[I dont know]

I recently got new excellent headphones and I had to bend them a bit at the top to reduce the strong force, and after I bent them a bit just like how people do on youtube, they seem to be a lot louder than before. I've marked the place where I bent them a bit, on the picture.

 

[Koei]

The frequency response (or better said the frequency response of the sound reaching your eardrum) of headphones changes with positioning on your head, so there might have been some change. But it shouldn't change the volume. If you broke the cable running inside (seems like there is?) I would expect changes other than volume...