meaning of: going around in my head

[Learning_English]

I've got a tune going around/round in my head and I just can't remember the name of it.

Could you explain the parts in bold?
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Please let me know if I have made any mistakes in any of my sentences.

[Yankee]

Hi LE

Have you ever had the experience where you heard a melody and then, for hours afterward, you couldn't get the tune out of your head? As though the tune were being played over and over again and you kept "hearing it" in your mind? That's what I imagine is happening in your sentence.
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