Go to \Steam\steamapps\common\Fallout 4\Data and find Fallout4 - Voices.ba2 . Copy this to your desktop.
If you encounter issues with the voice pack, try: fallout 4 english voice pack link
For users looking to experience with its original English performances while keeping subtitles in their native language, the "English Voice Pack" isn't a single mod but a configuration process or a specialized high-fidelity replacement. Review: The Original English Voice Cast fallout 4 english voice pack link
You can force Steam to download the ~4GB English voice pack directly through its interface: fallout 4 english voice pack link