I'm doing an acoustic-phonetic analysis of read-speech in an American English corpus. If we want to set a window/frame size (25 - 30 ms) to cover the majority of vowels in the corpus, but some vowels (in rapid speech) are smaller in duration -- then does Praat automatically adjust to one-frame only in such cases? I don't want to lose them, because data is sparse anyway.
Praat doesn't automatically adjust, or have any idea about vowels versus consonants. Also, the window size is set by the individual analysis, so there isn't a one-size universal window. I can't think of a context where a window size as big as 25 msc would be correct. I think your question is, what does Praat do if the duration is the selection is too short, given the requested analysis. The manual on Sound: To Spectrogram is somewhat informative
For purposes of computation speed, Praat may decide to change the time step and the frequency step. This is because the time step never needs to be smaller than 1/(8√π) of the window length, and the frequency step never needs to be smaller than (√π)/8 of the inverse of the window length. For instance, if the window length is 29 ms, the actual time step will be never be less than 29/(8√π) = 2.045 ms. And if the window length is 5 ms, the actual frequency step will never be less than (√π)/8/0.005 = 44.31 Hz.
It seems you have to read the details of the particular analysis to see how Praat deals with hyper-short windows.