An analysis of spectral details relating to the glottal flow waveform and its first derivative can be used to inform both formant and parametric synthesis strategies. Specifically, the current study presents a conceptual basis for the empirically known relationship between the difference in amplitude between the first and second harmonics (H1-H2) and open quotient (OQ). The position of the first spectral null and the pattern of spectral zeros are shown to contain information relevant to the duration of the open period. The analysis suggests conditions for optimum power output for specific pulse characteristics. These conditions may be important for improved naturalness of the resulting synthesized waveforms and may also be relevant to vocal performance issues.