In speech, vocal folds re-adduct immediately after maximum glottal opening is reached. Peak glottal opening achieved is much larger than for unaspirated stop. Peak glottal opening about the same size as during voiceless aspirated stop. Probably involves medial compression. Stiffening Korean contrasts 3 stops, all voiceless.
Vocal folds are too stiff to vibrate.
Action of crico-thyroid muscles Pitch Lowering Decrease in vertical tension produced by lowering entire larynx.