Noise from a Chimney

It would need investigation, but a bass noise from the chimney Is almost certainly from a draft coming down.. I can completely soundproof almost any house depending on how far you would want to go with it.. but noise from a chimney should be an easy fix

A chimney balloon would stop howling noises. From chimney.

I would go for the cheapest option first and what I would do is start from the top and if you are not using your chimney it can be capped to stop the down draught, your local chimney sweep will do that for you , you could also block off the throat of the chimney also , also any other chimneys not in use I would cap off or put on chimney cowlings

As other comments, investigation is needed. The noise is unlikely to be from a neighbour if your house is detached as you imply. It is possible that a draught is causing something inside the chimney to vibrate, hence the hum. If the chimney is being used, I would sweep it thoroughly and see if this helps. If not, try fitting a cowl to the chimney pot or changing an existing cowl to reduce the airflow in the flue. It would also be worth checking and sweeping any flue that joins the main flue if you have more than one fireplace in the property. If the problem persists, try restricting the airflow at the bottom of the flue in the throat of the chimney whilst still retaining enough draw. Good luck. Tom