# Electroglottographic Analysis of the Voice in Young Male Role of Kunqu Opera
### EGG Analysis  
Electroglottography is a non-invasive technique to measure variations in the contact area between the two vocal folds as a function of time. It is related complementarily to the glottal air flow [9]. The peaks in the derivative of the EGG signal correspond to the closing and opening events of the vocal folds [10; 11; 12]. A model [9] that pinpoints certain landmarks and their relation to the glottal airflow pulse during normal voicing is widely used to speculate the movement and position of the vocal folds during phonation [12]. Clinically meaningful alterations of vocal fold status and behavior also have been reported to result in different geometric characteristics in the EGG waveform [13]. Different phonation settings result in different phonation types and characteristic EGG shapes [4; 14; 15]. The production of modal voice is carried out with moderate adductive tension, medial compression, and longitudinal tension in the lower pitch range of a speaker. In a considerably higher pitch range, when the mass of the vocal fold is made stiff and less mobile, which often is accompanied by slightly abducted folds, a falsetto is produced. Unlike modal voice and falsetto, breathiness is a modificatory setting of vocal folds. The notion of breathy voice involves a type of phonation which can be produced over a very wide range of air flows [4].  
Three EGG parameters, namely, fundamental frequency (\(f_{o}\)), contact quotient (CQ), and speed quotient (SQ), have been found to be associated with phonation types [2; 5; 16]. The CQ is defined as the ratio between the contact phase of the EGG signal and the fundamental period, as can be seen in Figure 1. The CQ and the closed quotient derived from the glottal flow are not necessarily equal, since transglottal airflow may occur during incomplete glottal closure [17]. For EGG waveforms with a single peak, a high CQ is typically related to a pressed voice, while a low one is commonly observed for breathy voice. However, this is not true for a double-peak EGG signal. The SQ was originally defined for glottal flow as the duration of the opening phase divided by the duration of the closing phase [18]. A high SQ corresponds to faster glottal contact and indicates that the voice has more high-frequency energy [19]. For EGG, the SQ is the ratio between the decontacting phase and the contacting phase (see Figure 1) in the EGG [5]. The SQ is related to the convergence (along with vertical phasing) in the glottis [20] and the degree of tension of vocal fold; the greater the tension (such as falsetto) is, the closer to 100% the SQ will be. In several Chinese dialects and minority languages, compared with modal voice, the special vocal fry showed a lower \(f_{o}\), smaller CQ, and larger SQ; the breathy voice showed a lower \(f_{o}\), smaller CQ, and smaller SQ; the pressed voice showed a lower \(f_{o}\), larger CQ, and larger SQ; and the high-pitched voice showed a higher \(f_{o}\), larger CQ, and smaller SQ [5]. In order to correctly calculate the EGG parameters, three methods have been previously applied in research to pinpoint the moments of glottal contact and of loss of glottal contact [21; 22; 23; 24; 25]. The criterion-level method [23] showed better applicability for double-peak EGG signals [14], weak signals with a large high-frequency noise component, and other special cases, and was more appropriate for the analysis of the complex EGG signals of YMs.