Courtyard Sound Field Characteristics by Bell Sounds in Han Chinese Buddhist Temples

Round 1

Reviewer 1 Report

Since this study considered only bell tower as a sound source, the title should be limited to emphasize its research range like "sound field characteristics by bell sounds". Also, sound power level of the actual bell sound should be employed to the simulation. If the authors consider more sound sources, for example, monk chanting or people talking in courtyard, etc., then, the simulation results with various spatial elements might be discussed more meaningfully. In consideration of bell sound characteristics, is it meaningful to investigate speech intelligibility or musical clarity parameters? As shown in Fig. 5 and Table 1, it seems that the simulated results showed larger differences to the measured results in regard to JND values. Are there any elements to improve the simulation medels? The target venue is confusing. A standard model was selected as shown in Fig. 2 , and, the same model was investigated as shown in chapter 3. Then, three models as shown in Fig. 3 are employed only for acoustical fitting and measurement? If so, this part can be deleted since it has no direct relationship with the target venue. Acoustical fitting with measurement date should be the best, but if not, adopting settings from the references might be acceptable. In conclusion part, further application with the findings from this study should be more described.

Author Response

Response letter

Manuscript ID: applsci-700320

Title: Courtyard sound field characteristics by bell sounds in Han Chinese Buddhist temples

(The effects of Han Chinese Buddhist temples’ layouts and spatial elements on courtyard sound fields)

Author: Dongxu Zhang*, Chunxiao Kong, Mei Zhang and Qi Meng*

 

Dear Editor and Reviewers:

We appreciate the reviewers for the very helpful comments on our manuscript. We have studied comments carefully and have made correction which we hope meet with approval. Please see our point-by-point responses below. Our responses are in red.

 

Response to Reviewer 1 Comments

Point 1: Since this study considered only bell tower as a sound source, the title should be limited to emphasize its research range like "sound field characteristics by bell sounds".

Response 1: The title has been replaced by “Courtyard sound field characteristics by bell sounds in Han Chinese Buddhist temples”.

Point 2: Also, sound power level of the actual bell sound should be employed to the simulation.

Response 2: Thank you for the suggestion. The original paper did not express this aspect clearly. The sound source in the simulation employed the measured sound pressure level (SPL) value of bell sound. Considering that the sound power level of the temple bell sound is a variable value, the authors used the maximum value of measured SPL in the simulation process instead of the sound power value of the bell sound. Now according to the reviewer’s suggestion, the authors have added the explanation in the modified version as follows:

“Considering that the sound power level of the temple bell sound was a variable value, and only relative values from courtyard sound field simulation results were to be compared and analysed in this study, this set of SPL values was used to simulate a bell sound source instead of actual sound power level values.”(Please see 2.2)

Point 3: If the authors consider more sound sources, for example, monk chanting or people talking in courtyard, etc., then, the simulation results with various spatial elements might be discussed more meaningfully.

Response 3: Thanks for the suggestion. Bell sound is the most representative sound source in courtyards in Chinese Buddhist temples. The title of the revised paper has been changed and limited to bell sounds, thus, other sound sources were not considered. Monk chanting or people talking in courtyards are also common in temples, but these sound pressure levels are too low and lack influence in courtyards. One explanation was added in the revised manuscript as follows:

“In this study, the Chinese Buddhist temple’s ringing bell, their most representative sound source, was selected. Other sound sources were not considered because these sounds were uncommon in the courtyard or had sound pressure levels that were too low.” (Please see 2. 2)

Point 4: In consideration of bell sound characteristics, is it meaningful to investigate speech intelligibility or musical clarity parameters?

Response 4: This is a good suggestion, in the revised paper the STI parameters (speech intelligibility) has been removed. Meanwhile, the authors considered that the bell could also be understood as a kind of music, so the C₈₀ parameters (musical clarity) in the paper have been retained.

Point 5: As shown in Fig. 5 and Table 1, it seems that the simulated results showed larger differences to the measured results in regard to JND values. Are there any elements to improve the simulation models?

Response 5: In the process of this study, numerous computer simulations were performed after field measurement, and the parameters used in the current study were the nearest simulated values to the measured results. One explanation about research limitation was added in the revised manuscript as follows:

“The simulation accuracy of this study had not entirely met the common acoustic criteria in interior space, which requires that the simulated error of RT should be less than its JND [41]. However, we consider the errors in this study to be within an acceptable range based on the following reasons: 1) There was a lack of related research about standard acoustic parameters of materials in ancient Chinese architecture. The sound absorption coefficients of ancient materials used in our simulation research were from those of relevant building materials in acoustic reference books, which may be different from the actual sound absorption coefficients of the site’s materials. 2) The measurements were conducted in outdoor spaces; the courtyard scale was large; reverberation resulted from multiple reflections; and the acoustic model simplified the building and the courtyard in the simulation process. These factors would affect the measurements and simulation accuracy in this study. 3) Relative values from courtyard sound field simulation results were compared and analysed, and the results of middle frequency (the bands of 500 Hz and 1000 Hz, which also is the main frequency range of human language), wherein errors were relatively small, were chosen as representative data. 4) The purpose of this study is not to obtain acoustic results for engineering calculations but to analyse characteristics of the courtyard sound field in Chinese Buddhist temples by means of comparing changing trends of the sound field.”(Please see 2. 3)

Point 6: The target venue is confusing. A standard model was selected as shown in Fig. 2 , and, the same model was investigated as shown in chapter 3. Then, three models as shown in Fig. 3 are employed only for acoustical fitting and measurement? If so, this part can be deleted since it has no direct relationship with the target venue. Acoustical fitting with measurement date should be the best, but if not, adopting settings from the references might be acceptable.

Response 6: Thanks for the suggestion. The original paper did not express this aspect clearly. Some explanations were added in the revised manuscript as follows:

“First, there is a lack of references for the simulation of a courtyard sound field in Han Chinese Buddhist temple for this paper. Moreover, it is prohibited to fully and systematically measure the sound field in a Buddhist temple as it is a sacred religious space in China. Therefore, in order to ensure the accuracy of the simulated temple sound fields in this research, courtyard sound field measurements were taken at Shenyang Imperial Palace, which has a similar architectural form to traditional Buddhist temples and uses comparable materials; notably, however, there are no Buddhist bell towers and drum towers in the courtyard of Shenyang Imperial Palace. Next, the sound absorption and scattering coefficients of traditional Chinese building materials were determined in the sound field simulation software by comparing simulated and measured data. Those coefficients will be used in the following simulation of Buddhist courtyard sound field.” (Please see 2. 3)

“Three courtyards in Shenyang Imperial Palace were selected and their sound fields were measured and simulated; further, results were cross-verified to ensure the accuracy and universality of the simulation.” (Please see 2. 3)

Point 7: In conclusion part, further application with the findings from this study should be more described. 

Response 7: According to this suggestion. One explanation was added in the revised manuscript as follows:

“Our research indicates that the temple layout of the Qing 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.” （please see 4. Conclusion）

 

Response to Reviewer 2 Comments

This is an interesting paper, overall well-organized.

Point 1: I think the literature review could be slightly expand to focus more on the acoustics of worships spaces (also from other religions) and discuss how this compares with the case of Han Chinese Temples as presented here.

Response 1: Thanks for the suggestion. Some references and the discussion were added in the revised manuscript as follows:

1)“Soeta et al. found that in Japanese churches, changes in the direction could improve the intelligibility of speech. By contrast, source location had relatively little effect on acoustic parameter values. ³³” (Please see Introdution)

2)“Girón et al. summarised principal contributions to the acoustics of ancient occidental Christian churches in recent decades. ³⁴” (Please see Introdution)

3) “Manohare et al. analysed sound field characteristics of a large hollow stupa in an Indian Buddhist temple in Nagpur by means of an in situ measurement and simulation, and investigated the effects of these characteristics on religious activities. ³⁵” (Please see Introdution)

4) “Orfali and Ahnert discussed the current used sound systems in mosques, and introduced the effect of these systems on the mosques’ applicable sound parameter. ³⁶” (Please see Introdution)

5) “These different religions adopted different worship rituals and architectural space; however, all these studies have shown that the appropriate sound field was important for creating a religious atmosphere, and have provided useful reference for our study.” (Please see Introdution)

Reference：

Soeta, Y.; Ito, K.; Shimokura, R.; Sato, S.I.; Ohsawa, T.; Ando, Y. Effects of sound source location and direction on acoustic parameters in Japanese churches. Acoust. Soc. Am. 2012, 131, 1206. Girón, S.; Alvarez-Morales, L.; Zamarreno, T. Church acoustics: A state-of-the-art review after several decades of research. Sound. Vib. 2017, 411 378-408. Manohare, M.; Dongre, A.; Wahurwagh, A. Acoustic characterization of the Buddhist temple of Deekshabhoomi in Nagpur, India. Acoust. 2017, 24(3), 193-215. Orfali, W.; Ahnert, W. Evaluation of existing sound system designs in mosques and alternative modern solutions. Acoust. Soc. Am. 2008, 123(5), 3613.

Point 2: I think more limitations of current methodology should be discussed, such us the ODEON software (typically meant for indoor spaces): what kind of means did the authors implement to contain simulation uncertainty?

Response 2: Thanks for the suggestion. The discussion of current methodology was added in the revised manuscript as follows:

 “Considering that Odeon software is typically used to simulate the sound field of indoor spaces in most cases, the sound field model of a semi-closed courtyard in a Chinese Buddhist temple in this study was placed in a cube larger than the courtyard (Figure. 2); subsequently, sound absorption coefficients of this cube’s surfaces at each frequency were set to 1 (the sound was completely absorbed). With this setting, the sound field of a semi-closed courtyard could be more accurately simulated.” (Please see 2. 2)

Point 3: Also limitations of ISO 3382 should be taken into account as "performance spaces" are typically meant as (enclosed) concert halls.

Response 3: In response to the reviewers' suggestion, one explanation was added in the revised manuscript as follows:

(Note that ISO 3382 is usually used for enclosed performance spaces such as concert halls. The courtyards in Chinese Buddhist temples in this paper are semi-closed spaces, and some have certain performance functions. However, because of the lack of measurement specifications for these kinds of semi-closed spaces, this study refers to some measurement methods and parameters of ISO 3382). (Please see 2. 3)

 

 

Author Response File: Author Response.docx

Reviewer 2 Report

This is an interesting paper, overall well-organized.

I think the literature review could be slightly expand to focus more on the acoustics of worships spaces (also from other religions) and discuss how this compares with the case of Han Chinese Temples as presented here.

I think more limitations of current methodology should be discussed, such us the ODEON software (typically meant for indoor spaces): what kind of means did the authors implement to contain simulation uncertainty?

Also limitations of ISO 3382 should be taken into account as "performance spaces" are typically meant as (enclosed) concert halls.

Author Response

Response letter

Manuscript ID: applsci-700320

Title: Courtyard sound field characteristics by bell sounds in Han Chinese Buddhist temples

(The effects of Han Chinese Buddhist temples’ layouts and spatial elements on courtyard sound fields)

Author: Dongxu Zhang*, Chunxiao Kong, Mei Zhang and Qi Meng*

 

Dear Editor and Reviewers:

We appreciate the reviewers for the very helpful comments on our manuscript. We have studied comments carefully and have made correction which we hope meet with approval. Please see our point-by-point responses below. Our responses are in red.

 

Response to Reviewer 2 Comments

This is an interesting paper, overall well-organized.

Point 1: I think the literature review could be slightly expand to focus more on the acoustics of worships spaces (also from other religions) and discuss how this compares with the case of Han Chinese Temples as presented here.

Response 1: Thanks for the suggestion. Some references and the discussion were added in the revised manuscript as follows:

1)“Soeta et al. found that in Japanese churches, changes in the direction could improve the intelligibility of speech. By contrast, source location had relatively little effect on acoustic parameter values. ³³” (Please see Introdution)

2)“Girón et al. summarised principal contributions to the acoustics of ancient occidental Christian churches in recent decades. ³⁴” (Please see Introdution)

3) “Manohare et al. analysed sound field characteristics of a large hollow stupa in an Indian Buddhist temple in Nagpur by means of an in situ measurement and simulation, and investigated the effects of these characteristics on religious activities. ³⁵” (Please see Introdution)

4) “Orfali and Ahnert discussed the current used sound systems in mosques, and introduced the effect of these systems on the mosques’ applicable sound parameter. ³⁶” (Please see Introdution)

5) “These different religions adopted different worship rituals and architectural space; however, all these studies have shown that the appropriate sound field was important for creating a religious atmosphere, and have provided useful reference for our study.” (Please see Introdution)

Reference：

Soeta, Y.; Ito, K.; Shimokura, R.; Sato, S.I.; Ohsawa, T.; Ando, Y. Effects of sound source location and direction on acoustic parameters in Japanese churches. Acoust. Soc. Am. 2012, 131, 1206. Girón, S.; Alvarez-Morales, L.; Zamarreno, T. Church acoustics: A state-of-the-art review after several decades of research. Sound. Vib. 2017, 411 378-408. Manohare, M.; Dongre, A.; Wahurwagh, A. Acoustic characterization of the Buddhist temple of Deekshabhoomi in Nagpur, India. Acoust. 2017, 24(3), 193-215. Orfali, W.; Ahnert, W. Evaluation of existing sound system designs in mosques and alternative modern solutions. Acoust. Soc. Am. 2008, 123(5), 3613.

Point 2: I think more limitations of current methodology should be discussed, such us the ODEON software (typically meant for indoor spaces): what kind of means did the authors implement to contain simulation uncertainty?

Response 2: Thanks for the suggestion. The discussion of current methodology was added in the revised manuscript as follows:

 “Considering that Odeon software is typically used to simulate the sound field of indoor spaces in most cases, the sound field model of a semi-closed courtyard in a Chinese Buddhist temple in this study was placed in a cube larger than the courtyard (Figure. 2); subsequently, sound absorption coefficients of this cube’s surfaces at each frequency were set to 1 (the sound was completely absorbed). With this setting, the sound field of a semi-closed courtyard could be more accurately simulated.” (Please see 2. 2)

Point 3: Also limitations of ISO 3382 should be taken into account as "performance spaces" are typically meant as (enclosed) concert halls.

Response 3: In response to the reviewers' suggestion, one explanation was added in the revised manuscript as follows:

(Note that ISO 3382 is usually used for enclosed performance spaces such as concert halls. The courtyards in Chinese Buddhist temples in this paper are semi-closed spaces, and some have certain performance functions. However, because of the lack of measurement specifications for these kinds of semi-closed spaces, this study refers to some measurement methods and parameters of ISO 3382). (Please see 2. 3)

 

Response to Reviewer 1 Comments

Point 1: Since this study considered only bell tower as a sound source, the title should be limited to emphasize its research range like "sound field characteristics by bell sounds".

Response 1: The title has been replaced by “Courtyard sound field characteristics by bell sounds in Han Chinese Buddhist temples”.

Point 2: Also, sound power level of the actual bell sound should be employed to the simulation.

Response 2: Thank you for the suggestion. The original paper did not express this aspect clearly. The sound source in the simulation employed the measured sound pressure level (SPL) value of bell sound. Considering that the sound power level of the temple bell sound is a variable value, the authors used the maximum value of measured SPL in the simulation process instead of the sound power value of the bell sound. Now according to the reviewer’s suggestion, the authors have added the explanation in the modified version as follows:

“Considering that the sound power level of the temple bell sound was a variable value, and only relative values from courtyard sound field simulation results were to be compared and analysed in this study, this set of SPL values was used to simulate a bell sound source instead of actual sound power level values.”(Please see 2.2)

Point 3: If the authors consider more sound sources, for example, monk chanting or people talking in courtyard, etc., then, the simulation results with various spatial elements might be discussed more meaningfully.

Response 3: Thanks for the suggestion. Bell sound is the most representative sound source in courtyards in Chinese Buddhist temples. The title of the revised paper has been changed and limited to bell sounds, thus, other sound sources were not considered. Monk chanting or people talking in courtyards are also common in temples, but these sound pressure levels are too low and lack influence in courtyards. One explanation was added in the revised manuscript as follows:

“In this study, the Chinese Buddhist temple’s ringing bell, their most representative sound source, was selected. Other sound sources were not considered because these sounds were uncommon in the courtyard or had sound pressure levels that were too low.” (Please see 2. 2)

Point 4: In consideration of bell sound characteristics, is it meaningful to investigate speech intelligibility or musical clarity parameters?

Response 4: This is a good suggestion, in the revised paper the STI parameters (speech intelligibility) has been removed. Meanwhile, the authors considered that the bell could also be understood as a kind of music, so the C₈₀ parameters (musical clarity) in the paper have been retained.

Point 5: As shown in Fig. 5 and Table 1, it seems that the simulated results showed larger differences to the measured results in regard to JND values. Are there any elements to improve the simulation models?

Response 5: In the process of this study, numerous computer simulations were performed after field measurement, and the parameters used in the current study were the nearest simulated values to the measured results. One explanation about research limitation was added in the revised manuscript as follows:

“The simulation accuracy of this study had not entirely met the common acoustic criteria in interior space, which requires that the simulated error of RT should be less than its JND [41]. However, we consider the errors in this study to be within an acceptable range based on the following reasons: 1) There was a lack of related research about standard acoustic parameters of materials in ancient Chinese architecture. The sound absorption coefficients of ancient materials used in our simulation research were from those of relevant building materials in acoustic reference books, which may be different from the actual sound absorption coefficients of the site’s materials. 2) The measurements were conducted in outdoor spaces; the courtyard scale was large; reverberation resulted from multiple reflections; and the acoustic model simplified the building and the courtyard in the simulation process. These factors would affect the measurements and simulation accuracy in this study. 3) Relative values from courtyard sound field simulation results were compared and analysed, and the results of middle frequency (the bands of 500 Hz and 1000 Hz, which also is the main frequency range of human language), wherein errors were relatively small, were chosen as representative data. 4) The purpose of this study is not to obtain acoustic results for engineering calculations but to analyse characteristics of the courtyard sound field in Chinese Buddhist temples by means of comparing changing trends of the sound field.”(Please see 2. 3)

Point 6: The target venue is confusing. A standard model was selected as shown in Fig. 2 , and, the same model was investigated as shown in chapter 3. Then, three models as shown in Fig. 3 are employed only for acoustical fitting and measurement? If so, this part can be deleted since it has no direct relationship with the target venue. Acoustical fitting with measurement date should be the best, but if not, adopting settings from the references might be acceptable.

Response 6: Thanks for the suggestion. The original paper did not express this aspect clearly. Some explanations were added in the revised manuscript as follows:

“First, there is a lack of references for the simulation of a courtyard sound field in Han Chinese Buddhist temple for this paper. Moreover, it is prohibited to fully and systematically measure the sound field in a Buddhist temple as it is a sacred religious space in China. Therefore, in order to ensure the accuracy of the simulated temple sound fields in this research, courtyard sound field measurements were taken at Shenyang Imperial Palace, which has a similar architectural form to traditional Buddhist temples and uses comparable materials; notably, however, there are no Buddhist bell towers and drum towers in the courtyard of Shenyang Imperial Palace. Next, the sound absorption and scattering coefficients of traditional Chinese building materials were determined in the sound field simulation software by comparing simulated and measured data. Those coefficients will be used in the following simulation of Buddhist courtyard sound field.” (Please see 2. 3)

“Three courtyards in Shenyang Imperial Palace were selected and their sound fields were measured and simulated; further, results were cross-verified to ensure the accuracy and universality of the simulation.” (Please see 2. 3)

Point 7: In conclusion part, further application with the findings from this study should be more described. 

Response 7: According to this suggestion. One explanation was added in the revised manuscript as follows:

“Our research indicates that the temple layout of the Qing 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.” （please see 4. Conclusion）

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

The manuscript was improved from the initial submission. I appreciate the authors' efforts.