[ADTech]

The batteries in the earphone set will not cause this. Because your earphones are infrared from the transmitter, I would not expect them to directly receive the interference from the power supply unless there is a very odd internal failure. I'm more suspicious that the issue is that your transmitter is picking up the noise, either from the power line or via direct radiation.

Does the same interference occur if the laptop power supply is plugged into a receptacle on a different branch circuit served by, usually in a different room?

Is it sensitive to changes in distance or orientation between the power supply and the transmitter.

Trying to determine if the issue is due to conducted radiation (via the home's wiring) or is radiated directly from the power supply to your transmitter or its wiring.