You can split audio in Premiere Pro by using a Razor Tool (C).
Here’s how to quickly split Audio in Premiere Pro:
- Once you have an audio track click onto a Razor Tool in Premiere Pro’s tools menu next to a timeline, or press the shortcut key C.
- Select a place which you want to Split your audio track and click the left mouse button.
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If you wish to merge two separate audio clips into a single clip then you have to align them one to another, click the right mouse button onto the line separating them and choose Join Through Edits from the menu.
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You can find more information about improving audio quality in Premiere Pro here.