In order to evaluate the vocal quality of tracheo-oesophageal and oesophageal speech, several objective acoustic parameters were measured in the acoustic waveform (fundamental frequency, waveform perturbation) and in the frequency spectrum (harmonic prominence, spectral slope). Twelve patients using tracheo-oesophageal speech (with the Provox valve) and 12 patients using oesophageal speech for at least two months, participated. The main results were that tracheo-oesophageal voices more often showed a detectable fundamental frequency, and that this fundamental frequency was fairly stable; there was also a tendency to more clearly defined harmonics in tracheo-oesophageal speech. This suggests a more regular vibratory pattern in the pharyngo-oesophageal segment, due to the more efficient respiratory drive in tracheo-oesophageal speech. So, a better quality of the voice can be expected, in addition to the longer phonation time and higher maximal intensity.