Design and Evaluation of Noise Simulation Algorithm Using MATLAB Ray Tracing Engine for Noise Assessment and Prediction
Round 1
Reviewer 1 Report
Comments and Suggestions for Authors1) A clearer focus on the specific gap this study addresses and its novelty could strengthen the introduction (eg. reference and clear advantages over the existing noise prediction techniques, such as the SCANAM and BIM simulation).
2) Additional details on the assumptions made during simulation (e.g., environmental factors) could improve reproducibility of this study.
3) Some recent studies on similar simulation tools might strengthen the literature.
The quality of English is generally good, but some sentences are overly complex and could be more condensed.
eg.
The measurements obtained throughout the factory are tabulated and represented in a sound level map, as illustrated in Figure 11, which provides a comprehensive overview of the noise environment within the factory.
Author Response
Comments 1: A clearer focus on the specific gap this study addresses and its novelty could strengthen the introduction (eg. reference and clear advantages over the existing noise prediction techniques, such as the SCANAM and BIM simulation).
Response 1: Thank you for pointing this out. We agree with this comment. Firstly, SCANAM method is measuring the noise levels around the floorplan and mapping it out. This doesn’t include prediction. If the factory is planning to add another machine into their line, we can predict how its going to be. BIM and other simulation methods requires expensive software and skilled workers. The research is on developing an open-sourced easy-to-use software which outputs a simple pass or fail. The output will compare the data with national standards. This makes it easier for the worker.
Comments 2: Additional details on the assumptions made during simulation (e.g., environmental factors) could improve reproducibility of this study.
Response 2: Agree. Additional details on the simulation set-up and environmental factors would be added into the manuscript. As for now, the assumption made is no external sound from outside of the building is entering the building as the simulation is only done in an enclosed space. Therefore, a safety factor could be added to the final output. The floor, walls and ceiling materials, the dosage percentage and the number of reflections can be tweaked by the user for specific use cases.
Comments 3: Some recent studies on similar simulation tools might strengthen the literature.
Response 3: Agree. More literature review will be done on recent studies on Noise Hazard and the relatable ones will be added into the paper.
- Response to Comments on the Quality of English Language
Point 1: The quality of English is generally good, but some sentences are overly complex and could be more condensed.
- The measurements obtained throughout the factory are tabulated and represented in a sound level map, as illustrated in Figure 11, which provides a comprehensive overview of the noise environment within the factory.
Response 1: Yes, we do agree. We have gone through the whole paper improving this issue at several places. Thank you for the review.
Additional clarifications
The research is based on a grant by the government which focuses on improving the noise safety in small manufacturing factories. The identified issue is lack of funding and skilled employee. Therefore, the development of an open-sourced easy-to-use noise simulation software which outputs a simple pass or fail is important. The software integrates the national standard and lets the user know if it’s safe or not. The code will be exported as a standalone application and distributed to the small manufacturing industries as their first level of defence against noise hazard.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsThis paper conducted a noise simulation algorithm using matlab ray tracing engine for noise assessment and prediction. Although this paper does not have much theoretical or methodological innovations, the algorithm constructed has certain engineering value for the processing and display of noise testing data in practical engineering problems. It should be revised before publication.
1. The abstract has too many words. It is recommended that the author streamline it and express the main work and innovative points clearly.
2. Introduction. The last paragraph is from the submission template and is not related to this paper. The author should delete it.
3. The resolution of the full text images is too low, and the authors should ensure that the resolution of each image is above 300 * 300dpi.
4. The brand, model, and other detailed information of the instruments used by the authors for acoustic testing should be provided.
5. What is the principle of 3D version of ray diagram and how does it fit the overall noise distribution through discrete data points?
6. Whether the author compares the calculation results of his own algorithm with those of other commercial software is related to the progressiveness of the algorithm developed by the author.
Author Response
Comments 1: The abstract has too many words. It is recommended that the author streamlines it and express the main work and innovative points clearly.
Response 1: Thank you for pointing this out. We agree with this comment. Therefore, we have made the abstract more concise focusing on the novelty of the research, which is the development of an open-sourced easy-to-use noise simulator which compares its output with the national standards. The simulator then suggests ways to overcome the problem based on national recommendations.
Comments 2: Introduction. The last paragraph is from the submission template and is not related to this paper. The author should delete it.
Response 2: Agree. We missed this out while transferring the article into the template. We have deleted the paragraph.
Comments 3: The resolution of the full text images is too low, and the authors should ensure that the resolution of each image is above 300 * 300dpi.
Response 3: Agree. We have updated some of the pictures with higher quality ones. For further improvement, we will also attach the image files as additional documents in the submission form.
Comments 4: The brand, model, and other detailed information of the instruments used by the authors for acoustic testing should be provided.
Response 4: We have provided this information at section 2.3.2, line 455 to 457. “The measuring device employed for this assessment was the NIOSH Sound Level Meter (SLM) application, utilized in conjunction with an i436 external microphone, which is a calibrated measurement microphone adhering to the IEC 61672 Class 2 sound level meter standard.”
Comments 5: What is the principle of 3D version of ray diagram and how does it fit the overall noise distribution through discrete data points?
Response 5: The 3D version of ray tracing is done to address the noise reflection on the wall and ceiling apart from the walls. This is because of their respective distance and material plays a huge role in the final output. The discrete data points represent the receiver’s location which must be optimised.
Comments 6: Whether the author compares the calculation results of his own algorithm with those of other commercial software is related to the progressiveness of the algorithm developed by the author.
Response 6: Most of the commercial software are highly priced and not easily attainable in our country. Therefore, the verification method used are manual calculations and experimental data from measuring real world data. These methods are explained in section 2.2 and 2.3.
Additional clarifications
The research is based on a grant by the government which focuses on improving the noise safety in small manufacturing factories. The identified issue is lack of funding and skilled employee. Therefore, the development of an open-sourced easy-to-use noise simulation software which outputs a simple pass or fail is important. The software integrates the national standard and lets the user know if it’s safe or not. The code will be exported as a standalone application and distributed to the small manufacturing industries as their first level of defence against noise hazard.
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsThe paper discusses the applications of raytracing in the workplace.
Raytracing is applied with a matlab routine: this routine should be explained.
Furthermore, raytracing techniques are well established for architectural acoustics for the acoustic correction of closed environments and the design of theatres.
There are many commercial software (odeon, cadna, ramsete,..) that develop the image and raytracing technique for the simulation of the sound field.
It should be considered that when simulating an environment, calibration must be performed, generally the measured T30 must in equal with the simulated T30 at the frequency of ISO 3382.
The geometry of the rooms must be built.
The sound absorption coefficient of the walls must be known.
Machines cannot be simulated as point sources.
Author Response
Comments 1: The paper discusses the applications of raytracing in the workplace. Raytracing is applied with a MATLAB routine: this routine should be explained.
Response 1: Thank you for pointing this out. We agree with this comment. Therefore, we will explain it here and add it to the manuscript. The raytracing is done using the Shooting and Bouncing Rays (SBR) method. The SBR method launches many rays from a geodesic sphere centred at the noise source. The geodesic sphere enables the model to launch rays that are approximately uniformly spaced. Then, the method traces every ray from the source and can model different types of interactions between the rays and surrounding objects, such as reflections and edge diffractions. When a ray hits a flat surface, the ray reflects based on the law of reflection. When a ray hits an edge the ray spawns many diffracted rays based on the law of diffraction. Each diffracted ray has the same angle with the diffracting edge as the incident ray. The diffraction point then becomes a new launching point and the SBR method traces the diffracted rays in the same way as the rays launched from source. A continuum of diffracted rays forms a cone around the diffracting edge, which is commonly known as a Keller cone. All the rays from the source to the receiver is then isolated and calculated based on the noise absorption coefficient and the inverse square law. Then they are all summed up for the final value.
Comments 2: Furthermore, raytracing techniques are well established for architectural acoustics for the acoustic correction of closed environments and the design of theatres. There are many commercial software (odeon, cadna, ramsete,..) that develop the image and raytracing technique for the simulation of the sound field.
Response 2: Agree. The objective of this research is to develop an open-sourced easy to use noise simulation software with the national standards integrated. This is because of the research done identifying the reason behind the high number of occupational noise-induced hearing loss in our country is lack of funding and skilled workers. Therefore, this would be the first level of defence against noise hazard mitigation.
Comments 3: It should be considered that when simulating an environment, calibration must be performed, generally the measured T30 must in equal with the simulated T30 at the frequency of ISO 3382.
Response 3: Agree. But in this case, the simulation is done merely focusing on noise as a hazard and the final output comes with a safety factor to overcome environmental factors from outside the building. The software is targeted to small manufacturing industries for floor plan optimisation and staying within the national standards. The measured value is from a well calibrated measuring device and the simulation is build on the MATLAB raytracing engine which proves to be accurate. This comment will definitely be taken into consideration into further enhancing this research.
Comments 4: The geometry of the rooms must be built. The sound absorption coefficient of the walls must be known.
Response 4: Agree. In this simulation, the geometry of the floorplan is built and exported as a stl file. The material of the smooth factory walls is made from concrete. Therefore, we set it to represent the standard value of concrete walls.
Comments 5: Machines cannot be simulated as point sources.
Response 5: Agree. We measured the sound output of the machine in work over a long period of time. We managed to get a lot of data from there, mainly the average SPL. This is then used as the SPL value for the noise source in the simulation.
Additional clarifications
Thanks for the comments. Everything is considered and added into the manuscript respectively. This research is based on a grant by the government which focuses on improving the noise safety in small manufacturing factories. The identified issue is lack of funding and skilled employee. Therefore, the development of an open-sourced easy-to-use noise simulation software which outputs a simple pass or fail is important. The software integrates the national standard and lets the user know if it’s safe or not. The code will be exported as a standalone application and distributed to the small manufacturing industries as their first level of defence against noise hazard.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
Comments and Suggestions for AuthorsIt can be accepted.
Author Response
Thank you so much for taking your time to review my article. I really appreciate your help.
Reviewer 3 Report
Comments and Suggestions for AuthorsThe paper could be accepted as a technical note.
The values ​​are in dB, but for environmental noise you use dBA you should make this correction.
In the case of industrial noise you also use dBC.
You should explain the reason for dBA and not dB.
Table 1, remove Permittivity Conductivity. They are not acoustic quantities.
You report only one value of the absorption coefficient. But ISO 3382 considers from 125 Hz to 4000 Hz in octave bands. Do you use an average value? How did you obtain it?
Machines in industry work at high frequency and low frequency, how do you do this simplification?
If you use dBA you can use only one value. dBA reduces low frequencies and you could work from an average value from 500 Hz to 4000 Hz.
Without forgetting that machines scatter sound and the sound spreads and is not reflected.
You must make this consideration.
You should have compared your software with other ray tracing. (Rindel, Farina, Iannace, Bevilacqua used ray tracing software, refer to these papers for completeness.)
You get a 3dB offset, looks good.
Author Response
Comments 1: The values are in dB, but for environmental noise you use dBA you should make this correction. If you use dBA, you can use only one value. dBA reduces low frequencies, and you could work from an average value from 500 Hz to 4000 Hz. In the case of industrial noise, you also use dBC. You should explain the reason for dBA and not dB.
Response 1: Thank you for pointing this out. We use dB in the calculations, MATLAB code and throughout the paper. The dBA was at the introduction part referencing to another paper stating that the CNC machine noise levels are often higher than the safe level which they described using dBA.
Comments 2: Table 1, remove Permittivity Conductivity. They are not acoustic quantities.
Response 2: Agree. Thank you for pointing this out. We have removed Permittivity and Conductivity as you requested as they aren’t acoustic quantities.
Comments 3: You report only one value of the absorption coefficient. But ISO 3382 considers from 125 Hz to 4000 Hz in octave bands. Do you use an average value? How did you obtain it? Machines in industry work at high frequency and low frequency, how do you do this simplification?
Response 3: Agree. In this case, we used the average absorption coefficients of the materials across the frequency. This was done because the slight difference in the final value isn’t crucial for the objective of this tool. This tool is meant to estimate the noise level with a safety margin to ensure the floorplan of the factory remains in the safe zone.
Comments 4: Without forgetting that machines scatter sound and the sound spreads and is not reflected. You must make this consideration.
Response 4: Agree. We measured the sound output of the machine in work over a long period. From here, we got a lot of data, mainly the max SPL, the average SPL and the runtime of the machine. This is then used as the SPL and dosage value for the noise source in the simulation.
Comments 5: You should have compared your software with other ray tracing. (Rindel, Farina, Iannace, Bevilacqua used ray tracing software, refer to these papers for completeness.)
Response 5: Thank you for the suggestion. We will review these articles and improve our paper accordingly to make it more complete.
Additional clarifications
Thanks for the comments. Everything is considered and added into the manuscript respectively. This research is based on a grant by the government which focuses on improving the noise safety in small manufacturing factories. The identified issue is lack of funding and skilled employee. Therefore, the development of an open-sourced easy-to-use noise simulation software which outputs a simple pass or fail is important. The software integrates the national standard and lets the user know if it’s safe or not. The code will be exported as a standalone application and distributed to the small manufacturing industries as their first level of defence against noise hazard.
Author Response File: 
Author Response.docx
Round 3
Reviewer 3 Report
Comments and Suggestions for Authorswrite 36.4 dB no 36.41 dB
use one decimal
accept as technical note
