Comparison of Cartilage Conduction Hearing Devices Designed by Ear Impression and Computed Tomography

Abstract

The ear molds and shells of hearing devices are generally designed using ear impressions. Computed tomography (CT) can provide information concerning ear structure, which can be utilized in computer-aided design to create hearing devices. This study aimed to compare the differences in hearing devices designed using either ear impressions or CT images. The ear chip of a cartilage conduction (CC) hearing device was designed based on the ear impression and CT images of patients with aural atresia. Three patients with bilateral (n = 1) or unilateral (n = 2) aural atresia participated in this study. The aided thresholds and subjective evaluations were compared. There were no serious problems with the use of either device, and no remarkable differences were observed regarding their respective audiological and subjective benefits. Regarding the subjective patient preferences, the hearing aid with the device designed via CT imaging was better in three ears of two patients, whereas the wearing comfort of the transducer was better for the device designed via the ear impression. The subjective evaluation of appearance varied among the cases. Finally, a device that was designed using CT findings was purchased for one patient. CT images can be utilized in computer-aided design to create CC hearing devices.

Measurement of the Mechanical Impedance of Ear Cartilage and Development of a Coupler for Vibrator Evaluation of Cartilage Conduction Hearing Aids

“…The mechanical impedance is described in level notation (ref. 1 Ns/m) as in a study by Flottorp et al [13], in which the mechanical impedance of the mastoid and forehead was measured. The variability of the measured mechanical impedance was small, below about 2000 Hz, but significantly above about 2000 Hz.…”

“…CCHAs have been developed for patients suffering from external auditory canal atresia and have demonstrated effectiveness and advantages in clinical studies [5][6][7]. In Japan, the product has been commercially available since 2017 and several medical institutions have published various reports on it [8][9][10][11][12][13]. Furthermore, in recent years, the applicability of CCHAs to patients diagnosed with various hearing impairments has also been under consideration [14].…”

“…Japan, the product has been commercially available since 2017 and several medi tutions have published various reports on it [8][9][10][11][12][13]. Furthermore, in recent years plicability of CCHAs to patients diagnosed with various hearing impairments been under consideration [14].…”

Cartilage Conduction Hearing Aids in Clinical Practice

“…The ear chips are custom fitted, made based on ear impressions. Instead of taking an impression of the ear, computed tomography (CT) images can also be utilized for designing the vibrator [ 20 ]. Compared to the conventional process, the merits of the design using CT images are as follows: no risks related to taking the ear impression, advantage of understanding the shape of the ear in 3D, no physical transport or shipment of an ear impression, and CT images can be sent instantly via the internet.…”

“…If a CT scan is performed for diagnosis or other purposes, the images can be used without additional risk. A previous study reported that the performance of a CT-based vibrator is not significantly inferior to that of an impression-based vibrator [ 20 ]. In contrast, the simple type is available for all ear conditions and can be prepared in advance; patients can try it quickly and unnecessary ear chip costs are also reduced.…”