Time and Frequency Feathering

Processing that stops abruptly at the edge of a spectral selection can leave an audible seam, especially when the selection covers a narrow frequency band or a very short moment in time. Feathering fades the processing in and out across the border of the selection instead, so that the processed and the unprocessed audio blend into each other.

Feathering is a property of the selection itself, not of an individual processor. Whatever you apply to a feathered selection — an Enhancement tool, an effect, or a cut, copy or paste operation — follows the same fade.

Adding Feathering to a Selection

Make a selection in the spectral editing mode. The feathering handles appear around the selection.

In addition to the four corner handles that resize the selection, a handle appears at the middle of each edge of the selection:

• The handles at the left and right edges control the feathering in time. These handles are labeled with a T in the above image.

• The handles at the top and bottom edges control the feathering in frequency. These handles are labeled with a F in the above image.

Click one of these edge handles and keep the mouse button down while dragging away from the selection. The further you drag, the longer the fade. Drag back towards the selection to reduce the feathering, and all the way back to remove it.

The feathered area is drawn as a subtle gradient around the selection, so you can see how far the processing reaches beyond the selected region. The below image shows the gradient with feathering applied to both time and frequency.

Choosing the Amount

There is no single correct setting, but two rules of thumb help:

• Feather in time when the material is tonal and the selection is short. A fade of a few tens of milliseconds is usually enough to avoid a click at each end of the processed region.

• Feather in frequency when the selection covers a narrow band inside a broadband sound. Without frequency feathering, the processed band can stand out as a hole in the spectrum.

Keep the feathering as small as it can be while the transition remains inaudible. Excessive feathering pulls wanted audio into the processed region and reduces the amount of noise actually removed.

Feathering and Editing

Feathering also applies when you cut, copy or paste a spectral selection. The audio is faded in and out across the feathered border rather than being removed or inserted with a hard edge, which is what makes it possible to lift a sound out of a spectrogram without leaving a rectangular gap behind.