Acoustic measure of noise energy in vocal folds operated patients

Voiced sounds are the result of a periodic excitation of the vocal tract due to the vocal folds vibration. They are characterised by the fundamental frequency of the phonation, named pitch, which is the rate of vibration of the folds. In pathologic voices, pitch variations are indicative of the patient status, hence robust pitch estimation methods are required in order to track such variations and to quantify the degree of voice deterioration. This paper compares some pitch estimation methods, with modifications suitable for the present application. A measure of the signal "noise" level is adopted which allows tracking its variations with time. The methods are tested on simulated signals and then applied to real signals coming both from healthy and pathologic voices.