Air purifier making buzzing noise?

Hi, I just bought a holmes HEPA air purifier (literally just bought), and within a few hour it started to make a strange electrical buzzing noise. I believe that it is coming from the ionizer, since when the ionizer is off it does not make this noise.

Is this normal, or is this a problem with the machine? Has anyone else had this problem?

Thanks in advance.
Never mind, I’m getting rid of the thing anyway.