---
id: shimmer
title: Shimmer
---

The shimmer of an audio signal is the cycle-to-cycle amplitude variation of the sound wave.[^1]

[^1]: Horii, Y. (1980). Vocal shimmer in sustained phonation. Journal of Speech, Language, and Hearing Research, 23(1), 202-209.

## Raw Variables

| Variable      | Description |
| ----------- | ----------- |
| `aco_shimmer`      | **Shimmer.** Frame-wise measurements of shimmer.    |

## Derived Variables

| Variable      | Description |
| ----------- | ----------- |
| `aco_shimmer_mean`      | **Shimmer mean.** Mean of `aco_shimmer` across the audio file.     |
| `aco_shimmer_std`      | **Shimmer standard deviation.** Standard deviation of `aco_shimmer` across the audio file.     |