Bear

If the chain is too tight then adjust it so it isn't. It may or may not be causing your problem but it won't help chain and sprocket wear.

I'd be more inclined to think it's a binding caliper. If you can (get a mate to help)raise the front wheel off the floor and spin it, see if you hear anything then.

If it's warped discs you should feel it pulsing through the lever on hard braking, so I don't think it's that.

Obviously diagnosing a noise I can't hear is difficult, but give it a go. Let us know how you get on!