Noise Impact Mitigation of Shopping Centres Located near Densely Populated Areas for a Better Quality of Life

Round 1

Reviewer 1 Report

This paper presents the numerical findings due to the insertion of a noise barrier between the residential buildings and a shopping center. The noise sources from the shopping center include air-conditioning systems at the roof and loading/unloading activities at the ground level. Other environmental noises were not considered in the numerical model. This paper should be categorized as a technical note or case study instead of a research article. As a research article, there is minimal novelty because such noise control technique is well-established. Usually, traffic noise is much louder than air-conditioning systems. Hence, the omission of this noise source may not entirely show that the residents are safe from the noise transmitted from the shopping center. Since there is no experimental validation, it is difficult to conclude whether the numerical findings indeed show that the residents are safe.

In summary, a rejection is recommended due to the lack of validation. The current numerical findings are not adequately validated and cannot be used to conclude that the residents are indeed exposed to acceptable noise levels according to the local regulations.

1. In general, there are several grammatical/punctuation errors and inconsistency in the main text. For example, in line 47, ‘estimate’ should be ‘estimates’; in line 49, ‘consist in’ should be ‘consists of’; line 52, ‘ show’ should be ‘shows’. These few are examples and there are more within the main text. For tasks that are completed, the description should be in past tense. It is recommended for the paper to undergo a round of review by a native speaker.
2. References to similar and past works are minimal. The introduction should be improved to provide a better background on how this work came about.
3. In line 44, it is mentioned that the noise signature of air-conditioning systems are tonal in nature. How about the loading/unloading activities? What is the problematic frequency range?
4. In line 48, what is VBEB? This acronym should be expanded during the first mention.
5. In line 52, it may be beneficial to consider indicating the version of the software.
6. In line 59, the SI unit for meter should be ‘m’. For consistency, if the authors wish to spell it in full, ‘dB’ should be spelled out as well as decibel.
7. In line 58, the EU directive should be cited on first mention rather than in line 70.
8. In line 73, the clock time should be standardized and the unit ‘h’ should be given for a 24-hour clock format. There is inconsistency because the AM/PM clock format is used in line 128.
9. In line 90, the test standard should be cited.
10. In line 89, ‘asses’ should be ‘assess’.
11. In figure 2, the measurement points should be labelled in figure 1 to mark out 1-10.
12. Sections 2 and 3 appear to be similar and may be grouped as the same section for numerical method. The current sections 2 and 3 are then presented as subsections 2.1 and 2.2, respectively.
13. In line 106, how were the two sound power levels obtained?
14. In line 112, the limitation of omitting traffic noise should be discussed in detail because this noise source could be much louder than the noise transmitted from the shopping center. This limitation is very critical in affecting the conclusion of the findings.
15. A description of the scenario should be indicated in the caption of figures 4-6 for clarity.
16. In figures 5-6, the outline of the noise barrier should be indicated clearly for clarity.
17. In line 141, the improved results cannot be explained simply by claiming that it is due to reduced leakages and improved effectiveness of the sound absorption. The improved results should be explained based on the classical noise barrier theory where the noise reduction may be better when the barrier is placed nearer to the source. The current explanation may not be entirely sound.
18. In figure 7, why measurement points 3-6 show much more reduction compared to the other points?
19. In figure 9, why is the noise level at measurement points 4-5 especially low compared to the other points? It is difficult to understand why the ambient noise level is at 5 dBA. The typical background noise should be much higher as shown by other measurement points.

Author Response

Author Response File: Author Response.pdf

Reviewer 2 Report

This work studies the impact of noise by shopping centres on densely populated residential area by simulation. The topic fits into the scope of the journal and special issue, however, due to the lack of clarification and justification, the submission is weak and require major revision before the publication.

1. Introduction: Introduction is too brief and does not give enough information about the motivation, importance, merit, and clarification of the target of this study. Also, the references cited herein were rather old and do not reflect the state of the arts in this field. The authors are invited to enrich this section to give more clear explanation on the context of this work: (1) add more survey on the noise impact problem by shopping centres; (2) clarification of the purpose and target of this work; (3) cite more up-to-date references; (4) justification of the methodology employed in this work.
2. Undefined acronyms are found in the text: for example 'VBEB' in Introduction is not given its definition.This is also a cause of low readability.
3. Three scenarios are studied in this work, according to the last paragraph of Introduction. However, this part should be either fully detailed or briefly outlined and add full details in the following section. In the current version, this paragraph is not enough for correct understanding.
4. Sec 2 is quite confusing. EU DIRECTIVE should be explained more in detail because readers outside EU may not be familiar. Also, EU DIRECTIVE encourage to use 6m high receivers for assessment, but the authors choose different height. This point is crucial and should be explained with evidence and full discussion. 
5. IMMI software is not understandable. This needs more description. On what physical principle this works is of vital importance to evaluate the results. The authors are invited to add more profound discussion on how this software works.
6. Temperature and humidity are set to 10C and 70%. Why do the authors choose these values? Please add explanation.
7. Figure 1 and after. Did the authors validate or confirmation of the accuracy of the simulation? Of course, one can discuss this problem with only relative values, however, the reviewer invites authors to add some information about the validity of the simulation.
8. This reviewer suggests to change the colours of sound level in all figures (for example, Figure 4). Red coloured buildings are disturbing noise level contour maps.
9. In all results, the authors only mention 'noise level' or SPL or similar words. Are they RMS SPL, LAeq, or other measures such as Ldn, Lden etc? Please give what measures the authors are using in the text and all figures. This clarification is quite important.
10. For example in Figure 2, 'day period' and 'night period' are indicated. Please specify the time (and the type of the level as well).
11. LL117-: Three scenarios are indicated. They are better itemised and if possible please use figures wherever applicable.
12. Conclusion should be more explaining: please outline the work presented, and highlight the main results with main points of discussion.

Author Response

Pt.1 The introduction was completed with up-dated information and clarifications.

Pt. 2 The acronym VBEB was detailed.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The authors have satisfactorily addressed my comments and the quality of the manuscript has certainly improved after the revision. However, I recommend the authors to run through the manuscript with an English native speaker to improve the language. Following which, the manuscript can be accepted.

Reviewer 2 Report

The authors made a great effort to improve the quality of the paper, addressing all points raised. Therefore, this reviewer endorses the publication of this version.