I don't know why I decide to re-read but I did... and gosh, I misunderstood what you are trying to ask for. My bad. It is clearly that today is just not my day (I misread three times today)...
Sorry about my earlier post which didn't answer your specific question. I'm afraid that I don't understand your question. You mind if I ask you to rephrase your question?
I mean, I did not catch what are you trying to ask: 'how can you make the vibrations for them to hear?"
Do you mean how can I make women orgasm or moaning for them to hear? Ok, it is offical that I am deadbeat tired.
Also about your another question, "what kind of vibrations can you hear?"
I am not sure with myself about that question but I usually feel whenever the vibration comes up. I am very sensitive to vibrations so I can literally feel anything whenever vibration sweeps up and down or left and right or opposite.
Did I get your question right this time...? Ok, time for me to hit the sack.