---
id: fundamental-frequency
title: Fundamental Frequency
---

The fundamental frequency (f<sub>0</sub>) is the lowest frequency of a periodic waveform, measured in Hertz (Hz). It is the greatest common divisor of all the frequency components contained in a signal.[^1]


[^1]: https://en.wikipedia.org/wiki/Fundamental_frequency

## Raw Variables

| Variable      | Description |
| ----------- | ----------- |
| `aco_ff`      | **Fundamental frequency.** Frame-wise fundamental frequency values in Hz.    |

## Derived Variables

| Variable      | Description |
| ----------- | ----------- |
| `aco_ff_mean`      | **Fundamental frequency mean.** Mean of aco_ff across the audio file.     |
| `aco_ff_std`      | **Fundamental frequency standard deviation.** Standard deviation of aco_ff across the audio file.     |