## 4 Discussion
Only frequencies where the differences between conditions were statistically significant are shown in the table (MANOVA). increase middle-ear cleft volume and absorbance [39; 40]. Cochleostomy might serve as a third window and affect absorbance, and the stiffness. Another possible explanation was proposed by [PERSON] et al. [41], who suggested that bone dust produced during mastoid drilling can increase ossicular mass. An increase in stiffness of the middle-ear system in cases of otosclerosis and negative middle-ear pressure has also been shown to be associated with a decrease in absorbance at lower frequencies [42; 43; 44]. Over time, cochlear implantation can also incite temporal bone fibrosis and ossification, affecting mass stiffness, especially at the basal turn of the cochlea [45; 46]. In a recent paper, [PERSON] et al. [47] studied the impacts of WBT in normal ears of fat sand rats before and after each stage of superior canal dehiscence (SSCD) surgery, including a bullotomy, creation of SSCD, and after patching. Opening of the bulla and creation of SSCD were associated with a remarkable increase in absorbance at low frequencies, a large decrease frequency around 1800 Hz, and changes in absorbance at high frequencies. Patching the SSCD reversed the absorbance changes at the resonance frequency and at high frequencies but not at the low frequencies. All these changes were related to the alterations that occurred in the stiffness and cochlear impedance of the middle and inner ear. [PERSON] et al. [29] have also shown that the power absorbance in human participants with confirmed SSCD can be used to effectively screen for this condition. The secondary aim of this study was to explore the possible effect of SNHL on WBT results. Ears with severe to profound SNHL without CI showed a decrease in absorbance at high frequencies (4000 and 5000 Hz) as compared to ears with normal hearing. It is unclear what mechanisms may contribute to WBT changes around 4000 Hz in individuals with SNHL. SNHL is associated with structural and mechanical changes in the Organ of Corti. These changes may include loss or atrophy of cochlear neurons and sensory cells; labyrinthine fibrosis, especially of the stria vascularis [16; 17; 19]; and abnormal, or even absence of the, tectorial membrane [18]; such changes are more common at the cochlear base [15; 42; 43; 48]. Furthermore, noise-induced SNHL revealed changes in the cochlear partition micromechanics, which were attributed to a reduction in stiffness [49; 50]. Another confounding factor that may have affected the current WBT results was the age of the hearing-impaired subjects as compared to the participants with normal hearing. As found in previous reports, implanted and non-implanted adults showed a decrease in absorbance at high frequencies (4000-5000 Hz) compared to young subjects with normal hearing [36; 37]. This reduction in high frequencies was not found in the comparison of young implanted and young normal-hearing participants [38]. The bulk of the anatomical research on the aging of the middle ear indicates an increase in middle-ear mas and stiffness, affecting the absorbance at both low and high frequencies [51; 52; 53; 54; 55; 56]. In general, most studies associated aging with a decreased absorbance at high frequencies, although age groups that were most affected varied between studies. On the other hand, [PERSON] et al. [57] compared middle-aged otosclerosis patients with young subjects with normal hearing and demonstrated an increase in absorbance at high frequencies. This may suggest that middle-ear mechanics overweighs changes associated with aging. Thus, the changes in the absorbance at high frequencies might be related to age, the presence of the CI in the inner ear, the CI surgery, and the existence of SNHL. Further studies are required to elucidate the effect of each factor and its synergic impacts on WBT. Standard 226 Hz probe tone tympanometry results were normal (type A) for most participants and were not differentiated between the three study groups.