Originally Posted by
trich
This could also be improperly tensioned spokes on the front wheel. For me, it was more of a feeling or vibration coming up through the bike, but there was definitely a noise associated with it, too.
Improperly tensioned spokes usually make a noise easily recognisable, because it's periodic - at every turn of the wheel. Not saying your case is not possible, just that there's another symptom to it, too.
Besides, in the example I cited, there doesn't need to be any weight on the handlebars and front wheel, the noise will still be produced. So, there are various ways to distinguish "my" case from "yours".