## 2 Materials and Methods  
Participants  
Forty-one (41) adult participants were included in the study after signing informed consent. Of these participants, 24 had normal hearing, and 17 used cochlear implants. _Normal hearing participants_--Fourteen women and ten men (48 ears) were included after meeting the following inclusion criteria: (1) normal oncology; (2) air-conduction pure-tone thresholds of 25 dB H.L. or less (across 250 to 8000 Hz, including 3000 Hz and 6000 Hz) and an absence of an air-bone gap (ABG) lower than 10 dB HL at each of the four frequencies--5000, 1000, 2000 and 4000 Hz; (3) normal, standard single-frequency (226 Hz) tympanometry, which was defined by a TPP of \(\pm\)50 daPa and peak compensated static acoustic admittance of 0.3-1.6 mL; (4) broadband ipsilateral acoustic stapedial reflex \(\leq\) 85 dBHL and present acoustic stapedial reflex at 500-2000 Hz (no set levels were required); (5) no significant history of otitis media, as determined through an intake questionnaire--all participants in the normal hearing group did not recall any visits to their family physician for an earache, taking any medication for repeated ear infections, or any surgery or repeated earaches as a child; (6) presence of distortion product otoacoustic emissions (DPOAEs)--the DPOAE pass was set at the minimum absolute amplitude of \(-\)6 dB, with a 6 dB signal-to-noise ratio at 1000, 1500, 2000, 3000, and 4000 Hz at the peak pressure using a Titan Interacoustics system with WBT module. The above inclusion criteria were adopted to rule out conductive involvement for ears with normal hearing thresholds. The mean age of these participants with normal hearing thresholds was 24.15 (\(\pm\)4.68) years, and the range was 18-34 years. _Cochlear implant participants_--Eight women and nine men were included. Nine were implanted in the right ear, six in the left ear, and two had bilateral implants (19 implanted ears and 15 non-implanted ears in total). The study inclusion criteria were: (1) normal endoscopy of both ears, (2) a minimum one-year lapse from implantation to ensure that perioperative inflammatory changes would minimally affect the results, (3) normal inner-ear anatomy per preoperative computer-tomography (CT) scans, (4) no history of prior ear surgeries (excluding CI surgery), chronic otitis media, or other middle-ear pathologies. The mean age of these participants was 55.82 (\(\pm\)20.39) years; the range was 18-85 years. Based on preoperative imaging findings, none of the participants had inner-ear anomalies in either ear, and surgical complications afflicted none. All the participants were operated on by two surgeons ([PERSON]; [PERSON]) at a single medical center. Table 1 details some of the demographic data of the participants with impaired hearing, including current age, gender, the type of the implanted CI, side of implantation, and year of implantation. All participants were implanted with Cochlear(tm) devices via a transmastoid approach and a cochleostomy. Preoperative audiograms of 13 of the 17 participants are depicted in Figure 1. For four of the participants, no preoperative audiograms were available due to missing records. Bone conduction thresholds were not available for all but two CI group participants. They had measurable thresholds in the low-frequency range only (likely due to vibrotactile sensation, as there was no indication of conductive component), but no ABG was present. It should be noted that, in all these audiograms, there were no measurable BC thresholds due to the severity of the loss and instruments' output limitations. Moreover, there was no indication of a conductive component in the CI participants' medical history, surgical reports, or imaging, nor in their clear otoscopy results obtained by the ENT surgeon. Figure 1: Preoperative air conduction audiograms of 13 of 17 study participants of the SNHL groups for whom an audiogram was available.