Other wireless devices around you could cause static on your Bluetooth headset.
When this happens, the clarity of your audio is reduced. It may sound "digitized."
Wireless devices that use the same frequencies as your headset increase the likelihood of this happening. Examples include AirPort (802.11) connections, cordless phones, and other Bluetooth devices.
Turn off any Bluetooth or AirPort services and devices you're not using, and move your phone or its base away from your computer.