Acoustic assessment of voice signal deformation after partial surgery of the larynx.

Objective: The main objective of the present study was to assess the degree of voice signal impairment among patients who had undergone partial surgery of the larynx due to cancer of this organ. Such on evaluation may be helpful in the selection of the optimal surgical technique for the treatment of tumors displaying a varying degree of local advancement.

Methods: A prospective examination was carried out among 128 patients. Additionally a comparative study of the control group consisting of 36 healthy males was carried out. Acoustic tests were carried out in an echo-free chamber. The temporal changes in the value of acoustic pressure of the uttered text were registered. The 'distance' between the normal speech signal and the pathological voice has been established.

Results: The values of the fundamental frequency increase together with an increase of the range of resection of anatomical structures. The biggest differences in the value of results describing the distance from the standard were observed after hemilaryngectomy. The shortest distance from the acoustic standard was observed after chordectomy. No significant differences in the degree of voice signal impairment among patients who had undergone extended chordectomy and hemilaryngectomy were observed.

Conclusion: The above findings can be of help in arriving at an optimum solution in cases of partial surgery of the larynx. The problem is particularly important in situations where there is the choice between different types of surgery.