Sound Localization for Ad-Hoc Microphone Arrays

Reviewer 1

Response

This paper (Sound Localization for Ad-Hoc Microphone Arrays) provides little information. But, it is good motivation and result. So, I give Major Revision.

Thank you for your kind response.

The strength of the paper included: the topic is good and interesting.

Thank you for your kind response.

#1. Materials and Methods

What kind of "Development Language/Environment" did you use?
-Please add/more version and description.
-Environment explanation/presentation more.

The development language/environment has been explained in Section 3.1.

#2. 
Does the introduction provide sufficient background and include all relevant references? Must be improved 
Is the research design appropriate? Can be improved 
Are the methods adequately described? Can be improved 
Are the results clearly presented? Can be improved 
Are the conclusions supported by the results? Must be improved

The relevant sections have been improved.

#3. Contribution 
-It is almost impossible to understand the contribution of the paper.

The contributions of the study have been added in the section 1.

#4. Need "Related Work/Related Research" chapter.

Related work section has been added to the paper.

Need "Related Work/Related Research" chapter. Also, improve more related works, more to 10 new papers published from 2018~2021 by major publishers such as IEEE, ACM, Springer, Elsevier, MDPI, and Wiley. (Need new papers: 2018~2021)

#6. English language: English is good.
-English language and style are minor spell check required.

English language of the paper has been revised.

#7. If possible: Need Pseudocode or More Equation. 
-Sound Localization. (More Pseudocode or Equation.....)

-

#8.
What is Ad-Hoc Microphone Arrays?
-"Sound Localization" write/explain more.

The explanation has been added to the “Introduction” section.

#9. Conclusion part need
-You need to write more of the conclusion part.
-How about
    4. Conclusion (Need)
    5. Discussion
    6. Patents

Conclusion is added and the arrangement has been revised.

-Future work" write more. (Must be improved) 

Future work has been added

-Conclusions supported by the results. (Write more)

Conclusion has been added

Reviewer 2

Response

The authors discuss the interesting topic of sound source localization but fail to provide an appropriate literature review and references to relevant publications in the field. They also fail to discuss the importance of sound source quantification by using acoustic imaging techniques (i.e. not just the sound source location). In addition, the level of English is quite poor and requires better rewriting. I strongly recommend reviewing the work of other authors in the field since the proposed approach lacks novelty. In addition, no conclusion section is present and section 5 (patents) is not properly filled in and seems like a copy-paste from a template.

-Literature review has been added to the “Related Work” section.

-Literature review also sheds light on the acoustic imaging techniques.

-More references have been added.

-Conclusion section has been added

-Language of the paper has been revised.

-Patents section has been filled.

-The system brings novelty by targeting the following challenges in the domain of sound source localization:

    (i) Minimizing the number of microphones: The system uses four microphones as compared to six microphones which have been used in the previous studies, without compromising the performance of the system.

     (ii) Use of only 2 nodes, makes the system suitable to be used in hearing aids.

    (iii) System is designed to be used in reverberant environments. The input sound signals are mixed with noise content. The system generates a high accuracy (96.77%) even in the presence of noise.

    (iv) Novel methods have been used to calculate DOA and 3D coordinates of the sound source.

Reviewer 3

Response

Authors proposed sound localization method to easily determine the direction and distances of the sound sources. The direction of arrival method is used to differentiate the sound location with 3 dimension. They used four microphone arrays. Their accuracy of the system is 96.77% which is very good performance index. Sound signal amplitudes looks stable as shown in Figure 11.  However, there are some missing references. Therefore, the manuscript could be minor revision if authors follow the suggestions.

1. Please add some information in Author contribution, Funding, Acknowledgments, conflicts of interest section. Please correct others.

These sections are filled.

2. Please provide reduced journal names in the reference sections.

References have been updated

3. Please provide reduced conference names in the reference sections including date, city, and country information.

References have been updated

4.  Please increase label sizes of Figures 6 and 8.

Label sizes are enhanced.

5. In Figure 1, please increase font sizes of Figures 13 and 14.

Font size is increased.

6. Please clarify Figure 12 programming codes.

The code has been added to the Section 7 (Appendix)

7. Please provide the reference for the sentence ( Estimation The high-resolution method has limitations in terms of complex computations, and lack of consistent results ) with the reference (Stoica, Petre, and Kenneth C. Sharman. "Maximum likelihood methods for direction-of-arrival estimation." IEEE Transactions on Acoustics, Speech, and Signal Processing 38.7 (1990): 1132-1143. ) or another reference.

Reference has been added

8. Please provide the reference for the sentence (Widely used source localization methods work by determining the direction of sound waves coming from the source and finding the distances between sensors and source.) with the reference (Kundu, Tribikram. "Acoustic source localization." Ultrasonics 54.1 (2014): 25-38.) . or another reference.

Reference has been added

9. Please provide the reference for the sentence (Sound localization microphone arrays use multiple microphones that are used to perform different types of signal processing by utilizing the concept of phase difference of sound waves.  ) with the reference (Choi, Hojong, et al. "Active-beacon-based driver sound separation system for autonomous vehicle applications." Applied Acoustics 171 (2021): 107549.  )

Reference has been added

10. Please provide the reference for the sentence ( One such type of microphone arrays is the ad-hoc microphone arrays which can be best explained by the example of different laptops in a meeting. ) with the reference (Hennecke, Marius H., and Gernot A. Fink. "Towards acoustic self-localization of ad hoc smartphone arrays." 2011 Joint Workshop on Hands-free Speech Communication and Microphone Arrays. IEEE, 2011. ) or another reference.

Reference has been added

11. Please emphasize important values in the discussion section.

Numeric values indicating accuracy % and error factor have been added to the Discussion section.

Reviewer 1

Response

Dear Authors. 
The revision adequately address the concerns expressed in last review. So, I recommend that this revised manuscript can now be recommended for publication (Accept as is).

Thank you, for the recommendation.

Reviewer 2

Response

The quality of this manuscript is still not very high, although the authors have implemented some of the comments in the first review round. It is also nice to include an appendix with the MATLAB code employed.

An appendix with the MATLAB code has been added.

One important pitfall of the manuscript is that it fails to acknowledge the importance of sound source quantification (i.e. not just localization), which is crucial for many industrial and research applications. To comment on that, I recommend referring to recent publications such as:

Sound source quantification in the light of recent research has been discussed in Section 2 along with relevant references.

Sijtsma. P. and Stoker. R., Determination of Absolute Contributions of Aircraft
Noise Components Using Fly-over Array Measurements, in 10th AIAA/CEAS
Aeroacoustics Conference, May 10 - 12 2004, Manchester, United Kingdom
(2004) AIAA paper 2004–2958.

Sijtsma, P. "Phased array beamforming applied to wind tunnel and fly-over
tests", Tech. Rep. NLR-TP-2010-549 (National Aerospace Laboratory (NLR),
Anthony Fokkerweg 2, 1059 CM Amsterdam, P.O. Box 90502, 1006 BM Amsterdam, The Netherlands, 2010).

Merino-Martinez, R., Sijstma, P., Rubio Carpio, A., Zamponi, R., Luesutthiviboon, S., Malgoezar, A.M.N., Snellen, M., Schram, C. and Simons, D.G., “Integration methods for distributed sound sources,” International Journal of Aeroacoustics, Vol. 18, No. 4-5, pp. 444-469, 2019. DOI: 10.1177/1475472X19852945.

Please try to improve the quality of the figures used, especially the resolution and the proper use of axis labels. For example, Figs. 3 and 4 do not have a vertical axis label and Figs. 9-15 seem as simple screenshots straight from MATLAB. The use of high-quality figures is highly recommended (also to remove the gray background). Consider deleting Fig. 12 since it does not add important information that cannot be written down as text. Moreover, consider removing Fig. 16 since it does not seem relevant.

The figures have been updated.

Gray backgrounds have been removed. Resolution of images is enhanced and irrelevant figures are removed.

Axis labels in Figures 3 and 4 are added.