How does an AM-modulated signal sound like in a speaker?
Sounds are hard to describe in words, so the best thing to do is simply try it.  You will hear the 5 kHz, but it will sortof "buzz" at 900 Hz.

Even if you don't have equipment that does AM modulation, just create a WAV file with this signal and play it thru the PC speakers.  Hearing it yourself is really the only way to answer this question.