Sound Absorption Properties of Charcoal Made from Wood Waste
Round 1
Reviewer 1 Report
I have reviewed the submitted manuscript titled “Theoretical and experimental studies on the sound absorption of wood-waste by using an acoustic model and impedance tube technique”. i can not support the acceptance of this manuscript as I believe there is a major problem here: lack of novelty. My first and primary concern lies in the novelty of this work, as i feel that the novelty issue has not been sufficiently highlighted in the current version. An important question shall be answered: does this work fill up some knowledge gaps which previous articles cannot address? I think that there is nothing innovative about the experimental methods or theoretical models. Repeats existing knowledge and does not refine conclusions to a level of importance that can significantly impact the subject area. The authors need to provide the contributions of this study more specific.
Author Response
Response to Reviewer 1 Comments
Thank you for considering publishing our manuscript on the topic of the “Experimental study of charcoal sound absorption properties made of wooden waste”. The manuscript was changed according to your comments.
A new research novelty on granular charcoal has added. The research found few studies on the sound absorption of charcoal. Granular charcoal from wood biomass is a renewable material whose sound absorption characteristics are high enough to make it an effective sound-absorbing material. Granular charcoal has properties that are more effective on absorption than wood same species. Our research shows that granulated charcoal is effective acoustic. The theoretical model on wood species was overthrow from the articles. The newly collected data of recycling sustainable material granular charcoal without any chemical substances. In the article wooden sound absorption properties improved by heat-treated.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The paper investigated the sound absorption coefficients of three species of wood by measured and predicted values. A major revision is necessary, mainly in the grammar and on the writing. In the current form, the paper cannot be accepted.
It is also necessary to exemplify the use of the studied species. Why did the author choose these species? Will they be used as sound absorbent materials in real environments? What about the other properties of that scheme for acoustical treatments, such as fire and biological resistance? Are the species used in wood-based composite?
I strongly recommend the study and consideration of the following papers: Botterman et al (2018) - 10.1016/j.apacoust.2017.07.017 - and Ribeiro et al (2021) - 10.1016/j.apacoust.2021.107967.
I suggest some points that might be reviewed:
L15 and L16: Italic style for the species designation
L18: check the word "those"
L21: check the sentence
L25: what is 0.27 samples? It wasn't presented in the abstract before. Clarify that information.
L37: change the references from [1,2,3,4] to [1-4].
L78 and L79: there are other parameters, such as viscous and thermal characteristics lengths and the tortuosity. You should cite and describe these parameters as well.
L158 The Delany-Bazley-Miki model can also produce effective densities that are physically incorrect at low frequencies - check R. Kirby, “On the modification of Delany and Bazley formulae”, Appl. Acoust., 86, 47–9 (2014). According do Cox and D’Antonio (2016)[1]: “The Wilson relaxation model provide similar results to other empirical models and has the advantage that at low frequency the acoustic parameters are limited to correct physical values”. It is necessary to apply other models in order to investigated which one provides the best fit (i.e. Wilson or JCAL-Johnson et al. Champoux-Allard, Lafarge et al), otherwise the research is poor in results and discussion. There are empirical equations on the literature linking porosity, tortuosity and airflow resistance. The authors could use these equations to predict the other properties and apply other models.
L310 Please check the word “experemental” within the Figures.
L371 The authors should consider that not only Density is the reason for the sound absorption values. There are other parameters in wood, such as structural morphology and air permeability – check the paper of Kolya and Kang (2020) - 10.1016/j.apacoust.2020.107475.
Generally, the paper must be highly improved and resubmitted for a new consideration.
[1] Cox, Trevor, and Peter d’Antonio. Acoustic absorbers and diffusers: theory, design and application. Crc Press, 2016.
Author Response
Response to Reviewer 2 Comments
Thank you for considering publishing our manuscript on the topic of the “Experimental study of charcoal sound absorption properties made of wooden waste”. The manuscript was changed according to your comments.
- The species chosen because it is widespread in this region uses in industry from which we can get the waste. We changed the novelty the granular charcoal can be uses in real environment can used as sound absorbent materials, the material acoustical a properties high to uses it as acoustic treatment. The species of granular charcoal used with successfully in composite structure.
- The article of Botterman et al. 2018 studied and added to the references list.
- The Delany-Bazley-Miki model removed instead of model added new researches on sound absorption properties of granular charcoal. The Delany-Bazley-Miki model nothing innovative about wood studies.
- The air flow resistivity, densities, grain size distribution parameters in wood and granular charcoal was consider in studies.
Reviewer 3 Report
This paper conducted an experimental investigation of the sound absorption coefficient of three types of wood samples. The experimental design is reasonable, and the measurement results are also valuable. Some revisions should done.
1. Figure 5 is too rough, and the value of the horizontal coordinates has no units, so it should be redrawn.
2. What’s the purpose of the measurement of airflow resistivity, and what’s the relationship between the airflow resistivity and the sound absorption coefficient?
Author Response
Response to Reviewer 3 Comments
Thank you for considering publishing our manuscript on the topic of the “Experimental study of charcoal sound absorption properties made of wooden waste”. The manuscript was changed according to your comments.
- The materials' airflow resistivity granular charcoal specimen has a lower value of airflow resistivity than wood and tends to have a higher sound absorption coefficient.
- Some additional experimental research on study of charcoal added to the article.
Round 2
Reviewer 1 Report
This new version of the paper is in according to reviewer's comments.
Author Response
Response to Reviewer 1 Comments
Thank you for considering publishing our manuscript on the topic of the “Sound absorption properties of charcoal made from wood waste”. The manuscript was changed according to your comments.
The manuscript was submitted for review in language editing services. Linguistic corrections are indicated in the manuscript.
Reviewer 2 Report
The paper investigated the use of charcoal mixed with wood as a sound absorbent material. There is a lack of scientific data concerning the material. Can it be applied in a real environment? The discussion is very poor for a scientific paper.
Control is missing in the experiments.
Author Response
Response to Reviewer 2 Comments
Thank you for considering publishing our manuscript on the topic of the “Sound absorption properties of charcoal made from wood waste”. The manuscript was changed according to your comments.
The manuscript was submitted for review in language editing services. Linguistic corrections are indicated in the manuscript.
A not significant amount of scientific data concerning the granular charcoal material is the opportunity to research this material. Charcoal could use such as a composite with building materials. A solid fraction of charcoal could use for indoor acoustic as a sound-reflected material. To the discussion was added additional data about the acoustic properties of materials.
The sound absorption coefficient of materials measured in the impedance tube follows equations. The measurements were repeated 3 times for 12 wood samples (10, 18, 25, and 30 mm) thick and 3 charcoal samples of 25 mm thickness.
Reviewer 3 Report
No more comments.
Author Response
Response to Reviewer 3 Comments
Thank you for considering publishing our manuscript on the topic of the “Sound absorption properties of charcoal made from wood waste”. The manuscript was changed according to your comments.
The manuscript was submitted for review in language editing services. Linguistic corrections are indicated in the manuscript.
Round 3
Reviewer 2 Report
The paper was improved and the authors justified some questions made by this reviewer. I suggest a minor revision and the consideration of the following topics:
L236 - What about the humidity of the samples for bulk density measurements?
L260 - Figure 4: the graphs should be improved. It is impossible to read the data
L276 - Figure 5: the graphs should be improved. The lines are thick.
