Beer... that's because when you squint your eyes and tilt your head forward to focus on a speaker or other sound source, it changes the angles of your ears and thus changes the geometry of your ears in relation to the source thereby reducing the capacity to collect and funnel sound waves into you ear canals.

Yeah... sounds like bullshit to me too. But it's pretty good bullshit if I do say so myself. And I am a pretty good judge of bullshit. Some say I am a master of bullshit but I am shy to accept such accolades. I shit you not.