Hard to quantify. Some specific scenarios: - It won't work in a loud bar - It will almost always work in a car where you're the driver and there's a backseat

Hard to quantify. Some specific scenarios: - It won't work in a loud bar - It will almost always work in a car where you're the driver and there's a backseat conversation or the radio is on. - It's fine with street/sidewalk noise. - Not-terribly-loud coffee shops, stores, etc. are also usually just fine.