Glottal Pulses and Harmonic stacks

The harmonic stacks show funny vertical lines or clicks: are those real?

Answer: The clicks in the harmonic stacks can appear when short time scales are included in the analysis.
In the first image below, the timescale was .5-2ms. The clicks are the glottal pulses, and intervals between the clicks equals the fundamental frequency.

The second image is calculated without the shorter time-scales, using timescales 1.5-2ms. The glottal pulses disappear.