Acoustic and perceptual impact of face masks on speech: A scoping review

Gursharan Badh; Thea Knowles

doi:10.1371/journal.pone.0285009

Peer Review History

Original SubmissionMarch 30, 2022
9 Nov 2022 Decision Letter - Andreas Buechner, Editor PONE-D-22-09426Acoustic and perceptual impact of face masks on speech: A scoping reviewPLOS ONE Dear Dr. Knowles, Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process. Please submit your revised manuscript by Dec 24 2022 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file. Please include the following items when submitting your revised manuscript: A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'. A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'. An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'. If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter. Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter. If applicable, we recommend that you deposit your laboratory protocols in protocols.io to enhance the reproducibility of your results. Protocols.io assigns your protocol its own identifier (DOI) so that it can be cited independently in the future. For instructions see: https://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols. Additionally, PLOS ONE offers an option for publishing peer-reviewed Lab Protocol articles, which describe protocols hosted on protocols.io. Read more information on sharing protocols at https://plos.org/protocols?utm_medium=editorial-email&utm_source=authorletters&utm_campaign=protocols. We look forward to receiving your revised manuscript. Kind regards, Andreas Buechner Academic Editor PLOS ONE Journal Requirements: When submitting your revision, we need you to address these additional requirements. 1. Please ensure that your manuscript meets PLOS ONE's style requirements, including those for file naming. The PLOS ONE style templates can be found at https://journals.plos.org/plosone/s/file?id=wjVg/PLOSOne_formatting_sample_main_body.pdf and https://journals.plos.org/plosone/s/file?id=ba62/PLOSOne_formatting_sample_title_authors_affiliations.pdf 2. We note that you have stated that you will provide repository information for your data at acceptance. Should your manuscript be accepted for publication, we will hold it until you provide the relevant accession numbers or DOIs necessary to access your data. If you wish to make changes to your Data Availability statement, please describe these changes in your cover letter and we will update your Data Availability statement to reflect the information you provide. 3. Please include captions for your Supporting Information files at the end of your manuscript, and update any in-text citations to match accordingly. Please see our Supporting Information guidelines for more information: http://journals.plos.org/plosone/s/supporting-information. 4. Please review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text, or remove these references and replace them with relevant current references. Any changes to the reference list should be mentioned in the rebuttal letter that accompanies your revised manuscript. If you need to cite a retracted article, indicate the article’s retracted status in the References list and also include a citation and full reference for the retraction notice. [Note: HTML markup is below. Please do not edit.] Reviewers' comments: Reviewer's Responses to Questions Comments to the Author 1. Is the manuscript technically sound, and do the data support the conclusions? The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented. Reviewer #1: Yes Reviewer #2: Yes ******** 2. Has the statistical analysis been performed appropriately and rigorously? Reviewer #1: Yes Reviewer #2: N/A ****** 3. Have the authors made all data underlying the findings in their manuscript fully available? The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified. Reviewer #1: Yes Reviewer #2: Yes ****** 4. Is the manuscript presented in an intelligible fashion and written in standard English? PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here. Reviewer #1: Yes Reviewer #2: Yes ****** 5. Review Comments to the Author Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters) Reviewer #1: The article summarizes current evidence about facemasks’ impact on communication, examining effects on acoustics, intelligibility, and voice production. The study presents the results of original research, which to my knowledge have not been published elsewhere. The problem is exhaustively illustrated in the introduction and a good overview of the type of existing masks is provided. The methods are extensively described and appear rigorous. The methods follow high technical standards. Supplemental materials provide all data to better know the research and selection process. The “result and discussion” section is subdivided into coherent subsections covering all the relevant aspects of the issue, providing a clear and complete state-of-the-art about the topic. In the “perceptual outcomes of masks” section, I suggest focusing on the impact of facemasks on speech perception according to the hearing status of the listener, since this aspect has gained popularity in the scientific community and public opinion as well and deserves some adjunctive detail. On this latter point, I think that the work of Tofanelli et al. could add some valuable insights (Tofanelli M, Capriotti V, Gatto A, Boscolo-Rizzo P, Rizzo S, Tirelli G. COVID-19 and Deafness: Impact of Face Masks on Speech Perception. J Am Acad Audiol. 2022 Feb;33(2):98-104. doi: 10.1055/s-0041-1736577.) The limitations of the study are clearly stated. The conclusions are coherent with the shown data. The figures are clear and easily understandable. Minor points: Line 440: What do you mean with Fivexx? I believe this is a typing mistake. If so, please correct it. Otherwise, the phrase needs clarification. Lines 590-593: The repeated “xx” are probably typing mistakes, that need to be fixed. In summary, given the large and heterogeneous field of investigation and the effective synthesis provided, I commend the authors for their great efforts in this study. The article is easily readable and written in comprehensible English. Once fixed the abovementioned small issues, I consider the work worthwhile to be published. Reviewer #2: The authors present a literature review on the acoustic and perceptual effects of face masks on speech. It does a good job summarizing the key results for researchers who are new to the topic, though I would have liked to see more analysis of the conflicting results in the literature. For example, is there a pattern of methodological differences between studies that did or did not find significant impacts on speech intelligibility? I would also appreciate more analysis of the studies' methodology overall (microphone placement, live talkers vs. mannequins, live listening vs. recordings, how to control for audio/visual variables, how to report attenuation data), since in this new research area there are not yet established best practices. Notably, many of the studies were conducted during lockdown conditions and had to conduct human-subjects experiments remotely. Specific comments: - The paper needs some copyediting. There are several "XX" placeholders and one "[CITE]" placeholder. The authors are inconsistent in their formatting of numbers in the text. The usual practice is to write out numbers less than ten, and to never start a sentence with a numeral. - Line 126-134: This paragraph does not seem to fit into the surrounding paragraphs, which have already introduced respirators. The introduction is choppy overall, with some concepts introduced multiple times. - Line 164: The purported benefits of transparent masks for listeners with hearing loss are controversial, as many of the reviewed articles point out. They can be helpful in some cases but not others, depending on the relative impact on auditory and visual cues for a particular mask and their relative importance for a particular listener. I would word this sentence more carefully. - Line 522: As written, it appears that the subject of the verb "dampened" is "attenuation", which is not what the authors intend to convey. - In the audio-visual section, it is not clear exactly what is being compared in each study. There are many variables that might be manipulated in such a study: presenting audio-only recordings with/without masks, audio-visual recordings with/without masks, masked audio imposed on unmasked video, unmasked audio on masked video, unmasked recordings processed to simulate masks, etc. It is unclear whether all the studies in this section were measuring the same thing, so please provide more detail. - In the section on vocal intensity, what exactly is being measured? If intensity is the overall acoustic energy in the signal, we would not expect most masks to have a measurable effect. Most energy in speech is concentrated at low frequencies, where masks are mostly transparent; even if a mask completely blocked all high frequencies, that would barely change the total energy. Human talkers might increase their effort while wearing a mask, which would affect the overall intensity, but it is not clear if that is what is being studied by all the papers in this section. - Table 3 is difficult to read. It is too cluttered to effectively convey information. Perhaps it needs to be broken up, or at last reformatted. ****** 6. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files. If you choose “no”, your identity will remain anonymous but your review may still be made public. Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy. Reviewer #1: No Reviewer #2: No ******** [NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.] While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org. Please note that Supporting Information files do not need this step. https://doi.org/10.1371/journal.pone.0285009.r001
Revision 1
6 Feb 2023 Author Response See also the uploaded Response to Reviewers document. ---- PONE-D-22-09426 Acoustic and perceptual impact of face masks on speech: A scoping review PLOS ONE Reviewers' comments: Reviewer's Responses to Questions Comments to the Author 1. Is the manuscript technically sound, and do the data support the conclusions? The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented. Reviewer #1: Yes Reviewer #2: Yes 2. Has the statistical analysis been performed appropriately and rigorously? Reviewer #1: Yes Reviewer #2: N/A 3. Have the authors made all data underlying the findings in their manuscript fully available? The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified. Reviewer #1: Yes Reviewer #2: Yes 4. Is the manuscript presented in an intelligible fashion and written in standard English? PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here. Reviewer #1: Yes Reviewer #2: Yes 5. Review Comments to the Author Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters) Reviewer #1: The article summarizes current evidence about facemasks’ impact on communication, examining effects on acoustics, intelligibility, and voice production. The study presents the results of original research, which to my knowledge have not been published elsewhere. The problem is exhaustively illustrated in the introduction and a good overview of the type of existing masks is provided. The methods are extensively described and appear rigorous. The methods follow high technical standards. Supplemental materials provide all data to better know the research and selection process. The “result and discussion” section is subdivided into coherent subsections covering all the relevant aspects of the issue, providing a clear and complete state-of-the-art about the topic. In the “perceptual outcomes of masks” section, I suggest focusing on the impact of facemasks on speech perception according to the hearing status of the listener, since this aspect has gained popularity in the scientific community and public opinion as well and deserves some adjunctive detail. On this latter point, I think that the work of Tofanelli et al. could add some valuable insights (Tofanelli M, Capriotti V, Gatto A, Boscolo-Rizzo P, Rizzo S, Tirelli G. COVID-19 and Deafness: Impact of Face Masks on Speech Perception. J Am Acad Audiol. 2022 Feb;33(2):98-104. doi: 10.1055/s-0041-1736577.) RESPONSE: Thank you for this important point. We have added an initial subsection in the speech perception results reporting on the two articles that included participants with hearing loss. Given that this scoping review search took place in May 2021, we did not include the article you mentioned, though have made a point of being transparent in the introduction, discussion, and limitations that this review captures the state of a dynamic literature at a particular point in time (in particular on pages 5 & 45). The limitations of the study are clearly stated. The conclusions are coherent with the shown data. The figures are clear and easily understandable. Minor points: Line 440: What do you mean with Fivexx? I believe this is a typing mistake. If so, please correct it. Otherwise, the phrase needs clarification. RESPONSE: This was an artefact of our editing process. We have since reviewed and removed these instances throughout. Lines 590-593: The repeated “xx” are probably typing mistakes, that need to be fixed. RESPONSE: These have been removed. Thank you for bringing them to our attention. In summary, given the large and heterogeneous field of investigation and the effective synthesis provided, I commend the authors for their great efforts in this study. The article is easily readable and written in comprehensible English. Once fixed the abovementioned small issues, I consider the work worthwhile to be published. RESPONSE: Thank you for this feedback! Reviewer #2: The authors present a literature review on the acoustic and perceptual effects of face masks on speech. It does a good job summarizing the key results for researchers who are new to the topic, though I would have liked to see more analysis of the conflicting results in the literature. For example, is there a pattern of methodological differences between studies that did or did not find significant impacts on speech intelligibility? RESPONSE: Given that this is a scoping, rather than systematic review, a detailed synthesis of this nature is beyond the purpose of this review. However, we agree with your point that this is important information to consider. We have added information about the presence of noise and some speculation in our final subsection of the perceptual results (page 33). I would also appreciate more analysis of the studies' methodology overall (microphone placement, live talkers vs. mannequins, live listening vs. recordings, how to control for audio/visual variables, how to report attenuation data), since in this new research area there are not yet established best practices. Notably, many of the studies were conducted during lockdown conditions and had to conduct human-subjects experiments remotely. RESPONSE: Again, given the nature of a scoping review, we believe this level of synthesis is not necessarily appropriate or warranted. For this reason, we include the methodological details in the supplemental materials. We now also include an explicit mention of this type of limitation on page 46. Specific comments: - The paper needs some copyediting. There are several "XX" placeholders and one "[CITE]" placeholder. The authors are inconsistent in their formatting of numbers in the text. The usual practice is to write out numbers less than ten, and to never start a sentence with a numeral. RESPONSE: These have all been addressed; thank you for bringing these to our attention. - Line 126-134: This paragraph does not seem to fit into the surrounding paragraphs, which have already introduced respirators. The introduction is choppy overall, with some concepts introduced multiple times. RESPONSE: We agree with this comment. We have collapsed the “Role of masks” within this section. We believe this section is more cohesive now. - Line 164: The purported benefits of transparent masks for listeners with hearing loss are controversial, as many of the reviewed articles point out. They can be helpful in some cases but not others, depending on the relative impact on auditory and visual cues for a particular mask and their relative importance for a particular listener. I would word this sentence more carefully. RESPONSE: This sentence has been revised and worded more cautiously and with caveats. - Line 522: As written, it appears that the subject of the verb "dampened" is "attenuation", which is not what the authors intend to convey. RESPONSE: This has been fixed. - In the audio-visual section, it is not clear exactly what is being compared in each study. There are many variables that might be manipulated in such a study: presenting audio-only recordings with/without masks, audio-visual recordings with/without masks, masked audio imposed on unmasked video, unmasked audio on masked video, unmasked recordings processed to simulate masks, etc. It is unclear whether all the studies in this section were measuring the same thing, so please provide more detail. RESPONSE: Thank you for this comment. We have added substantially more detail in this section to make these differences clearer. - In the section on vocal intensity, what exactly is being measured? If intensity is the overall acoustic energy in the signal, we would not expect most masks to have a measurable effect. Most energy in speech is concentrated at low frequencies, where masks are mostly transparent; even if a mask completely blocked all high frequencies, that would barely change the total energy. Human talkers might increase their effort while wearing a mask, which would affect the overall intensity, but it is not clear if that is what is being studied by all the papers in this section. RESPONSE: We completely agree with your points, and this is exactly what we sought to characterize and is why we separated this section from attenuation. We have clarified your points in the first and last paragraphs in this subsection and added more detail on our reporting of some of the studies. - Table 3 is difficult to read. It is too cluttered to effectively convey information. Perhaps it needs to be broken up, or at last reformatted. RESPONSE: We have modified this into two tables, one reporting on acoustic outcomes and the other on perceptual outcomes. 6. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files. If you choose “no”, your identity will remain anonymous but your review may still be made public. Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy. Reviewer #1: No Reviewer #2: No [NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.] While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org. Please note that Supporting Information files do not need this step. RESPONSE: Done. Attachments Attachment Submitted filename: sim-scoping_response-to-reviewers_2023-01-31.docx https://doi.org/10.1371/journal.pone.0285009.r002
14 Apr 2023 Decision Letter - Andreas Buechner, Editor Acoustic and perceptual impact of face masks on speech: A scoping review PONE-D-22-09426R1 Dear Dr. Knowles, We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements. Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication. An invoice for payment will follow shortly after the formal acceptance. To ensure an efficient process, please log into Editorial Manager at http://www.editorialmanager.com/pone/, click the 'Update My Information' link at the top of the page, and double check that your user information is up-to-date. If you have any billing related questions, please contact our Author Billing department directly at authorbilling@plos.org. If your institution or institutions have a press office, please notify them about your upcoming paper to help maximize its impact. If they’ll be preparing press materials, please inform our press team as soon as possible -- no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org. Kind regards, Andreas Buechner Academic Editor PLOS ONE Additional Editor Comments (optional): Reviewers' comments: Reviewer's Responses to Questions Comments to the Author 1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation. Reviewer #1: All comments have been addressed Reviewer #2: All comments have been addressed ******** 2. Is the manuscript technically sound, and do the data support the conclusions? The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented. Reviewer #1: Yes Reviewer #2: Yes ****** 3. Has the statistical analysis been performed appropriately and rigorously? Reviewer #1: Yes Reviewer #2: Yes ****** 4. Have the authors made all data underlying the findings in their manuscript fully available? The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified. Reviewer #1: Yes Reviewer #2: Yes ****** 5. Is the manuscript presented in an intelligible fashion and written in standard English? PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here. Reviewer #1: Yes Reviewer #2: Yes ****** 6. Review Comments to the Author Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters) Reviewer #1: (No Response) Reviewer #2: (No Response) ****** 7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files. If you choose “no”, your identity will remain anonymous but your review may still be made public. Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy. Reviewer #1: No Reviewer #2: No ******** https://doi.org/10.1371/journal.pone.0285009.r003
Formally Accepted
12 May 2023 Acceptance Letter - Andreas Buechner, Editor PONE-D-22-09426R1 Acoustic and perceptual impact of face masks on speech: A scoping review Dear Dr. Knowles: I'm pleased to inform you that your manuscript has been deemed suitable for publication in PLOS ONE. Congratulations! Your manuscript is now with our production department. If your institution or institutions have a press office, please let them know about your upcoming paper now to help maximize its impact. If they'll be preparing press materials, please inform our press team within the next 48 hours. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information please contact onepress@plos.org. If we can help with anything else, please email us at plosone@plos.org. Thank you for submitting your work to PLOS ONE and supporting open access. Kind regards, PLOS ONE Editorial Office Staff on behalf of Andreas Buechner Academic Editor PLOS ONE https://doi.org/10.1371/journal.pone.0285009.r004

Open letter on the publication of peer review reports

PLOS recognizes the benefits of transparency in the peer review process. Therefore, we enable the publication of all of the content of peer review and author responses alongside final, published articles. Reviewers remain anonymous, unless they choose to reveal their names.

We encourage other journals to join us in this initiative. We hope that our action inspires the community, including researchers, research funders, and research institutions, to recognize the benefits of published peer review reports for all parts of the research system.

Learn more at ASAPbio .