He most certainly hears you

After your first moan, you manage to stifle back any other noises struggling to escape your mouth, despite the fact that your mind is going blank and the tingling in your crotch isn't letting up any time soon. Unfortunately, before your phone has even finished vibrating, you hear Alex say "I know you're in here," before throwing back the covers.

Now caught, your empty mind realizes that there's no longer a need to remain quiet. Right before Alex's eyes, you arch your back. "Fuuuck!" you moan, your hands forcing your vibrating phone harder against your crotch, trying to gain as much stimulation as possible. When the phone finally stops ringing, you begin to comprehend your situation. Your eyes focus first on Alex, mouth agape, standing beside your bed. A long moment of silent passes between you as you simply stare at each other.

"Uhh..." Alex starts, "I didn't realize that he was 'entertaining' anyone, sorry." He starts shifting his weight a little nervously before starting to crab-walk sideways towards the exit of the room. You notice that his hands are covering his crotch, and with mild amusement realize that he must have an erection from your short display of pleasure. Hell, you can't blame him: if you had seen and heard a girl do that while you had a dick, it would've been able to cut diamonds.