The aim of this study is to develop mathematical 3D finite element (FE) models for numerical simulations of vibroacoustic properties of the human vocal tract after a tonsillectomy. Similar experimental studies are not easily realizable on living subjects. The FE models of the acoustic spaces corresponding to the human vocal tract for the Czech vowels /a:/ and /i:/ and the acoustic space around the human head were used in numerical simulations of phonation. The acoustic resonant characteristics of the FE models were studied using modal and transient analyses (excitation by a short pulse). Calculated results show that a tonsillectomy causes a frequency shift of the 3rd (down by approximately 180 Hz) and 4th (down by approximately 120 Hz) formants down to the lower frequencies for the vowel /a:/ and similarly for the 2nd, 4th and 5th formants for the vowel /i:/ (all down by approximately 100 Hz). Similar effects and results can be found in experimental studies in literature. The formant changes are dependent on the size of additional acoustic spaces that occur after a tonsillectomy. The verification of the model was performed on the recordings of patients before and after the tonsillectomy operation. Multi-Dimensional Voice Program (MDVP Advanced, KAY Elemetrics Corp.) was used for the comparing of the formant centre frequencies. Very small differences in the results of subjective evaluation of the voice before and after tonsillectomy were found.
Skull base tumors and, in particular, vestibular schwannoma (VS) are among the etiological reasons for single-sided deafness (SSD). Patients with SSD have problems in understanding speech in a noisy environment and cannot localize the direction of sounds. For the majority, this is the handicap for which they try to find a solution. Apart from CROS hearing aids, Baha is one of the most frequently used systems for SSD compensation. 38 patients with single-sided deafness after retrosigmoid removal of a vestibular schwannoma underwent testing with a Baha softband from September 2010 to August 2014. Sixteen patients (42 %) finally decided to accept Baha implantation. Subjective experience with the Baha softband was evaluated by patients using the BBSS questionnaire immediately after testing. Objective evaluation of the effect was performed as a measurement of the sentence discrimination score in noise and side horizontal discrimination without a Baha and 6 weeks and 12 months after a sound processor fitting. There was a significant improvement in sentence discrimination in the 6 week (64.0 %) and 1 year (74.6 %) interval of follow-up in comparison with understanding without Baha (24.0 %, p = 0.001) in situations when sentences are coming from the side of the non-hearing ear and noise contralaterally with SNR -5 dB. Baha can significantly improve sentence discrimination in complex-listening situation in patients with SSD after the VS surgery.
Skull base tumors and, in particular, vestibular schwannoma (VS) are among the etiological reasons for single-sided deafness (SSD). Patients with SSD have problems in understanding speech in a noisy environment and cannot localize the direction of sounds. Baha is one of the most frequently used systems for SSD compensation. Out of 38 patients with SSD after retrosigmoid removal of VS who underwent testing with Baha softband, 16 were satisfied and were indicated for Baha implantation. Two surgical approaches have been used-the Nijmegen linear incision technique with subdermal thinning (Group I, implant BI300) and fast surgery technique without subdermal thinning (Group II, implant BIA400). The duration of the surgery, the implant stability measured by Ostell, and skin or soft tissue reactions in long range follow-up were evaluated and compared between Group I and II. There was a difference in duration of surgery, in Group II procedures averaged significantly faster (p > 0.001). In both groups, there was a similar trend of the gradual increase of implant stability. In the Group I and II, there was comparable rate of the skin or soft tissue reactions grade 0, I, II, or III. We have proved Baha to be a suitable possibility for SSD patients after the removal of VS, regardless of the approach. After the retrosigmoid approach to the VS, the key step of Baha implantation must be to reach intact healthy bone to avoid implantation into scar tissue.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.