# Praat: How does pitch floor affect number of frames?

With reference to the documentation for the ToPitch function, http://www.fon.hum.uva.nl/praat/manual/Sound__To_Pitch___.html

pitch floor will determine the length of the analysis window, and always computes 4 pitch values within one window length.

Assume that I use a timestep of 0.005 and a pitch floor of 50 Hz. Further assume that I am analyzing a 3 second clip. Each analysis window will then be 3/50 = 0.06 seconds long. Since the clip is 3 seconds long, there will be 0.06*3 = 50 analysis windows. Praat then computes 4*50 = 200 pitch values.

Yet I am also using a timestep of 0.005. According to the documentation, this should result in 3/0.005 = 600 pitch values. How do I reconcile these two results?

In addition, when I actually analyze the file in Praat, I observe that there are 589 frames. Lowering the pitch floor will result in fewer frames, and increasing the pitch floor will result in the number of frames tending towards 600. By trial and error, the relationship between pitch floor and no. of frames seems to be monotonic but nonlinear. What explains this behaviour?

Thank you.

• Your calculation has non sense. You didn't read well the documentation. You cannot use 50 Hz, the minimum is 75. The first calculation is only given if there is no time step value (ie 0). Then if you choose a time step, so your second calculation is correct. There is no contradiction. Nov 1, 2019 at 6:46
• @amegnunsen Thank you for your response. Could you direct me to the part of the documentation which says that the minimum pitch floor is 75 Hz? In addition, neither the first nor the second calculations are correct in reality. Using a time step of 0.005 secs and a pitch floor of 50 Hz, I obtain 589 frames. I struggle to reconcile this result with the theoretical calculations provided in the documentation. Nov 1, 2019 at 18:30