Mix

Menu Command: Edit | Mix

This is a special editing command for sounds. The sound in the clipboard (use Edit | Copy) is blended (or layered) with the current sound, such as adding vocals to music. You are prompted for the start Time and the mix Volume. The volume is applied to the clipboard sound. The Invert option inverts the Clipboard audio, which is equivalent to subtracting the audio amplitudes instead of adding them.

To mix:

Copy audio to the clipboard. See Edit | Copy.
Move the start marker to the approximate place where you want to mix the clipboard sound. See Editing Overview.
Choose Mix from the Edit menu or click on the Mix button.
Enter the volume to mix the clipboard (0 dB is full volume).
Preview the mix using the play button and adjust the start time and volume as required. Note that you'll need to press the play button again before the new settings are previewed.
Choose OK.