MAZDA 2.0 CD140 GT hollow sound???

[Marko pi]

Hello!
I have A problem with my Mazda 2.0 Diesel 2009! At minimum RPM, the car has a normal sound, but as soon as I slightly increase the RPM, a hollow sound from the air intake can be heard! Here I do an video, when engine is at minimum RPM the flap “body throtle” are almost closed, as soon as I slightly increase the RPM the flap opens fully and loud sound is heard! The sound is quite disturbing. Does anyone know what this sound could be? Thanks

Here is the video:

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