Practical Guidelines for Implementing Vocal Tract Resonances Characterization with Excitation at the Lips

International audienceThe measurement of vocal tract resonances is crucial to understand voice acoustics. Their characterization using a broadband excitation signal and pressure measurements both at the lips is a good compromise between accuracy, speed and intrusiveness. In this paper we address some practical guidelines for performing such measurements in order to provide reliable estimates for resonance frequencies and quality factors. We also experiment the possibility to move away microphone from excitation at the lips, with a cylindrical waveguide as ideal vocal tract and its line-transmission model. Using a far-field model in which pressure decreases as the inverse of the distance from excitation at the lips, the microphone could be placed anywhere as soon as the Signal-to-Noise Ratio is good enough: measurements become more sensitive to interferences with other acoustics sources. Modal analysis is performed with a robust method using both amplitude and phase of measured functions. Resonance frequencies and quality factors estimations at distances up to 30 cm deviates by less than 0.2% and 10% respectively from reference measurement at the lips validating accurate characterization with a distant microphone from the lips