As several commentors have mentioned, in ear monitor (IEM) type headphones have pretty good sound isolation properties. It's important to note that active noise cancelling (ANC) headphones increase the total sound pressure on your ear drums, while IEMs decrease it, overall. With ANC headphones, you have the environmental sound pressure added to the cancellation signal (which cancels according to perception, not according to physics) added to the pressure of your music. This tends to make them far more damaging to hearing, long term, than simply listening to music. The real solution, if you want to avoid hearing loss and drown out the environmental noise is to use something like Shure IEMs and a pair of shooting or industrial earmuffs. When I ran a lawn service in high school, I had a set of Shure headphones and equipment earmuffs, which blocked something like 50 dB of environmental noise and let me listen to podcasts at a reasonable volume while running a mower 8 hours a day.
Do you have a reference for ANC headphones being more likely to cause hearing loss compared to regular headphones? I find it hard to believe (but would love to stand corrected).
So, upon further reading, I was less informed on that than I had thought. The best explanation I could find is here[1]. Basically, ANC does reduce sound pressure level when it lines up correctly. If you're listening to the sort of ambient noise that it does well with, it gets the phase offset close enough to right to significantly reduce the mechanical force applied to your ear drums. If, on the other hand, you're in an environment where it does a mediocre job, it will still be producing a cancellation waveform, but it won't actually cancel anything, and that will increase the mechanical force applied to your ear drums. So, in an office environment, you'd expect a reduction from the ambient noise of the HVAC system, but an increase from the random nature of your coworkers' conversations. It's hard to say whether you'd have a net reduction or not, but it's not certain, whereas passive noise isolation is certain.
I thought that physically, it is lower-pressure, since sound is physical, and the inverted sound waves that the ANC generates cancel out those from the noise source. Looking at the diagram on https://en.wikipedia.org/wiki/Active_noise_control , I'm not getting how the amplitude is higher, since the resulting sound is quieter, which I'm translating to lower SPL (lower acoustical pressure).
Thought experiment: suppose you have super-loud bass coming from a single point-source at 30hz. You can feel this in your chest. Now, you put a second point-source 180 degrees out of phase in the same place. What would the pressure on your chest feel like? How is this different from how ANC works?
