Using multiple tools to flight simulators adds multiple layers of realism to your Flight Simulator. But if various of them bring voice recordings of pilot / copilot / flight attendant, they will sound different from each software i.e. copilot check-lists of FDC live cockpit and copilot of Radar Contact V4, or the ground crew of AES and the one of the Level-D 767.
With FSVoices, you get various US voices for different roles and all are formatted for the listed add-ons. Once in your aircraft, each people has its own and unique voice, no matter the program it comes from.