Intensity and fundamental frequency control in tracheoesophageal voice

Tracheo-oesophageal voice prostheses are currently widely used following total laryngectomy. Data on maximum phonation time and spectrum have been studied by various Authors and are well known. On the contrary, intensity and fundamental frequency control have received little attention. Intensity and fundamental frequency play an important role in the prosodic aspects of speech. Fundamental frequency variations have been studied in tone language speakers, but the ability to voluntarily change intensity and fundamental frequency remain to be fully investigated. Aim of the present study was to analyse the ability of tracheo-oesophageal voice users to change intensity and fundamental frequency. A total of 12 male subjects who underwent total laryngectomy, in whom a tracheo-oesophageal prosthesis had been inserted, were considered. Maximum phonation time was calculated. Each subject was asked to utter an /a/ as loud as possible and an /a/ as soft as possible. Each subject was then asked to utter an /a/ at comfortable pitch and then at an interval of a fifth. Intensity as well as fundamental frequency variations were compared using Wilcoxon signed rank test. Correlation between maximum phonation time and variation in intensity and in fundamental frequency as well as between the two latter variables was calculated using Spearman's rank correlation coefficient. Mean maximum phonation time was 8 (+/- 3.8) sec. Mean energy was 50 (+/- 4.8) dB SPL for soft phonation and 68 (+/- 4.7) dB SPL for loud phonation. The difference observed was statistically significant (p < 0.02). Mean fundamental frequency values were 106 (+/- 14) Hz and 135 (+/- 34) Hz at the interval of a fifth. The difference observed was statistically significant (p < 0.02). Tracheo-oesophageal voice users were able to change intensity and fundamental frequency, but their control was rather poor. Variations in intensity, as well as fundamental frequency, did not show any correlation with maximum phonation time, and were not correlated with each other. In conclusion, the tracheo-oesophageal voice allows small fundamental frequency variations, but their control appears difficult. On the contrary, intensity variations appear larger and control somewhat easier.