1. Breathy Voice
Note that you can hear both a buzzy (periodic) component and a hissy (aperiodic) component.

2. Glottal Source Air flow
Air flow pattern for breathy voice more rounded; i.e., more like a sinusoid.
Glottal Source Air flow
Because of this more sinusoidal flow signal, the spectrum shows a stronger first harmonic than modal.
The more ragged spectrum in the higher freqs (less harmonic regularity) is due to turbulence associated with air escaping thru the glottal chink. This is called aspiration.
From Klatt, D.H. & Klatt, L.C. (1990) Analysis, synthesis, and perception of voice quality variations among female and male talkers. J. Acoust. Soc. Am., 87,

3. Clear (non-breathy) Phonation
Note: Points 1 & 2 are different ways to say the same thing.
Highly periodic time waveform
Extremely well defined harmonics (i.e., nearly all energy is at multiples of f0)
Weak H1 (explanation later)

4. Moderately Breathy Phonation
Less periodic time waveform
Well defined harmonics only in the low frequencies (same as #1 but in freq domain)
Much stronger H1 (explanation later)

5. Very Breathy Phonation
Even less periodic time waveform
Well defined harmonics only in the low frequencies
Very strong H1 (explanation later)

6. mixed periodic & aperiodic
One of the central ideas here is that the larynx is capable of producing a full continuum of vocal qualities, with highly periodic, clear phonation (all buzz) at one end and aperiodic whisper (all hiss) at the other end – and everything in between (breathy voice).
clear phonation
whisper
breathy voice
periodic (buzz)
mixed periodic & aperiodic
aperiodic (hiss)

7. Source-filter Theory Model for Phonated Speech
There’s nothing new here – this is the same model (and the same slide) that we saw earlier.

8. Source-filter Theory Model for Whispered Speech
Vocal tract FRC (more-or-less the same as it would be for phonated speech)
Source spectrum (aspiration)
Output Spectrum
Dense spectrum (i.e., no harmonics)
More energy in the highs than lows
No harmonics anywhere. Why not???