[Definition of a new temporal voice onset measurement].

The aim of this study was to define a new temporal measurement of voice onset. If in fact it has been established that voice onset contains perceptive information which the listening panel uses to evaluate dysphonia, up till now there has been no objective measurement of this. In order to be able to use instrumental measurement of voice onset, it was first necessary to arrivee at a definition of the limits of onset and end. In electronics, the method of "10%-90%" is used to calculate the rise time (onset) of any signal. It is possible to apply this method to the voice signal using the intensity curve. We have made such measurements on 240 examples of the sustained lal sound produced by 60 dysphonic subjects and 20 normals. The results have shown that measurement of the duration of onset was in the main relevant for the mild (G1) and moderate (G2) dysphonias. We have concluded that the "10%-90%" method allows definition of the contours of onset, and measurement of its duration in a reproducible and standardised way.