No American state forbids headphones behind the wheel outright. That surprises people, and it is the beginning rather than the end of the answer, because what the rules do instead is vary by state, by how many ears are covered, and by whether an officer decides the way you were using them made you a hazard.
At one end sit states with nothing on the books about it at all. Arizona, Texas and Alabama impose no restriction, even on headphones covering both ears.
That is not the same as being in the clear. Distracted driving statutes still apply, and in places such as Nevada and Michigan, headphone use that happens to coincide with handling your phone can land you on the wrong side of them regardless of what the headphone rules say.
A second group draws the line at two ears. Louisiana, California, Maryland and Washington prohibit wearing them over or in both, while permitting a single earbud.
Others are narrower still. Colorado and Georgia allow one earbud only when the driver is on a call. Alaska carves out an exception for navigation.
With that many variations, the only reliable approach is to read your own state's statutes — both the headphone provisions and the distracted driving ones, since the second can catch you where the first does not.
The legal question and the sensible question are separate, though, and the second has a clearer answer. Driving depends on knowing what is around you, and not all of that arrives through the windscreen. Sirens, a car approaching outside your mirrors, someone leaning on a horn — headphones degrade every one of those, and covering both ears degrades them badly.
There is also a consequence that outlasts any ticket. Even where the practice is legal, an officer can classify it as distracted or reckless driving if it demonstrably affected how you drove. And if you are involved in a collision while wearing them, you are exposed in civil terms whether or not the crash was your doing. Wearing headphones can be argued as negligence in its own right. In states operating comparative or contributory negligence rules, that argument can cut what you recover — in some cases to nothing.
None of which is much of a trade, given how little is gained. Nearly every car built in the last decade offers Bluetooth, an auxiliary input or a USB port. If yours has none of them, an inexpensive FM transmitter will push audio from your phone through the car's own speakers, which is where it belonged in the first place.
