Placement Planning for Sound Source Tracking in Active Drone Audition

Round 1

Reviewer 1 Report

Dear Editor,

This paper presents a novel way to deploy multi-drones with multi microphones for sound source tracking. In this regard, the paper is very useful to utilize the idea and results in related areas.

The paper is suitable for publication in its present form after making minor corrections . To help this, I give some revision recommendations written below.

Best regards.

 Lee

Minor Recommendations;

1. It would be nice to add some references like below. Wang Lin et. al., 2018, Tracking a moving sound source from a multi-rotor drone

2. Because the results in this paper are purely based on numerical simulation,
the outdoor conditions (gust and flight path deviations etc.) in drone operation
should be considered.

3. If formulas are cited, please express their sources.

- The End -

Author Response

Dear Reviewer,

We would like to express our gratitude for your valuable feedback on our manuscript. We have taken your comments into account and believe that they have significantly improved our paper. Below, please find our responses to your comments point by point:

1. It would be nice to add some references like below. Wang Lin et. al., 2018, Tracking a moving sound source from a multi-rotor drone

Thank you for your kind recommendation. We appreciate your insightful recommendation and believe that this addition enriches the discussion within our work. We cite the reference as you can in citation No. 44.

2. Because the results in this paper are purely based on numerical simulation,
the outdoor conditions (gust and flight path deviations etc.) in drone operation
should be considered.

We greatly appreciate your insightful suggestion to conduct a real-world experiment to evaluate our proposed drone placement method. Your recommendation resonates with our long-term research goals, and we understand the importance of validating numerical simulation results with practical experimentation.

While our current research focuses on numerical simulation to evaluate the pure performance of the placement method, we acknowledge the potential uncertainties inherent in sound source tracking with drones, such as audio noise and GPS/IMU errors, which could affect the performance of our proposed method.

We believe your comment indeed highlights a critical aspect of our study that warrants a thorough investigation. In light of this, we have included in the end of our Conclusion section the potential challenges and limitations in a real-world setting as an avenue for future work.

3. If formulas are cited, please express their sources.

In response to your insightful suggestion regarding the citation of formulas, we have amended our manuscript to clearly indicate the original sources of all cited formulas. (Written in page 6)

Reviewer 2 Report

Scientifically, the paper could be more useful by presenting more real-time trials.

The quality of English can be improved before publication of this scientific paper. 

Author Response

Dear Reviewer,

We would like to express our gratitude for your valuable feedback on our manuscript. We have taken your comments into account and believe that they have significantly improved our paper. Below, please find our responses to your comment.

Comment: Scientifically, the paper could be more useful by presenting more real-time trials.
Response: I believe this real-time trials means real experiments in outdoor fields. This research has conducted numerical simulation to evaluate pure performance of the proposed placement method. Sound source tracking with drones contains a lot of uncertainty such as audio noise and GPS/IMU error. Of course the proposed method can be weak to these factors so we would like to state this investigation as our future work. (Written in the end of the Conclusion section)

Reviewer 3 Report

This paper presents a reasonable method to solve a real application problem. It is well-organized, clearly writing, and shows some interesting results that encouraged to be accepted with major revision. However, the commented questions need only to be answered.

1.    Please explicitly indicate and clarify the challenges this study aims to address. What are the challenges and why? Why cannot the previous studies well address these challenges?

2.    At the end of section 1, add a table that summarizes the advantages and disadvantages of existing methods facing the same problem. This way the reader would rapidly appreciate novelty of the paper.

3. The introduction and related work sections are very summarized, both of them need more discussion.

4.    More studies focused on the tracking should be discussed, e.g. 1) Intensive Review of Drones Detection and Tracking: Linear Kalman Filter Versus Nonlinear Regression, an Analysis Case, Archives of Computational Methods in Engineering, 2023. 2) Efficient vehicle detection and tracking strategy in aerial videos by employing morphological operations and feature points motion analysis, Multimedia Tools and applications, 2020. I cannot summarize all of them, but the authors are expected to reorganize these studies.

5.    Why do the authors depend on the particle filter strategy, there are more advanced tracking strategies that achieve the best result, such as optical flow and IMM filter.

6.     Figures 5,8,9,11 are not clearly shown.

7.  Please enrich the captions of all figures and tables for clarification.

8.   In the comparison to SOTA methods, more experimental results of other state-of-the-art methods should be given.

9.    I also find some grammar problems in this paper. The author needs to carefully check these low mistakes, which is very important for readers.

This paper presents a reasonable method to solve a real application problem. It is well-organized, clearly writing, and shows some interesting results that encouraged to be accepted with major revision. However, the commented questions need only to be answered.

1.    Please explicitly indicate and clarify the challenges this study aims to address. What are the challenges and why? Why cannot the previous studies well address these challenges?

2.    At the end of section 1, add a table that summarizes the advantages and disadvantages of existing methods facing the same problem. This way the reader would rapidly appreciate novelty of the paper.

3. The introduction and related work sections are very summarized, both of them need more discussion.

4.    More studies focused on the tracking should be discussed, e.g. 1) Intensive Review of Drones Detection and Tracking: Linear Kalman Filter Versus Nonlinear Regression, an Analysis Case, Archives of Computational Methods in Engineering, 2023. 2) Efficient vehicle detection and tracking strategy in aerial videos by employing morphological operations and feature points motion analysis, Multimedia Tools and Applications, 2020. I cannot summarize all of them, but the authors are expected to reorganize these studies.

5.    Why do the authors depend on the particle filter strategy, there are more advanced tracking strategies that achieve the best result, such as optical flow and IMM filter.

6.     Figures 5,8,9,11 are not clearly shown.

7.  Please enrich the captions of all figures and tables for clarification.

8.   In comparison to SOTA methods, more experimental results of other state-of-the-art methods should be given.

9.    I also find some grammar problems in this paper. The author needs to carefully check these low mistakes, which is very important for readers.

Author Response

Dear Reviewer,

We would like to express our gratitude for your valuable feedback on our manuscript. We have taken your comments into account and believe that they have significantly improved our paper. Below, please find our responses to your comments point by point:

1. Please explicitly indicate and clarify the challenges this study aims to address. What are the challenges and why? Why cannot the previous studies well address these challenges?
   

   In response to your request for clarity on the challenges our study aims to address, our research primarily seeks to tackle the issue of optimal placement of drones for effective sound source tracking. The performance of sound source tracking significantly depends on how the drones, carrying the microphone arrays, are positioned. This is the central challenge we aim to address.

   Previous studies have proposed various methods for sound source tracking. However, most of these studies have not fully considered or explored the impact of the placement of microphone arrays on the tracking results. The intricacies of array placement on mobile drones add complexity to the problem that has not been thoroughly investigated in the existing literature, forming the primary motivation for our research.

   By focusing on drone placement optimization, our work fills this gap and presents a solution that enhances the overall performance of sound source tracking, an aspect that prior research has not been able to address effectively.
   
   We have declared this point at the end of the Introduction section and Related Work section, and also declared that the proposed placement optimization method can be used for any sound source tracking method.
   

2. At the end of section 1, add a table that summarizes the advantages and disadvantages of existing methods facing the same problem. This way the reader would rapidly appreciate novelty of the paper.
   
   Thank you for your insightful suggestion. As recommended, we have now included a table at the end of section 2 instead of section 1 since it summarizes the related work. We believe that this addition will enable readers to rapidly appreciate the novelty of our work in comparison to existing methodologies. Your feedback has undoubtedly contributed to enhancing the readability and clarity of our paper.
   
   
3. The introduction and related work sections are very summarized, both of them need more discussion.
   

   Thank you for your valuable feedback. In response to your comments, we have expanded and enriched both the introduction and related work sections. They now contain more detailed discussions to provide a more comprehensive context for our study. We hope these enhancements provide a more in-depth understanding and clearer positioning of our research within the field. Your comments have greatly contributed to improving the quality of our manuscript.

4. More studies focused on the tracking should be discussed, e.g. 1) Intensive Review of Drones Detection and Tracking: Linear Kalman Filter Versus Nonlinear Regression, an Analysis Case, Archives of Computational Methods in Engineering, 2023. 2) Efficient vehicle detection and tracking strategy in aerial videos by employing morphological operations and feature points motion analysis, Multimedia Tools and applications, 2020. I cannot summarize all of them, but the authors are expected to reorganize these studies.
   

   In response to your suggestion regarding further discussion on visual tracking, we appreciate your viewpoint and understand the potential impact it could have on comprehensive drone tracking systems. However, the key objective of our present study is to enhance the placement optimization of multiple drones to improve the performance of sound source tracking.

   While the tracking aspect certainly plays a role, it is the strategic placement of drones, based on our proposed method, that we believe could lead to substantial improvements in tracking outcomes. The focus, therefore, is primarily on harnessing the benefits of optimal placement rather than developing new tracking techniques.

   We acknowledge the importance of visual tracking in broader drone tracking systems, and we will certainly consider this for future research, potentially integrating it with our placement optimization techniques to formulate a more comprehensive drone placement and tracking strategy. We have added this point to our future research directions.

   Thank you for your insightful recommendation, which has helped in expanding our perspective and potential future research avenues.

5. Why do the authors depend on the particle filter strategy, there are more advanced tracking strategies that achieve the best result, such as optical flow and IMM filter.
   

   In response to your suggestions concerning the enhancement of the particle filter tracking strategy using optical flow and Interacting Multiple Model (IMM) methodologies, we value your insights and acknowledge the potential these methods might bring to the tracking strategies.

   However, our tracking system is primarily based on audio signals, which makes the application of optical flow less suitable, as it fundamentally operates on visual data. With regard to the use of IMM, while it can be integrated with particle filter methods, the tracking methodology employed in this work is a continuation of our previously published research.

   The core novelty of the current study does not lie in the refinement of tracking methodologies but rather in the strategic placement optimization of drones to improve the performance of sound source tracking. Our primary focus has been on the exploration and enhancement of placement strategies.

   Nonetheless, we greatly appreciate your comments, and we believe they open up interesting avenues for potential future research, which might involve an in-depth exploration of different tracking methodologies, including IMM, in the context of audio-based drone tracking systems.

6. Figures 5,8,9,11 are not clearly shown.
   

   Thank you for your comment regarding the figures. We have carefully revised these figures to enhance their clarity. We believe that these modifications have substantially improved the presentation and interpretation of the associated data. We appreciate your valuable feedback in this matter.

7.  Please enrich the captions of all figures and tables for clarification.
   
   In response to your suggestion, we have expanded the descriptions in our figure captions to provide greater clarity and context. We believe this enhancement will make the figures more understandable and beneficial to the reader. We appreciate your attention to this detail and your guidance in improving the accessibility of our work.
   
   
8.  In the comparison to SOTA methods, more experimental results of other state-of-the-art methods should be given.
   

   In response to your suggestion to provide more experimental results of other state-of-the-art methods for comparison, we appreciate the valuable perspective this could offer. However, it's important to note that the focus of our current study is primarily on the optimization of drone placement to enhance sound source tracking, rather than on the sound source tracking process itself.

   The field of sound source tracking using multiple array systems, while promising, is still relatively nascent, and as such, there are limited state-of-the-art methods available for comparison. Our primary objective is to shed light on how strategic placement of drones can significantly improve tracking results.

   Nonetheless, we have endeavored to provide comparisons with relevant methods wherever feasible, and we acknowledge the importance of such comparative analyses in the broader scope of the field. We eagerly anticipate future advancements in this area that will provide more benchmarks for comprehensive comparison and further enhancement of our proposed strategy.

   Thank you for your valuable input and for helping us refine our future research direction.

9.   I also find some grammar problems in this paper. The author needs to carefully check these low mistakes, which is very important for readers.
   
   Thank you for your feedback. We have reviewed the manuscript for grammatical errors and revised them. We agree that clarity is essential and have made the necessary corrections to ensure our work is presented as clearly as possible. Your attention to detail is greatly appreciated.
   

Round 2

Reviewer 3 Report

Two issues need to be modified. 

1. The introduction section is very summarized and seems like an abstract, not introduction; it needs more discussion.
   

    

2. More studies focused on tracking or optimization in tracking should be discussed in the introduction or the related work section.

Two issues need to be modified. 

1. The introduction section is very summarized and seems like an abstract, not introduction; it needs more discussion.
   

    

2. More studies focused on tracking or optimization in tracking should be discussed in the introduction or the related work section.

Author Response

Dear Reviewer,

Thank you for the valuable time and effort you have invested in reviewing our paper. We appreciate your insightful comments and suggestions, which have helped us to enhance the quality and clarity of our manuscript. Below, we have addressed each of your points in detail:

1. The introduction section is very summarized and seems like an abstract, not introduction; it needs more discussion.

Thank you for your insightful feedback regarding the introduction section of our paper. We understand your concern that the original introduction was too concise and resembled an abstract, lacking in detailed discussion.

In response to your comment, we have enriched the introduction by providing a more comprehensive discussion about the core theme of our research. We have especially elaborated on the concept of "optimal placement" in the context of sound source tracking, which is the pivotal aspect of this study.

We believe this modification has significantly improved the depth and clarity of the introduction, thus giving the reader a better understanding of the paper's objectives and methodology.

2. More studies focused on tracking or optimization in tracking should be discussed in the introduction or the related work section.

Thank you for your valuable feedback regarding the need for additional references focusing on tracking and optimization in the context of our work.

In response to your suggestion, we have broadened our literature review to include more studies specifically related to sensor placement optimization, both in the fields of audio signal processing and visual processing.

We hope that these amendments enhance the paper's relevance and ties to the existing body of knowledge in the field. We appreciate your time and expert insight, which have undoubtedly helped improve the quality of our work.