m; and the absence of partition walls between most courtyards), which is adopted by most traditional temples, is beneficial to the spread of the bell sound inside and outside the Chinese Buddhist Temple; therefore, this layout style could be applied to newly built temples.