Can we hear sound in a vacuum, if we stand near a black hole? So we can't hear sound in a vacuum because there's no air to propagate the vibration. But from what I understand, black holes make vibrations in space-time. So much so that scientists can detect black holes by measuring these vibrations using equipment that will actually, physically vibrate because of black holes. Right?
Does that mean that if you stand close enough to a black hole... Not close enough to get sucked and die. Wearing only some space suit to keep you alive. Would you actually hear a sound, coming from the black hole, through the vacuum, vibrating your suit and your ear drums? Or do we need specialized equipment to detect those vibrations that our ears drums do not have?
 A: Gravitational waves are measured by using a laser that is split and reflected off of two perpendicular lines with reflective targets at the ends.  The 2 lasers beams are then recombined to produce an interference pattern.  If everything is stationary, there will be no change to that pattern.  If one leg is moving relative to the other then the pattern will shift.  It is that measurement in that shift that tells us if there is a gravitational wave.  Towards the end of two orbiting massive objects that speed increases and subsequently the frequency of the wave.  You can then use those phase changes to create a sound wave which is known as a chirp.  Individual black holes are not going to have this frequency change in general.  This all works because the speed of light is constant in all frames of reference.
The questions around someone sitting in space and hearing the gravitational wave is not possible.  This is because your entire self is in the system.  As your space suit expand and contract due to the gravitational wave so does everything else inside the suit including the individual and the air.  So there will no imposed compression on the air or space suite relative to anything else that would cause sound.  So, in the end, you do not realize anything is actually happening.
