A strange new sound I have never heard before, kind of sounds like an ultra sound. I can tell its the wheel, front passenger side. It just started and seems to be getting louder, or im just paranoid. Strange thing to me is when I give it gas or apply the brakes, it goes away. Only makes the rubbing ultra sound noise when coasting. I have also looked for lodged rocks or sticks, seems ok, any ideas?

Could be exhaust pipe support [cross bar].I had this problem.

check for failed wheel bearings or loose wheel on studs. Check suspension ball joints and steering joints the problem is serious so have the front inspected by a competent mechanic

sounds like a brake pad warning clip is making contact with the rotor applying brakes presses pad and quiets the noise. have pad wear checked by mechanic.

????? waht kind of car? and engine size please

sounds like it may be bad wheel hub bearing. wen going down road with no traffic steer left then right left right and see if noise gets louder and softer wen weight shifts from side to side. if it does u may need to get new hub bearings

check that, and you may have a bad wheel bearing on that side.

First, the shop diagnosis sounds a bit strange, unless you are not understanding what you were told.
I have heard of a radius arm but likely I've called it by a different name (like the proper name for a driveshaft is a propeller shaft, but if you call it that no one will know what you're talking about) The part I fail to understand is that its preventing the wheel from freewheeling? Makes no sense.
I suggest that you either have them put the car in the air and physically show you what they are telling you, or have another shop take a look at it and see what they find.
Most front end shimmy I've seen is usually caused by bad ball joints or a bad bushing elsewhere in the suspension.

It usually doesn't pay off to try to play wiser than you are for a professional. Use a close-by garage which can't really lose a customer and let them fix it.

'A strange sound' can be anything from clanking to whaling and the causes are different. If you hit the curb, your camber is probably gone and the rim is damaged. You might have damaged the wheel suspension. In any case it's not smart to drive with it without fixing.

if the noise only happens when the vehicle is in motion...check the front suspension. place the jack under lower control arm ,then get a bar and lift up on the tire..ball joint issues are well known in blazers and cause this condition. if it does the rattle noise when its idling and to op temp--could be the cat converter causing the noise on pass side directly under passenger seat. when cold, smack the cat with rubber mallet and if any rattle is present, cat should be replaced so it dont cause further damage .hope that was helpful !!

not sure about thenoise but sounds like antifreeze got inot your altinator,had that happen to mew one time just an experienced guesss-z