During speech production, the vocal folds may not close completely. The resulting glottal gap (GG) or incomplete glottal closure has not been systematically studied in terms of GG acoustic and/or perceptual consequences. This paper uses high-speed imaging to investigate the relationship between GG area, source parameters, acoustic measures, and voice quality for 6 subjects. Results showed that the cepstral peak prominence (CPP) and the harmonics-tonoise ratio (HNR) are affected by GG area, indicating the presence of more spectral noise with increasing GG area. Analysis of a glide phonation from breathy to pressed for one female speaker showed that measures H1* - H2* and H1* - A3* were positively correlated with GG area under a steady fundamental frequency (F0). In some phonatory modes, increasing F0 may reduce the amplitude of vocal folds vibration, increase GG area, and produce a lower spectral tilt due to significant aspiration noise, leading to a negative correlation between GG area and the spectral tilt measure H1* - A3* .
Bibliographic reference. Chen, Gang / Kreiman, Jody / Shue, Yen-Liang / Alwan, Abeer (2011): "Acoustic correlates of glottal gaps", In INTERSPEECH-2011, 2673-2676.