The basic tone of the human voice is generated in the larynx, which is reinforced by and derives its distinctive features from the resonance of the oral and nasal cavities An inappropriate ratio between oral and nasal resonance results in a more nasal timbre of the voice, which is referred to as nasality (hypernasality). Nasality is often present in hearing-impaired patients, and various studies have shown that hypoacusis, including partial deafness (PD), causes voice disorders as a result of disturbed control over the complex process of voice production. This study describes our investigation of nasality in 20 adult Polish patients with post-lingual partial deafness. The results show that PD patients developed more nasality in their voices when compared with individuals in the control group. Observations made 9 months after cochlear implantation for partial deafness indicated a reduction in nasality, with the changes in acoustic parameters achieving statistical significance. Background/Objectives: This study aimed to assess whether partial deafness (PD) causes changes in nasal resonance in adult patients and whether partial deafness cochlear implantation (PDCI) influences the level of nasality. Methods: Voice samples from 20 patients attending the Institute of Physiology and Pathology of Hearing in Warsaw with partial deafness were analyzed and compared with samples from 20 individuals with normal hearing. Voice samples from the same patients were comparatively analyzed at 9 months after cochlear implantation. The level of nasality was assessed using the FFT (Fast Fourier Transform) for acoustic analysis, as well as subjective description by two experienced medical professionals (a medical doctor and a clinical acoustician). Pearson analysis was then performed to determine the correlations between the objective and subjective assessments. Paired two-sample t-tests for means were conducted for statistical analysis. All patients of the Institute of Physiology and Pathology of Hearing in Warsaw declared their deliberate consent to all necessary diagnostic and therapeutic procedures upon admittance. Results: The results show that post-lingual partial deafness causes nasality in adult patients when measured both objectively (p = 0.0001) and subjectively. The average objective level of nasality was 21 dB (SD 4.5), while the subjective level was an average grade of 1.25. The level of nasality presented a positive correlation with the duration of partial deafness. The assessment performed 9 months after cochlear implantation showed a reduction in nasality, achieving 17 dB (SD 4.2) in the objective measurement (p = 0.0002) and a grade of 0.5 when assessed subjectively. Pearson analysis showed a weak correlation between the objective measurement and subjective assessment (r = 0.2). Conclusions: Post-lingual partial deafness causes nasality in adults in a manner that is positively correlated with the duration of hearing impairment. Partial deafness cochlear implantation reduced nasality after 9 months of observation, as shown both objectively (MDVP) and subjectively (perceptual assessment). However, the correlation between the objective and subjective results is rather weak; therefore, objective acoustic methods (e.g., MDVP) should preferably be used for a more credible assessment, while the subjective method may only serve as a rough and general tool in everyday clinical use.
Myszel et al. (Fri,) studied this question.