This page from Praat may help make this clearer. The basic idea behind analysis of the glottal source is that the source is "caused" by glottal airflow (which is determined by glottal opening). Bandwidth is one of the things that you can get in Praat from LPC formant analysis. A narrow bandwidth concentrates most of the energy at that frequency, and a broad bandwidth ![]() Those resonances (formants) are not precise-frequency "all or nothing" filters, they have a bandwidth where intensity is highest at the resonance frequency, and is a bit lower a bit away from that frequency etc. The value of the first peak in Hz is the fundamental frequency. In the spectrum window, you’ll see several peaks. Then go to the Spectrum menu up top and select view spectral slice. Vocal tract resonances also affect measured amplitude of harmonics. To Find the f0 in Praat: There are several ways to find the fundamental frequency: Highlight the vowel. The point is that if the upper harmonics are low amplitude compared to the fundamental, this points to the glottal source. It is feasible to automate the creation of speech stimuli that vary by voice onset time (VOT) using natural speech, with a praat script and modest background knowledge of covarying acoustic cues such as voice pitch (F0), first-formant (F1) transition, and aspiration intensity. There is an extensive literature from UCLA looking at how to quantify breathiness: measures have included F0-H2, F0-F1 and H0-F2. One problem that has to be controlled is the interaction between phonation and formants: you need to look at vowels where H2 is further from a formant peak (so, not a high vowel). The intensity difference H2-F0 would be in the direction of a large negative number for breathy, and in the direction of a positive number for creaky. Therefore one classic acoustic diagnosis of phonatory difference is to compare harmonic intensity, for example comparing the first two harmonics. At the creaky end of the continuum, energy falls off more gradually. At the breathy end of the phonatory continuum, most of the acoustic energy is in the fundamental, so H0 is high and subsequent harmonics fall off rapidly. ![]() The overall production picture is that with creaky voicing, the vocal folds remain in contact for the longest time and with breathy voice, they are in contact the shortest time. There are various languages (Hmong-Mien, Western Nilotic, Otomanguean, San) with distinctive breathiness and creakiness associated with vowel. ![]() The second pertains to the shape of the glottal source wave, and people studying linguistic phonation types focus on that. One factor influencing intensity is subglottal pressure, which is immaterial at the segmental level (you can say a word or phrase loudly that way, but you can't limit the increased loudness to a phoneme).
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