I'd work to eliminate other easy to check possibilities, then check the bearings directly.
Check there isn't anything between the front wheel and it's mudguard.
Check your chain is well adjusted and lubed. Check no tight spots.
Check type pressures and visual inspection of tyre condition. Sometimes tires can go bad and make silly noises.
Check brake caliper condition, check for binding, clean calipers if necessary.
Check there isn't a pheasant under you seat.
Other things I haven't thought of.
If you don't find anything elsewhere, then I'd look at the bearings next. Get the bike up on it's centre stand and check the front wheel for play in any direction. Check the forks (head stock bearings) too whilst you're at it. Any play change bearings.
Even if there's no play, it can still be the bearings, as sometimes when they're just starting to go bad you just get the noise without any play (yet).
You can take the wheel off and check how the bearings feel with your finger. If notchy or otherwise not free and smooth running replace.
On mine replacing the bearings fixed the silly warble noise.
Possible could be something else, just process of elimination is the best way I can advise.
HTH, Andy