With Bluetooth headphones you can get cut outs and interference from the following the devices that use a similar frequency (2.4 - 2.48 GHz):
Wireless Keyboards and Mouses
WiFi Routers and boosters
Other Bluetooth devices nearby
As the band is so small, when there are devices nearby it fills up easily and becomes congested. When this happens it starts to affect the Bluetooth causing drop outs and interference.
It is hard to prevent this from happening depending on the environment that you are in but it is best to keep a 1 meter away from them if possible