Cartilage Conduction Hearing Aids in Clinical Practice
Round 1
Reviewer 1 Report
This review article summarises the current understanding of cartilage conduction hearing aids in clinical practice. The authors invented the system and should be praised for developing the clinically-available new hearing aids.
One point from this reviewer: as correctly argued, the cartilage conduction hearing aids are beneficial for bilateral aural atresia, especially for sound localization, but how about the effect for sound localization of unilateral aural atresia patients? If there is any study that investigated the point, please include the study in this review.
Author Response
One point from this reviewer: as correctly argued, the cartilage conduction hearing aids are beneficial for bilateral aural atresia, especially for sound localization, but how about the effect for sound localization of unilateral aural atresia patients? If there is any study that investigated the point, please include the study in this review.
=> Thank you for your valuable suggestion. Although we were able to retrieve one paper reporting sound localization in unilateral aural atresia, the number of cases was not sufficiently large to reach a conclusion. Therefore, we have added the following sentences in the revised manuscript (Lines 353–358).
“Kitama et al. measured sound localization in patients with unilateral atretic ears using CC hearing aid, BAHA, and ADHEAR on the atretic ear. Compared with the un-aided condition, no significant improvement was observed in any of the three aided conditions [28]. However, the comparison was provided for only one patient. Thus, a firm conclusion could not be drawn regarding the effect of CC hearing aid on sound localization in patients with unilateral atretic ears.”
Reviewer 2 Report
The authors conducted a comprehensive review on cartilage conduction hearing aids.
It seems that in the context, it refers to an ear with a normal pinna (outer ear) and middle ear structure. I'm curious about what the term 'open ear' specifically denotes.
I believe that cartilage conduction hearing aids would result in more loss of sound energy compared to bone conduction. I'm curious if there are any issues related to discomfort or sensation caused by vibration of sound transducer.
I am interested in whether there are any displacements in the position of the transducer or any potential disruptions in sound transmission caused by vibrations of transducer. .
None
Author Response
The authors conducted a comprehensive review on cartilage conduction hearing aids.
It seems that in the context, it refers to an ear with a normal pinna (outer ear) and middle ear structure. I'm curious about what the term 'open ear' specifically denotes.
=> Thank you for your valuable suggestion. The term ‘open ear’ had been used in the manuscript as this term was used in the previous study. However, as the Reviewer rightly pointed out, the use of the term ‘open ear’ may be confusing. Therefore, we have replaced it with the term ‘canal-open ear’ throughout the manuscript to avoid misinterpretation.
I believe that cartilage conduction hearing aids would result in more loss of sound energy compared to bone conduction. I'm curious if there are any issues related to discomfort or sensation caused by vibration of sound transducer.
I am interested in whether there are any displacements in the position of the transducer or any potential disruptions in sound transmission caused by vibrations of transducer.
=> Thank you for your questions. In canal-open ears, a relatively loud sound can be heard clearly when the transducer is placed on the aural cartilage, particularly on the tragus, compared with the mastoid. The signal transmission pathway should include the skull bone for conduction in a bony atretic ear. Thus, the energy loss may become large as mentioned by the Reviewer. However, our previous study demonstrated that the thresholds in the cartilage stimulation condition were not inferior to those in the bone stimulation condition. The explanation of the signal transmission in the atretic ear is included in section 6.
As no previous study has reported objective evidence of disruption in sound transmission, we cannot objectively mention it in the manuscript. However, the patients who use CC hearing aids have not reported it in clinical practices, and good speech recognition is usually obtained in the aided condition. Thus, we believe that it does not influence CC hearing aid use.
Reviewer 3 Report
The authors in an interesting way describe the clinical possibilities of using cartilage conduction devices, their history, and results of work. Well written, interesting work. Minor corrections needed.
Line 143: Is there a dedicated, special method for fitting CC hearing aids?
Line 250: The authors write: „77% (110 dB signal to noise ratio [SNR]), and 52% (15 dB SNR).” SNR 110 dB is impossible. I suppose it is 10 dB SNR. If so, how do the authors explain why the result at 15 dB SNR is worse than at 10 dB SNR? This could be mistake, I suggest checking with the source.
Author Response
=> Thank you for valuable your suggestion. In accordance with your suggestion, we have inserted a brief explanation regarding CC hearing aid fitting in the revised manuscript (Lines 144–148).
“Linear amplification is utilized in patients with conduction hearing loss, such as those with aural atresia. The fitting software depicts the frequency responses on the screen; however, these simulated gains are not always equal to the actual values. Therefore, the real gains must be confirmed by measuring the unaided and aided thresholds.”
Line 250: The authors write: „77% (110 dB signal to noise ratio [SNR]), and 52% (15 dB SNR).” SNR 110 dB is impossible. I suppose it is 10 dB SNR. If so, how do the authors explain why the result at 15 dB SNR is worse than at 10 dB SNR? This could be mistake, I suggest checking with the source.
=> Thank you for bringing this error to our notice. We sincerely apologize for this oversight. Please note that we have corrected the sentence as shown below (Lines 267–270):
The mean AzBio scores were 90% (quiet), 77% (+10 dB signal to noise ratio [SNR]), and 52% (+5 dB SNR) when isolating the BC device ear, and 90%, 73%, and 41% when isolating the CC hearing aid ear.
