On the use of the derivative of electroglottographic signals for characterization of nonpathological phonation

TLDR

Electroglottography provides noninvasive glottal activity measurements, yet its derivative—though yielding reliable glottal closing instant indicators—has received little attention. The study aims to guide the use of the electroglottographic derivative for phonation analysis. The authors analyze a database of 18 trained singers to identify peaks in the derivative that mark glottal opening and closing, then propose a correlation‑based algorithm to automatically estimate fundamental frequency and open quotient, and compare it to three other electroglottographic methods for open‑quotient measurement. The study finds that while some peaks are doubled or imprecise—indicating uncommon glottal configurations—the proposed algorithm achieves better agreement with glottal‑flow measurements than most threshold‑based methods for sustained sounds.

Abstract

Electroglottography is a common method for providing noninvasive measurements of glottal activity. The derivative of the electroglottographic signal, however, has not attracted much attention, although it yields reliable indicators of glottal closing instants. The purpose of this paper is to provide a guide to the usefulness of this signal. The main features that are to be found in this signal are presented on the basis of an extensive analysis of a database of items sung by 18 trained singers. Glottal opening and closing instants are related to peaks in the signal; the latter can be used to measure glottal parameters such as fundamental frequency and open quotient. In some cases, peaks are doubled or imprecise, which points to special (but by no means uncommon) glottal configurations. A correlation-based algorithm for the automatic measurement of fundamental frequency and open quotient using the derivative of electroglottographic signals is proposed. It is compared to three other electroglottographic-based methods with regard to the measurement of open quotient in inverse-filtered derived glottal flow. It is shown that agreement with the glottal-flow measurements is much better than most threshold-based measurements in the case of sustained sounds.