I was answering the same question posted by another member the other as well.
There's a couple of reasons for it.
1)Lightweight construction of the air cleaner assembly itself.
2)Wight on the aircleaner assebly.
3)Off center bolt at the base of the aircleaner assembly fatening it to the left sidemember.
The "drone" intensifies/peaks at roughly 2100rpm, the driving range for a torquey diesel and a nuisense on the highway.There's been an odd instance of more or less a similer complaint from some rather Obsessed SE owners saying their car drones whilst accelerating.
There's acouple of things you can do to improve it. Firstly dismantle the aircleaner assembly at inspect the at the base of the assembly. If bushing is torn (examples with higher mileage or excessive "diesel dressed" engines)replace or loosen the bolt enough that it holds the air cleaner firmly in place. Secondly apply a double sided sticky tape to the out lip (where the top cover seats)of the bottom half of the assembly. Do not overtighten the bolt and neither should you try and remove offset as it can only be achieved by a cut/shut job and will leave marks. Furthermore, try whevener to use OE air filters.
The resonance in the airbox was a rather dated method of audibly detecting "valve overlap" and as the engine design hasn't changed so the feature still persists making it more obvious in the quiet cabin of the Corolla. Another method (unorthodox) of eliminating the noise all together is installing an airbox from an imported varient (2C-E/3C-E CE100s). It requires some fabrication so I have never actually done it for anyone but an example tested on a friends car eliminated noise by upto 70%.