TechNote (Archived)

Normalize audio files in Adobe Audition

Normalization is an editing function that adjusts the highest peak of a waveform to a certain percentage relative to the digital maximum - 0dBfs, thereby raising or lowering all other peaks accordingly. This technique is most useful when you author a CD or master a collection of songs and each of your CD tracks varies in overall peak amplitude. Normalizing a collection of tracks applies a consistency that is typical for CDs that will be played on consumer equipment (for example, stand-alone CD or DVD players).

Adobe Audition provides a number of normalization possibilities (for example, Effects > Amplitude > Normalize, Hard Limiting). However, the Group Waveform Normalize command is an easy-to-use, time-saving feature for multiple file normalization. This feature provides a short normalization process that uniformly matches the loudness of your files based on their RMS levels. You can select true RMS normalization or Equal Loudness Contouring, which takes into account the frequencies to which the human ear is sensitive.

To perform basic normalization with the Group Waveform Normalize command:

1. Open a series of files and choose Edit > Group Waveform Normalize. When you are prompted to choose files, press and hold the Ctrl key and then select all the files that you want to normalize.

2. Click the Analyze Loudness tab.

3. Gather the attributes of each file:

-- In Audition 1.x: Click Scan for Statistical Information.

-- In Audition 2.0: Click Analyze Statistical Information.

Note: For detailed information on each of the data fields, click Help.

4. Click the Normalize Tab and then select one of the following options:

-- Normalize To Average Level Of Source Files: This option is preferable if you have a group of files with scattered levels and you want to standardize them. This option generates an average loudness suitable for most delivery methods.

-- Normalize to a Level of: Select this option and enter a value to normalize all files to a specific level you enter in decibels, regardless of the collective average. Note the information field indicating whether or not normalizing to a specific decibel value will cause clipping. If you want to prevent digital clipping while you maintain high decibel levels, implement the Hard Limiter (selected by default). If you're familiar with setting the Hard Limiter, you can also alter the Look-Ahead and Release times.

Note: Most CDs have a maximum RMS between -12 and -5, depending on the style of music. Some are higher, but -10 to -8 is the recommend range.

5. Click Run Normalize.

6. Save your changes.