HELP: Loud drumming noise!

[blaast]

Our Golf MY16 Highline (R-line option) has developed a drumming noise that has been getting louder over time.
It is a 'wha wha wha wha' sound (sounds like 'what' without the t), that increases in frequency as speed increases.
It can be heard from 30km/h, is loudest at 60-70km/h, then gets quieter above 70km/h, but is still audible.

I have linked a video and audio file of the sound below.
The audio file is probably the best to hear it.
Video
Audio