Sound & TextGrid: To FormantPath (burg)...
A command that creates a FormantPath object from one selected Sound and one selected TextGrid. It performs a number of short-term spectral analyses with different parameter settings.
The settings for Time step (s), Maximum number of formants, Window length (s) and Pre-emphasis from (Hz) are exacly as you would use them in the Sound: To Formant (burg)... method. Therefore you can use 0.005 seconds, 5.0 formants, 0.025 seconds, and 50.0 Hz, respectively.
For Middle formant ceiling (Hz), you can use 5500.0 Hz for an average female voice and 5000.0 Hz for an average male voice, in the same way as you would do for the Formant ceiling (Hz) setting in Sound: To Formant (burg).... Instead of performing only one analysis, as in Sound: To Formant (burg)..., we perform multiple analyses, each one with a different value for its ceiling. Each analysis result, which is of type Formant, is stored in the FormantPath object. Therefore, after the analyses are done, the FormantPath object contains a collection of Formant objects.
Ceiling step size (Hz)
defines the increase / decrease in the formant ceiling betweeen two successive analyses.
Number of steps up / down
determines the number of different ceiling frequencies starting from the middle formant ceiling and each time adding one ceiling step size. Suppose we have a middle formant ceiling of 5500 Hz, your choice for the ceiling step size was 250 Hz and you chose for number of steps the default 4. Then the first analysis will be performed with the maximum formant frequency set at the default ceiling of 5500 Hz. The next analysis wil be performed with a ceiling of 5500 + 250 = 5750 Hz, the next with a ceiling of 5750 + 250 = 6000 Hz. The third one with a ceiling of 6000 + 250 = 6250 Hz and the fourth one with 6250+250 = 6500 Hz as a ceiling. Now we step down from the default ceiling. The first down wil have a ceiling of 5500 - 250 = 5250 Hz, the next one will have 5250 - 250 = 5000, the next one 5000 - 250 = 4750 and the last one will 4750 - 250 = 4500 Hz as a ceiling. We end up with a collection of 2 * 4 + 1 = 9 different Formants. This results in nine times performing the Sound: To Formant (burg)... command with Formant ceiling (Hz) values of 4500, 4750, 5000, 5250, 5500, 5750, 6000, 6250 and 6500 Hz, respectively. The 5500 was the middle formant ceiling, the 4 steps up ended with a maximum ceiling of 6500 Hz while the 4 steps down ended with a minimum ceiling of 4500 Hz.
© djmw, May 28, 2020