drumming noise - advice needed on what it might be

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mk3 TT 2017 1.8 manual - 36k miles

Hi, I have a slightly concerning noise issue, I’ll try my best to describe it. It’s a rhythmical drumming or thumping sound, maybe 2 or 3 beats per second, and it speeds up and slows down with the speed of the car, not the engine speed, (if I press the clutch the pace of the drumming stays the same). The sound is vaguely similar to a soft and distant sound of a drum, like the ones people hit at a football game (but quieter than the sound of the engine). It’s loudest at 18mph, and is not present at all below 15 or above 22mph. Doesn’t matter if I’m in 2nd or 3rd gear, the sound is the same.

Has anyone had a similar experience or problem or know what it might be or what it might be worth while checking?

I’ve had the brakes checked and there doesn't seem to be anything stuck in the tyres.