A Journey to Hear: The Evolution of Cochlear Implants

Round 1

Reviewer 1 Report

This manuscript reviews the development and evolution of cochlear implants (CI).  The topic is of central importance for otolaryngology and audiology, and the manuscript covers a broad range of topics that will be of interest to those practitioners.  My general comments concern the way the manuscript is written; the tone seems a bit too enthusiastic for an academic paper.  The value of CIs as an intervention to treat hearing loss in not in dispute, but the first sentence is as good an example as any of the excess of superlatives: CIs are "a groundbreaking milestone in auditory rehabilitation, presenting a transformative solution".   Another example occurs a few sentences later: "This technological marvel significantly transcends its initial purpose, becoming a source of hope that substantially improves the overall quality of life for those contending with profound hearing challenges".  In contrast, the manuscript gives little or no attention to less-positive news. For example, here is a quote from a recent review paper by different authors:  "For many CI users, speech communication remains challenging and effortful, particularly in everyday, real-world listening conditions" (Tamati et al, Annual Review of Linguistics, https://doi.org/10.1146/annurev-linguistics-031220-011554).  The present manuscript does a poor job of acknowledging that reality, and that diminishes its value, especially for the non-experts who may be most likely consult an encyclopedia entry.  Another concern is that the level of the presentation is uneven.  Some marginally-relevant historical facts are presented in great detail (in particular in section 2 and the beginning of section 3), while more recent and more important information is presented at a superficial level; signal processing strategies, for example, are a crucial component of CI design but are mentioned only briefly.  The review tends to present conclusions without mentioning the evidence that led to those conclusions.  An audience of professionals should expect more. 

Specific comments:

line 21:  It is an odd choice to list one individual's name as a keyword, when many have made equally-important contributions 

lines 36-37:  "electrode", singular, is not accurate; all modern devices have a multi-electrode array

line 150:  my copy of the manuscript did not include a figure

line 210-211, "the digitized sound is filtered through a bank of electrodes corresponding to intracochlear electrodes".  The phrase "bank of electrodes" was probably supposed to be "bank of filters"

lines 235-240:  These two sentences make strong claims that should be supported by references to published research.

line 241, paragraph 5.2:  This is another example of an overly-positive description of a subfield of CI research for which many issues have yet to be resolved. 

line 263, "Advancements in signal processing algorithms ...":  This statement would be strengthened if the algorithms were described.

line 280-281, "Others [in the Deaf community] approach them cautiously, expressing concerns about cultural assimilation and the potential threat to deaf culture and sign language":  This statement is correct, but many would say it understates the level of concern.  Although the attitudes and concerns of the Deaf community have been widely discussed, the single cited paper is one written by an undergraduate for what appears to be a non-peer reviewed magazine published by a regional professional society.  This is another example of lack of perspective about what is good and what is less good about CIs.

lines 283-284, sentence that starts "While some embrace ..." more or less repeats what has already been said in the previous paragraph.

Author Response

Reviewer 1 General Comment:

This manuscript reviews the development and evolution of cochlear implants (CI).  The topic is of central importance for otolaryngology and audiology, and the manuscript covers a broad range of topics that will be of interest to those practitioners.  My general comments concern the way the manuscript is written; the tone seems a bit too enthusiastic for an academic paper.  The value of CIs as an intervention to treat hearing loss in not in dispute, but the first sentence is as good an example as any of the excess of superlatives: CIs are "a groundbreaking milestone in auditory rehabilitation, presenting a transformative solution".   Another example occurs a few sentences later: "This technological marvel significantly transcends its initial purpose, becoming a source of hope that substantially improves the overall quality of life for those contending with profound hearing challenges".  In contrast, the manuscript gives little or no attention to less-positive news. For example, here is a quote from a recent review paper by different authors:  "For many CI users, speech communication remains challenging and effortful, particularly in everyday, real-world listening conditions" (Tamati et al, Annual Review of Linguistics, https://doi.org/10.1146/annurev-linguistics-031220-011554).  The present manuscript does a poor job of acknowledging that reality, and that diminishes its value, especially for the non-experts who may be most likely consult an encyclopedia entry.  Another concern is that the level of the presentation is uneven.  Some marginally-relevant historical facts are presented in great detail (in particular in section 2 and the beginning of section 3), while more recent and more important information is presented at a superficial level; signal processing strategies, for example, are a crucial component of CI design but are mentioned only briefly.  The review tends to present conclusions without mentioning the evidence that led to those conclusions.  An audience of professionals should expect more. 

Author’s Response: We thank the reviewer for their comments; they helped us improve our manuscript. Although we and many other scientists consider cochlear implants a «medical miracle», and we have witnessed impressive improvements in many children and adults implanted by our team’s surgeon, we have removed some phrases deemed excessive by the reviewer. Additionally, we included the bibliography suggested by the reviewer, as we do not want to be perceived as presenting only the «positive» aspects selectively. Naturally, each case requiring implantation is unique, and by embarking on this process, you offer the individual, whether a child or an adult, the best possible chances to evolve and develop hearing and skills through dedicated effort, therapies, and a strict program. No one disputes that it is challenging; it requires effort, treatments, and a rigorous schedule for the person. Indeed, very recently, we happened to visit the «Science Museum» in London, where cochlear implants were prominently featured among the devices that literally can change lives with the help of technology and science.

Specific comments:

Reviewer Comment 1: line 21:  It is an odd choice to list one individual's name as a keyword, when many have made equally-important contributions 

Author’s Response: We agree with the reviewer and we have removed this specific keyword.

Reviewer Comment 2: lines 36-37:  "electrode", singular, is not accurate; all modern devices have a multi-electrode array

Author’s Response: We agree with the reviewer and we edited accordingly.

Reviewer Comment 3: line 150:  my copy of the manuscript did not include a figure

Author’s Response: Probably by mistake, the Figure was not attached. The reviewer can find it in the revised version.

Reviewer Comment 4: line 210-211, "the digitized sound is filtered through a bank of electrodes corresponding to intracochlear electrodes".  The phrase "bank of electrodes" was probably supposed to be "bank of filters"

Author’s Response: We agree with the reviewer and we edited accordingly.

Reviewer Comment 5: lines 235-240:  These two sentences make strong claims that should be supported by references to published research.

Author’s Response: We agree with the reviewer and we have added references.

Reviewer Comment 6: line 241, paragraph 5.2:  This is another example of an overly-positive description of a subfield of CI research for which many issues have yet to be resolved. 

Author’s Response: We agree with the reviewer, we rephrased and added an extra reference, making it clear that there are still challenges to be solved.

Reviewer Comment 7: line 263, "Advancements in signal processing algorithms ...":  This statement would be strengthened if the algorithms were described.

Author’s Response: We agree with the reviewer, but we have decided not to describe the processing algorithms in details. We have modified the text accordingly to make it clear.

Reviewer Comment 8: line 280-281, "Others [in the Deaf community] approach them cautiously, expressing concerns about cultural assimilation and the potential threat to deaf culture and sign language":  This statement is correct, but many would say it understates the level of concern.  Although the attitudes and concerns of the Deaf community have been widely discussed, the single cited paper is one written by an undergraduate for what appears to be a non-peer reviewed magazine published by a regional professional society.  This is another example of lack of perspective about what is good and what is less good about CIs. lines 283-284, sentence that starts "While some embrace ..." more or less repeats what has already been said in the previous paragraph.

Author’s Response: We fully understand what the reviewer means and respect their opinion. We have added an additional reference that clearly address the “dichotomy” within the Deaf community. The first paper we mention is published in a journal included in PubMed, and we believe we can reference it. Please let the Editor decide.

Reviewer 2 Report

This is an interesting article on insight of cochlear implantation.

The historical part of the thesis is spotless and very interesting. The more technical parts are satisfying but maybe too brief, and it would be nice to be expanded a little further, both in text and citations.

Some specific example will follow.

The paragraph on bilateral CI should be expanded further. For istance, it could be interesting to briefly discuss the (many) advantages of a bilateral electrical stimulation, but also the (little) drawbacks. Another aspect to be discuss should be the eventuality of a bilateral sequential CI. Some (but not all) of those aspects can be found here for what concern the pediatric population: Forli F, Bruschini L, Franciosi B, Berrettini S, Lazzerini F. Sequential bilateral cochlear implant: long-term speech perception results in children first implanted at an early age. Eur Arch Otorhinolaryngol. 2023 Mar;280(3):1073-1080. doi: 10.1007/s00405-022-07568-4. Epub 2022 Aug 3. PMID: 35920894; PMCID: PMC9899753.

Stimulation strategies other than CIS, and their extremely advanced recent evolution should be further explored.

Future prospects could be improved further. A comprehensive description of future developments in CI should be found here: Forli F, Lazzerini F, Bruschini L, Danti S, Berrettini S. Recent and future developments in cochlear implant technology: review of the literature. Otorhinolaryngology 2021;71:196-207. DOI: 10.23736/S2724-6302.21.02379-3.

Despite these suggestion, after those minor editing, the article should be considered for publication. 

Author Response

Reviewer 2 General Comment:

This is an interesting article on insight of cochlear implantation. The historical part of the thesis is spotless and very interesting. The more technical parts are satisfying but maybe too brief, and it would be nice to be expanded a little further, both in text and citations.

Author’s Response: We thank the reviewer for their comments; they helped us improve our manuscript.

Some specific examples will follow.

Reviewer Comment 1: The paragraph on bilateral CI should be expanded further. For istance, it could be interesting to briefly discuss the (many) advantages of a bilateral electrical stimulation, but also the (little) drawbacks. Another aspect to be discuss should be the eventuality of a bilateral sequential CI. Some (but not all) of those aspects can be found here for what concern the pediatric population: Forli F, Bruschini L, Franciosi B, Berrettini S, Lazzerini F. Sequential bilateral cochlear implant: long-term speech perception results in children first implanted at an early age. Eur Arch Otorhinolaryngol. 2023 Mar;280(3):1073-1080. doi: 10.1007/s00405-022-07568-4. Epub 2022 Aug 3. PMID: 35920894; PMCID: PMC9899753.

Author’s Response: We agree with the reviewer, we have added additional information, as well as the paper they mentioned.

Reviewer Comment 2: Stimulation strategies other than CIS, and their extremely advanced recent evolution should be further explored. Future prospects could be improved further. A comprehensive description of future developments in CI should be found here: Forli F, Lazzerini F, Bruschini L, Danti S, Berrettini S. Recent and future developments in cochlear implant technology: review of the literature. Otorhinolaryngology 2021;71:196-207. DOI: 10.23736/S2724-6302.21.02379-3. Despite these suggestions, after those minor editing, the article should be considered for publication. 

Author’s Response: We agree with the reviewer, we have added additional information, as well as the paper they mentioned.

Round 2

Reviewer 1 Report

My comments have been addressed.

Reviewer 2 Report

Paper is suitable for publication after minor revision.