> ## Documentation Index
> Fetch the complete documentation index at: https://docs.medera.info/llms.txt
> Use this file to discover all available pages before exploring further.

# Fundamental Frequency

> F0 statistics from Praat autocorrelation

F0 is extracted by `_extract_f0_features(sound, audio)` using Praat's autocorrelation method via speech analysis library. | Feature | Unit |
\| :--- | :--- |
\| `f0_mean` | Hz |
\| `f0_std` | Hz |
\| `f0_min`, `f0_max`, `f0_range` | Hz |
\| `f0_confidence` | 0–1 | Gender-aware range:

* Male: 85–180 Hz
* Female: 165–255 Hz
* Auto: 75–300 Hz Reduced `f0_range` correlates with prosodic flatness — a documented marker in major depressive disorder.