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# Utilities for `FeatureExtractors`

This page lists all the utility functions that can be used by the audio [`FeatureExtractor`] in order to compute special features from a raw audio using common algorithms such as *Short Time Fourier Transform* or *log mel spectrogram*.

Most of those are only useful if you are studying the code of the audio processors in the library.

## Audio Transformations

[[autodoc]] audio_utils.hertz_to_mel

[[autodoc]] audio_utils.mel_to_hertz

[[autodoc]] audio_utils.mel_filter_bank

[[autodoc]] audio_utils.optimal_fft_length

[[autodoc]] audio_utils.window_function

[[autodoc]] audio_utils.spectrogram

[[autodoc]] audio_utils.power_to_db

[[autodoc]] audio_utils.amplitude_to_db