Glottal area patterns in numerically simulated diplophonia

The presentation explores diplophonia via numerical simulations of glottal vibrations. The aim of the study is to improve the understanding of glottal wall vibration and area waveform patterns of nonmodal phonation as observed via laryngeal highspeed videos. Diplophonia has been described as the simultaneous perception of two pitches during voicing. A broader definition is the vibration of different glottal structures at two different frequencies. Simulations and direct observations suggest that glottal entrance-exit, left-right as well as anterior-posterior frequency asymmetries cause qualitatively distinct glottal pulse patterns. Additional results show that glottal entrance-exit and anterior-posterior phase shifts of single-frequency vibrations may cause double pulsing as well as spectral subharmonics. This suggests that definitions based on pulse counting within glottal metacycles or detecting spectral subharmonics are too broad to enable distinguishing glottal frequency from glottal phase asymmetries.