[rtpg]

it's hardware dependent, but I was ruining my hearing until I realized that in fact I don't need to turn up the volume from those notifications. Ears can work much like eyes do in the dark/quiet and adapt.

I wonder what the potential output volume range for unpowered headphones is for the volume set at, say, 40% in windows.

[gdrulia]

Well 40% is enough volume for properly hearing what comes out of the headphones speakers. But I'm talking about using headphones with their own volume adjustment or external speakers. If you try to watch a movie on most laptops using their native speakers, you will definitely not going to hear a dialogue at 40%. You will want to make it play louder, but once you try to adjust it you'll be interrupted by this notification. I understand that people might need to realize that loud volume can damage their hearing, but I'm advocating that arbitrary checking of the system volume is not a proper way to do it.

[lucaspiller]

I have some cheap unpowered Sennheiser headphones, and 20% in Windows is plenty loud enough for gaming. At full volume I can have them sitting on my desk and still hear everything clearly :D

[stikypad]

Percent of volume says nothing about the line level, which is hardware specific. Since audio jacks were invented before we had industry standards bodies, there is no specification that hardware manufacturers have to meet. Many provide around 1Vpp, or -10dbV, at max volume, but it's going to vary from device to device. The impedance of the headphones are going to affect the SPL as well, and none of it is likely calibrated to any high degree of certainty unless you're buying professional equipment.